Fact-checked by Grok 2 weeks ago

Siphon

A siphon is a tube or pipe, typically bent into an inverted U-shape, that enables the transfer of a liquid from a reservoir at a higher elevation to another at a lower elevation, allowing the fluid to rise above the level of the source against gravity before descending, without requiring mechanical pumping.^[1]^[2] The operation relies on the difference in hydrostatic pressure between the inlet and outlet ends, where atmospheric pressure pushes the liquid up the rising leg while gravity pulls it down the longer descending leg.^[3]^[1] The physical principle underlying a siphon is described by Bernoulli's equation, which relates pressure, velocity, and elevation in a flowing fluid, showing that the reduced pressure at the siphon's summit—below atmospheric levels—facilitates the upward flow until the liquid crests and accelerates downward.^[1]^[3] This effect is limited by the liquid's vapor pressure and cohesion, preventing operation if the height exceeds about 10 meters for water at sea level due to cavitation risks.^[1] Siphons have been employed since antiquity, with depictions in ancient Egyptian tomb art from before 1100 BCE illustrating their use for drawing water and wine from vessels.^[4] In Hellenistic and Roman engineering, inverted siphons—using pressure-resistant pipes—were integral to aqueduct systems, such as the Aqueduto das Águas Livres in Portugal (18th century, but based on Roman designs) and earlier Roman examples like the Aqua Marcia (144–140 BCE), to navigate valleys while maintaining water flow.^[5] In contemporary applications, siphons are ubiquitous in everyday and industrial contexts: in plumbing for toilet siphon jets that create a vacuum to flush waste efficiently; in aquariums and pools for gravity-fed water changes; in laboratories for safe liquid transfer without spills; and in civil engineering for irrigation channels, spillway discharges in dams, and flood control systems where large-scale siphons move water over barriers.^[3]^[6]^[7] Specialized variants, like self-starting or bell siphons, automate flow in aquaponics and wastewater treatment by trapping air to initiate and break the siphon cycle.^[8] Beyond fluid dynamics, the term "siphon" denotes biological structures in aquatic organisms, such as the paired incurrent and excurrent siphons in bivalve mollusks (e.g., clams) for filter-feeding and respiration, or elongated siphons in burrowing gastropods and cephalopods for drawing in water over distances.^[9] In insects like mosquito larvae, siphons serve as breathing tubes extending to the water surface.^[10] These adaptations highlight convergent evolution in fluid transport mechanisms across taxa.^[9]

Fundamentals

Definition and Basic Operation

A siphon is a tube or conduit designed to transfer liquid from a reservoir at a higher elevation to one at a lower elevation, passing over an intermediate rise, by relying on gravity and atmospheric pressure rather than mechanical pumping. This passive mechanism exploits the natural tendency of fluids to flow downward while enabling the liquid to ascend temporarily against gravity on the inlet side. Siphons are widely used in simple fluid transfer scenarios due to their reliability and lack of moving parts. The basic operation of a siphon begins with priming, where the tube is completely filled with the liquid to eliminate air pockets and form a continuous liquid column. Once primed, the setup creates a pressure differential: the atmospheric pressure acting on the exposed surface of the higher reservoir pushes the liquid up the inlet leg of the tube, while the weight of the liquid column in the descending outlet leg pulls it downward, sustaining flow as long as the outlet remains below the inlet liquid level. This process continues until the source reservoir is depleted or the siphon is interrupted, such as by introducing air into the tube. Siphons have been employed since early times as straightforward devices for gravitational water transfer.^[11] A typical basic siphon features an inverted U-shaped or J-shaped tube configuration, with the inlet submerged in the source liquid, the summit positioned above the liquid surface to form the rise, and the outlet extending to a lower point for discharge. Flexible tubing, often made from rubber or plastic for ease of handling and priming, or rigid pipes like PVC for more permanent installations, are common materials in these simple setups, chosen for their compatibility with the liquid and resistance to corrosion.^[12]

Components and Setup

A siphon is constructed using a simple tube arranged in an inverted U-shape, comprising key components that facilitate liquid transfer. The inlet is the submerged end placed in the source liquid reservoir, allowing liquid to enter the system. The tube itself, preferably of uniform diameter to minimize flow restrictions and ensure even velocity, connects the inlet to the outlet and includes the summit as its highest point, which must rise above the source liquid level. The outlet is the discharge end positioned to release liquid into a lower receptacle.^[13] Proper setup requires positioning the outlet below the surface level of the liquid in the source container to enable gravity-driven flow once initiated. The overall tube length is constrained by atmospheric pressure, which supports the liquid column in the summit; for water at standard conditions, this limits the maximum effective height to approximately 10 meters to prevent the column from breaking due to vapor pressure. Assembly involves securing the tube to avoid kinks or leaks, often using flexible materials like rubber or plastic tubing for ease of handling in practical applications.^[13] To initiate flow, the tube must be primed by filling it completely with liquid to expel air and establish a continuous column. Common priming techniques include applying suction at the outlet end via mouth or a pump until liquid emerges, fully submerging the tube in the source liquid and then lifting the outlet while pinching to retain the fill, or pouring liquid directly into the tube through a temporary opening before sealing and placing the ends. In laboratory settings, such as fluid dynamics demonstrations, priming can involve filling the tube under a tap and using clamps to control the start of flow.^[14]^[13] Air locks, where trapped air pockets disrupt the liquid column and halt flow, represent a frequent setup challenge, particularly if the tube is not fully primed or if connections are loose. These issues are mitigated by selecting non-porous, airtight materials like smooth plastic or glass tubing that prevent air infiltration, ensuring all joints are tightly sealed with clamps or fittings, and verifying complete filling during priming. Avoiding materials with microscopic pores, such as certain fabrics or degraded rubber, further reduces the risk of gradual air entry.^[13] An ideal configuration features a smooth, uninterrupted inverted U-tube with the summit elevated just above the source level and the outlet sufficiently lower to maintain momentum, as depicted in standard engineering diagrams showing symmetric legs for balanced pressure. In contrast, suboptimal setups—such as those with sharp bends at the summit, uneven leg lengths, or the outlet not low enough—can cause intermittent flow or failure to prime, often illustrated in troubleshooting schematics where air bubbles are shown accumulating at high points.^[13]

Historical Development

Ancient and Classical Uses

The earliest documented uses of siphons date back to ancient Egypt around 1500 BCE, where reliefs depict them being employed to extract liquids from large storage jars, particularly in winemaking to separate wine from sediment without contamination.^[15] This technique was crucial in viticulture, as it preserved the quality and purity of the wine by avoiding the mixing of dregs, reflecting the cultural importance of wine in Egyptian society for religious rituals, offerings, and elite consumption.^[16] In Mesopotamia, siphons were similarly applied around 2000 BCE for rudimentary irrigation, siphoning water from the Tigris and Euphrates rivers into fields via small canals to support agriculture in the arid Fertile Crescent.^[17] During the classical Greek period, the engineer Hero of Alexandria advanced siphon applications in the 1st century CE, as detailed in his treatise Pneumatica. Hero described various siphon designs, including the bent siphon for basic fluid transfer, the concentric siphon for controlled flow, the uniform discharge siphon to maintain consistent rates, and adjustable siphons capable of varying output quantities.^[18] These innovations powered elaborate fountains and automata, such as self-operating devices that used siphon networks to create intermittent water displays or mechanical figures, demonstrating pneumatics and hydrostatics for entertainment and engineering demonstration.^[19] The Romans adapted and scaled siphon technology for large-scale water management in aqueducts and drainage systems during the 1st century CE and beyond. Inverted siphons—U-shaped pipes that dipped below ground to cross valleys under pressure—were integrated into aqueduct networks to maintain flow where elevated channels were impractical, with lead or terracotta pipes capable of withstanding hydraulic forces.^[5] A prominent example is the Gier aqueduct serving Lyon, France, which featured multiple parallel siphons, including the Saint-Genis siphon spanning 2.6 kilometers with a 123-meter drop, highlighting Roman engineering prowess in urban water supply and flood control.^[20] In the medieval period, siphon technology was further developed in Islamic engineering. The Banu Musa brothers in 9th-century Baghdad described self-filling and trick siphons in their Book of Ingenious Devices, applying principles of pneumatics for automated water systems and fountains, influencing later European hydraulics.^[21]

Evolution in Modern Engineering

During the 18th and 19th centuries, siphons saw significant integration into emerging industrial hydraulic systems, particularly for water management in mining operations. Inverted siphons, which allow fluid to flow under pressure across valleys or obstacles, were employed to transport water for hydraulic mining techniques, such as the Virginia and Gold Hill Water Company’s system at Nevada's Comstock Lode in the 1870s, where heavy-gauge pipes withstood high pressures to deliver water without pumps.^[22] In Australian gold mining contexts, siphons were routinely used as piping to convey water over barriers, enabling efficient ore processing and reflecting the era's innovative application of fluid dynamics in resource extraction.^[23] These advancements complemented steam-powered systems, including beam engines like the Cornish type, which were primarily used for pumping water from deep mine shafts in operations such as those in Cornwall's tin mines.^[24] In the 20th century, siphon technology underwent standardization, particularly in large-scale infrastructure like dam spillways designed to manage floodwaters. Post-1900, engineers like John S. Eastwood pioneered siphon spillways in American dams, such as the experimental Big Meadows Dam in California around 1907–1913, where the design automatically initiated flow when reservoir levels rose, providing a controlled discharge mechanism without mechanical gates.^[25] This innovation spread to major projects, including siphon spillways at the Bear Valley Dam in California (completed 1913), which featured self-sustaining flow after priming and air vents for regulation, influencing global dam engineering practices.^[26] By mid-century, siphon spillways were codified in plumbing and hydraulic standards, such as those from the U.S. Bureau of Reclamation, ensuring reliable integration into waterworks and irrigation systems for flood control and water level regulation.^[27] Key milestones in siphon evolution included the development of self-priming variants in the early 1900s, driven by automotive needs. Vacuum tank fuel systems, introduced in the 1920s for vehicles like the Plymouth, used engine-driven vacuum to prime siphon action, drawing fuel from the tank to a reservoir above the carburetor and enabling reliable delivery without gravity feed limitations in higher-mounted tanks.^[28] This addressed priming challenges in internal combustion engines, marking a shift toward automated fluid transfer in transportation.^[28] The late 20th century brought a transition to synthetic materials, enhancing siphon durability and cost-effectiveness in plumbing and industrial applications. Polyvinyl chloride (PVC) pipes, first commercially produced for water conveyance in 1935, gained widespread adoption in siphon systems by the 1950s and 1960s, replacing metal conduits due to their corrosion resistance and lightweight properties, as standardized in residential and municipal plumbing codes.^[29] By the 1980s, PVC's formulation improvements allowed for seamless integration into siphon traps and drainage lines, reducing maintenance needs and enabling scalable use in modern infrastructure like sewer laterals and irrigation.^[30]

Theoretical Foundations

Explanation via Bernoulli's Equation

Bernoulli's principle provides the theoretical foundation for understanding siphon flow through the conservation of mechanical energy along a fluid streamline. The principle is mathematically expressed by Bernoulli's equation, which states that for an inviscid, incompressible fluid under steady flow conditions, the total energy per unit volume remains constant:

P + \rho g h + \frac{1}{2} \rho v^2 = \constant

Here, P represents the static pressure, \rho the fluid density, g the acceleration due to gravity, h the elevation head above a reference datum, and v the flow velocity.^[31]^[3] In a typical siphon setup, where a tube connects a fluid reservoir at higher elevation to an outlet at lower elevation and arches over a barrier, Bernoulli's equation is applied along the streamline from the reservoir surface (point 1) through the summit of the arch (point 3) to the outlet (point 2). At point 1, the pressure is atmospheric (P_1 = P_\atm), velocity is negligible (v_1 \approx 0), and elevation is h_1. At point 2, the pressure is also atmospheric (P_2 = P_\atm) with elevation h_2 < h_1 and velocity v_2. Applying the equation between points 1 and 2 yields:

P_\atm + \rho g h_1 + \frac{1}{2} \rho (0)^2 = P_\atm + \rho g h_2 + \frac{1}{2} \rho v_2^2

Simplifying, the height difference \rho g (h_1 - h_2) drives the flow, converting potential energy into kinetic energy at the outlet. This establishes the overall energy balance that sustains the siphon.^[32]^[33] To explain the flow through the uphill section to the summit (point 3, where h_3 > h_1), apply Bernoulli's equation between points 1 and 3, assuming constant tube cross-section so v_3 \approx v_2:

P_\atm + \rho g h_1 = P_3 + \rho g h_3 + \frac{1}{2} \rho v_3^2

Rearranging gives the pressure at the summit:

P_3 = P_\atm + \rho g (h_1 - h_3) - \frac{1}{2} \rho v_2^2

Since h_3 > h_1, the term \rho g (h_1 - h_3) is negative, causing P_3 to drop below atmospheric pressure. This reduced pressure at the summit facilitates the upward flow against gravity in the initial leg of the siphon, as the pressure gradient provides the force to elevate the fluid. The subsequent downhill section then accelerates the fluid, recovering momentum from the gravitational potential and maintaining the overall flow driven by the net elevation drop from inlet to outlet.^[32]^[33]^[34] This derivation relies on key assumptions: the fluid is incompressible (constant \rho), the flow is steady (no time variation), and inviscid (neglecting viscous effects and friction losses along the tube walls). These idealizations simplify the energy conservation to the form above, focusing on pressure, gravitational potential, and kinetic contributions. In practice, friction introduces head losses, reducing actual flow rates compared to the ideal prediction, though the core mechanism remains valid for low-viscosity fluids like water.^[31]^[34]

Flow Velocity and Maximum Height

The flow velocity at the outlet of a siphon, under ideal conditions neglecting friction and viscosity, is given by v = \sqrt{2gh}, where g is the acceleration due to gravity and h is the vertical distance from the liquid surface in the source reservoir to the siphon outlet. This expression, adapted from Torricelli's theorem for efflux from a tank, applies to siphons because the outlet behaves similarly to a small orifice at effective height h, converting potential energy difference into kinetic energy.^[35] In real siphons, actual velocity is lower due to energy losses from pipe diameter, fluid viscosity, and wall friction. For laminar flows (low Reynolds number), the Hagen-Poiseuille equation governs viscous effects, showing volume flow rate Q = \frac{\pi r^4 \Delta P}{8 \mu L}, where r is pipe radius, \Delta P is pressure difference, \mu is dynamic viscosity, and L is pipe length; thus, velocity scales with r^2 and inversely with viscosity./12%3A_Fluid_Dynamics_and_Its_Biological_and_Medical_Applications/12.04%3A_Viscosity_and_Laminar_Flow_Poiseuilles_Law) Friction losses along the pipe, dominant in turbulent flows, are quantified by the Darcy-Weisbach equation h_f = f \frac{L}{D} \frac{v^2}{2g}, where f is the dimensionless friction factor (dependent on pipe roughness and Reynolds number), D is diameter, and h_f is head loss; this reduces effective h and thus velocity.^[36] The maximum elevation of the siphon crest above the source liquid surface is constrained by atmospheric pressure supporting the liquid column, yielding h_{\max} = \frac{P_{\text{atm}}}{\rho g} \approx 10.3 m for water (\rho = 1000 kg/m³) at sea level and standard conditions.^[37] Beyond this height, the pressure at the crest drops below vapor pressure, causing cavitation and flow interruption. As an illustrative example, consider a siphon transferring water with a 5 m vertical drop from inlet surface to outlet and a tube of 1 cm (0.01 m) inner diameter. The ideal outlet velocity is v = \sqrt{2 \times 9.81 \times 5} \approx 9.90 m/s, and the volumetric flow rate is Q = \pi (0.005)^2 v \approx 7.77 \times 10^{-4} m³/s or 0.78 L/s, assuming uniform velocity across the cross-section and no losses. In practice, friction and viscosity would reduce this rate by 10–30% depending on tube length and material.^[35]

Behavior in Vacuum Conditions

Siphons can operate in partial vacuum conditions provided the pressure at the summit does not drop below the vapor pressure of the liquid, which would lead to cavitation and boiling. For water at standard temperatures, the vapor pressure is approximately 2.3 kPa (0.023 atm) at 20°C, imposing a strict limit on the feasible height even in reduced-pressure environments; exceeding this threshold causes the liquid to vaporize, interrupting flow. In full vacuum scenarios, where external atmospheric pressure is absent, siphon functionality relies on pre-priming the tube and using liquids with sufficiently low vapor pressures to maintain tensile strength without cavitation, though practical limits for water remain around 10 meters due to inherent boiling tendencies under low pressure.^[38] High-altitude environments, characterized by diminished atmospheric pressure, proportionally reduce the maximum siphon height to avoid reaching the cavitation threshold. At sea level, atmospheric pressure supports a theoretical maximum of about 10.3 meters for water, but at 5,000 meters elevation, where pressure falls to roughly 54 kPa (half of sea-level value), the effective height limit halves to approximately 5 meters, as the pressure differential driving the flow diminishes. This scaling follows the relation where the maximum height h_{\max} = \frac{P_{\text{atm}} - P_{\text{vapor}}}{\rho g}, with \rho as liquid density and g as gravitational acceleration, highlighting the direct dependence on ambient pressure for preventing vaporization at the summit.^[38]^[39] Experimental demonstrations in vacuum chambers have confirmed these limits, showing flow cessation precisely when summit pressure equals vapor pressure. Historical tests, including those using inverted U-tubes in controlled low-pressure setups, illustrate that water siphons fail beyond the vapor pressure threshold, with bubbles forming and halting transfer, while low-vapor-pressure fluids like ionic liquids enable sustained operation in near-vacuum at heights exceeding standard limits. Such evidence underscores implications for low-pressure applications, such as space-based fluid management, where adjusted siphon designs incorporating the pressure-vapor equation mitigate cavitation risks in extraterrestrial or high-vacuum contexts.^[38]^[40]

Practical Aspects

Functional Requirements

For a siphon to function reliably, the fluid must exhibit specific properties that support continuous flow driven by gravity and hydrostatic pressure differences. The fluid should be wetting relative to the tube material, characterized by a contact angle less than 90°, which allows the liquid to spread and adhere to the surface, preventing gaps or air pockets in the liquid column.^[41] For instance, water on clean glass has a contact angle near 0°, enabling effective wetting and siphon operation, while mercury on glass has a contact angle exceeding 140°, resulting in poor adhesion and unreliable flow due to non-wetting behavior.^[42] Additionally, the fluid must be incompressible, as siphons depend on the near-constant density of liquids to maintain pressure gradients without significant volume changes under flow conditions.^[1] The operating pressure along the siphon, particularly at the summit, must exceed the fluid's vapor pressure to avoid cavitation, where vapor bubbles form and collapse, disrupting the flow and potentially stopping the siphon entirely.^[43] Environmental conditions play a critical role in siphon performance by influencing fluid dynamics. Temperature affects viscosity, with liquids like water experiencing reduced viscosity as temperature rises, which lowers flow resistance and can increase the siphon rate up to a point limited by other factors.^[44] Higher temperatures also elevate vapor pressure, narrowing the margin against cavitation and potentially reducing the maximum allowable siphon height.^[38] The inclination angle of the siphon legs impacts flow efficiency; steeper angles generally increase the flow rate by reducing the tube length and frictional losses.^[45] Material and design specifications are essential for minimizing losses and ensuring airtight operation. Tubes should feature smooth interiors to reduce frictional drag, as rough surfaces increase energy dissipation and slow flow according to the Darcy-Weisbach equation principles.^[46] A uniform cross-section throughout the tube prevents velocity variations that could induce turbulence or separation, promoting steady laminar or transitional flow..pdf) Joints and connections require robust seals to block air ingress, as even minor leaks can introduce bubbles that break the siphon by interrupting the continuous liquid column.^[47] Troubleshooting flow interruptions focuses on identifying and addressing common failure modes. Breaks in flow often stem from leaks allowing air entry or blockages restricting passage, detectable by abrupt cessation of discharge or gurgling sounds indicating partial priming loss.^[48] To resolve, inspect all connections for seal integrity and test under low flow to pinpoint ingress points, then repair with appropriate gaskets; for blockages, disassemble and flush the tube to clear debris without introducing additional air.^[47]

Automatic and Intermittent Variants

Automatic siphons incorporate designs that enable self-initiation and sustained flow cycles without ongoing manual intervention, relying on hydraulic principles to prime and regulate operation. Bell siphons, a common automatic variant, consist of a reservoir, a cylindrical bell positioned over a vertical riser pipe, and an air vent or tube integrated into the system. As water accumulates in the reservoir from a continuous inflow, the rising level eventually submerges and seals the top of the riser, creating a partial vacuum that initiates the siphon effect and rapidly drains the reservoir.^[8]^[49] Once the water level drops sufficiently, air enters through the vent tube or hole, breaking the vacuum and halting the flow, allowing the reservoir to refill for the next cycle.^[8] This process can reference basic priming by initially filling the reservoir to establish the seal, but operates autonomously thereafter.^[49] Air-break designs function similarly but emphasize controlled air ingress to initiate or terminate flow, often using a dedicated vent pipe positioned at a critical elevation within the siphon leg. In these systems, inflow fills the upstream chamber until it overflows into the siphon inlet, displacing air and starting the draw; the air-break pipe then admits atmospheric pressure to disrupt the siphon when the downstream level equalizes appropriately.^[50] Such mechanisms ensure reliable automation without mechanical components, making them suitable for applications requiring periodic drainage. Intermittent variants, such as dosing siphons or adapted bell configurations, achieve cyclic operation by accumulating inflow until a threshold triggers discharge, followed by a reset phase. Dosing siphons, for instance, feature a bell-like chamber or inverted U-shaped trap that fills gradually with irregular inflows, building head until overflow initiates the siphon, delivering a calibrated volume in a surge before air entry via an internal vent resets the system.^[50]^[51] Trapezoidal or bucket-style siphons operate on a fill-overflow-reset principle, where the chamber adopts a trapezoidal cross-section for stable head buildup or incorporates a bucket-like trap that tips or vents upon filling, commonly employed in aquarium flood-and-drain setups or controlled dosing scenarios.^[50] In these, floats may supplement vents to fine-tune reset timing, though many rely solely on hydraulic balance. For example, a bell siphon in a small aquarium system with a 10 L reservoir can cycle every 5 minutes, with fill phases lasting longer than rapid drains to optimize oxygenation and nutrient delivery.^[49]^[52] These variants offer key advantages, including energy-free repetition for precise dosing or draining tasks, minimal maintenance due to the absence of moving parts, and consistent performance over extended periods, as demonstrated in systems operational for over a century in dosing applications.^[50]^[51]

Engineering Applications

Drainage and Spillway Systems

Siphon spillways serve as critical components in dam infrastructure for managing reservoir overflow and flood prevention, particularly where space constraints limit traditional overflow designs. These structures utilize siphonic action to automatically discharge excess water once the reservoir level rises sufficiently to prime the system, eliminating the need for mechanical gates and enabling rapid response to rising waters. A prominent example is the auxiliary spillway at McKay Dam in Oregon, an embankment structure operated by the U.S. Bureau of Reclamation, where the siphon activates to route surplus flow downstream during high-water events.^[53] Another instance is the service spillway at Salmon Lake Dam, also under Reclamation management, demonstrating the reliability of siphon spillways in maintaining stable water levels in compact settings.^[53] The design of siphon spillways typically incorporates a hooded or saddle configuration to facilitate self-priming, where the inlet submerges as the water level approaches the crest, drawing air out and initiating full siphonic flow. This automatic priming ensures efficient discharge without external intervention, though the systems are best suited for moderate capacities due to limitations in scaling for extreme floods. In practice, the siphon pipe is integrated into the dam body or abutment, with the outlet directed to energy-dissipating features to protect downstream channels.^[54] In drainage applications, inverted siphons provide an effective means to transport water across depressions, tunnels, or slopes in large-scale water management systems, functioning under pressure to navigate below hydraulic grade lines. These setups are commonly integrated into urban stormwater networks to bypass obstacles like roadways, utilities, or natural valleys, ensuring continuous flow without surface disruption. For example, guidelines from the Texas Department of Transportation outline inverted siphons for conveying stormwater under existing infrastructure such as sanitary sewers or water mains, with multiple barrels often used to handle peak flows and prevent sedimentation.^[55] The U.S. Federal Highway Administration's Urban Drainage Design Manual further emphasizes their role in transportation-related stormwater systems, where they cross under highways or rail lines while maintaining velocities above 0.9 m/s to suspend solids.^[56] Capacity calculations for both siphon spillways and inverted drainage systems focus on scaling for high-volume flows, accounting for factors such as pipe diameter, elevation differences, and frictional losses to achieve design discharges. Engineers compute the minimum of inlet and outlet capacities, incorporating head losses from bends, inlets, outlets, and pipe friction using equations like the Darcy-Weisbach formula, ensuring the system handles peak events without cavitation. Pipe lengths in these installations commonly reach up to 100 meters, as seen in urban designs spanning 80 to 120 meters across obstacles, though longer configurations up to 400 meters are feasible with multi-barrel arrangements for enhanced throughput.^[57]^[58] Case studies from the 2020s highlight advancements in understanding siphon break phenomena for improving pipeline integrity in drainage and spillway contexts. A 2022 study published in the Journal of Fluids Engineering examined how leaks near the apex of an inverted siphon trigger air entrainment and flow interruption, revealing that leakage above the hydraulic grade line proximate to the top inverted U-section causes rapid siphon breakage, which can be monitored for early leak detection in water conveyance pipelines. This research, conducted through computational fluid dynamics simulations, underscores the potential for pressure transient analysis to identify and locate faults in operational siphon systems, enhancing maintenance strategies in flood-prone infrastructure. Recent projects as of 2025 include replacing gates with siphon pipes at Grant Lake Reservoir in California for improved spillway management, and full replacement of the St. Mary Canal siphon in Montana to enhance irrigation reliability.^[47]^[59]^[60]

Measurement and Sanitation Devices

Siphon rain gauges employ a tipping bucket mechanism to measure precipitation accurately. Rainfall collects in a funnel and flows through a siphon that regulates the rate to the bucket, ensuring consistent measurement regardless of intensity. Once the bucket accumulates approximately 0.2 mm of water, it tips, emptying via the siphon action and triggering a counter or switch to record the event.^[61]^[62] In sanitation systems, the flush toilet utilizes a siphon jet within the trap to facilitate efficient waste removal. Invented in 1596 by Sir John Harington as an early water closet, the design was modernized in the 19th century with advancements like the S-trap by Alexander Cumming in 1775 and the one-piece unit incorporating siphonic flushing by Thomas Twyford in 1885. The mechanism works by rapidly filling the trap with water from the bowl's base, creating a siphon that draws out contents with minimal backflow. Modern low-flow implementations achieve efficiency with full flush volumes of 4.8 to 6 liters (1.28 to 1.6 gallons), depending on regional standards and dual-flush options, promoting water conservation while maintaining hygiene (as of 2025).^[63]^[64]^[65] Other devices leverage siphon principles for measurement and dispensing. Siphon bottles for carbonated drinks operate under internal pressure to self-dispense liquid through a tube, preserving carbonation until use. In barometry, siphon tube designs maintain mercury levels in the cistern by adjusting the column through atmospheric pressure differences in a U-shaped configuration, enabling precise pressure readings.^[66]^[67]

True vs. Non-True Siphons

A true siphon is characterized by a continuous column of liquid filling the entire tube, allowing gravity to drive the flow from a higher reservoir, over an elevated hump, to a lower reservoir without any external energy input or pressure source. This setup relies on the cohesion and tensile strength of the liquid to maintain the column under negative pressure at the summit, with the descending leg's greater gravitational pull overcoming frictional losses to sustain passive flow. The maximum height of the inlet leg is limited by the liquid's ability to withstand tension without cavitation, typically around 10 meters for water at sea level under standard conditions.^[38] In contrast, non-true siphons, often mislabeled as such, involve mechanical assistance rather than purely gravitational action. For instance, chain pumps employ an endless chain fitted with discs or buckets that lift liquid through mechanical rotation, relying on external power or manual effort for elevation rather than a continuous liquid column.^[68] Similarly, the Archimedes screw functions as a mechanical pump, using a rotating helical blade within a cylinder to displace and elevate fluid via positive displacement, not passive siphon dynamics.^[68] Historical misnomers further blur the distinction, particularly in the 19th century when devices termed "siphon pumps" were common but operated via active suction mechanisms, such as piston-driven lifts, instead of passive gravitational flow.^[69] These suction-based apparatuses, prevalent in mining and water extraction, required manual or engine power to create vacuum and draw liquid, contrasting with the self-sustaining nature of true siphons.^[70] A persistent myth about true siphons is that they "suck" liquid upward against gravity, implying a pulling force from the outlet. In fact, once primed, the flow is initiated and maintained by atmospheric pressure pushing on the free surface of the source liquid, combined with gravity accelerating the column down the longer outlet leg, preventing any true suction beyond priming. This atmospheric role stabilizes the system by countering potential vapor formation but does not drive the motion; experiments in vacuum confirm siphons can operate without air pressure if liquid tension holds, though practical limits apply.

Anti-Siphon and Safety Mechanisms

Back siphonage, also known as backsiphonage, occurs when a sudden drop in water pressure within a plumbing system creates a partial vacuum, reversing the flow and potentially drawing contaminated water from fixtures or equipment back into the potable supply.^[71]^[72] This hazard is particularly relevant in scenarios involving submerged inlets or interruptions in supply pressure, risking the introduction of pathogens or chemicals into drinking water lines.^[71] To mitigate this, air gaps provide a physical separation between the water outlet and the flood rim of a receiving vessel, ensuring no continuous connection that could facilitate reversal; these are effective for both low- and high-hazard applications under siphonage conditions.^[71]^[72] Check valves, which permit flow in one direction only, serve as another primary prevention method by closing automatically upon detecting reverse pressure, commonly installed in irrigation and drainage lines.^[73] Anti-siphon valves, often integrated as vacuum breakers, are essential components in faucets, sprinklers, and irrigation systems to interrupt siphon action by admitting air into the line when downstream pressure falls below atmospheric levels.^[74] These devices typically feature a check valve paired with an air inlet that activates upon a pressure drop of approximately 1-2 psi, breaking the vacuum and preventing contaminant backflow without interrupting normal forward flow.^[75]^[76] In outdoor faucets and sprinkler heads, for instance, the vacuum breaker ensures that stagnant or fertilizer-laden water does not reverse into the main supply during pressure fluctuations.^[77] Regulatory standards from organizations like the American Society of Mechanical Engineers (ASME) and the International Plumbing Code (IPC) mandate anti-siphon protections in potable water systems to safeguard public health, with requirements intensifying after the 1974 Safe Drinking Water Act and subsequent amendments.^[78]^[79] The IPC, under Chapter 6 on water supply and distribution, specifies backflow prevention devices, including vacuum breakers and air gaps, for fixtures like lavatories and hose bibbs to prevent contamination in drinking, bathing, or food-processing applications.^[78] ASME standards, such as A112.18.1 for plumbing fixtures, incorporate anti-siphon features in faucet designs, with widespread adoption following post-1970s federal and local codes that addressed historical backflow incidents.^[80] These regulations apply broadly, including brief protections against siphon effects in toilet flush mechanisms to avoid drawing bowl water back into the supply.^[78] For more robust protection in industrial settings, reduced pressure zone (RPZ) assemblies employ dual check valves separated by a relief valve that vents to the atmosphere if pressure between the checks drops, effectively countering both backsiphonage and backpressure in high-hazard continuous-flow applications like manufacturing processes or fire suppression systems.^[81] Rated for pressures up to 150 psi and temperatures from 33°F to 140°F, RPZ devices are required where severe contamination risks exist, such as in chemical handling facilities.^[82] Trap primers, meanwhile, automatically dispense small amounts of water into floor drains or plumbing traps to replenish seals depleted by evaporation or minor siphonage, preventing sewer gas ingress in large commercial or industrial buildings with infrequent drain use.^[83] These pressure-activated primers, often requiring just a 3-10 psi drop to function within 20-150 psi operating ranges, ensure trap integrity without manual intervention.^[84]^[83]

Specialized Siphon-Like Devices

The siphon coffee maker, also known as a vacuum pot or syphon brewer, is a device that employs vapor pressure and vacuum to brew coffee, diverging from traditional siphon principles by relying on temperature-induced pressure changes rather than solely gravity-driven flow over a barrier.^[85] It consists of two chambers connected by a tube: water in the lower chamber is heated, producing steam that forces it upward into an upper chamber containing ground coffee, where immersion brewing occurs; subsequent cooling condenses the vapor, creating a partial vacuum that draws the brewed coffee back down through a filter into the lower chamber.^[86] This method, patented in variations as early as the 1830s by Loeff of Berlin and popularized in 1840 by Mme. Vassieux's design, yields a clean, full-bodied extraction due to the controlled immersion and filtration process.^[87] An inverted siphon serves as a pressurized conduit in civil engineering, allowing fluid transport beneath obstacles such as rivers, roads, or utilities where gravity flow alone is insufficient, functioning as a full-flowing U-shaped pipe operating under positive pressure below the hydraulic grade line.^[55] Commonly applied in sewer systems to cross barriers, it drops the pipeline to a lower elevation, maintains flow through sealed, pressure-rated materials like reinforced concrete or PVC, and includes access points for maintenance to prevent blockages from solids settling in the sag.^[88] Unlike open-channel siphons, this modified form requires pumping or upstream head to initiate and sustain pressurized operation, ensuring reliable conveyance in urban drainage infrastructure. Ancient siphon-like devices, such as the Pythagorean cup and Heron's siphon, demonstrate early ingenuity in using air traps to regulate fluid levels, often as novelty or educational tools that mimic self-regulation without continuous external input. The Pythagorean cup, attributed to the 6th-century BCE philosopher Pythagoras, features a central hollow stem with a U-shaped siphon tube hidden within; liquid fills normally up to the tube's bend, where an air pocket prevents flow, but overfilling submerges the trap, activating the siphon to drain the entire vessel through the base via gravity and atmospheric pressure.^[90] Similarly, Heron's siphon, a 1st-century CE hydraulic apparatus also called Heron's fountain, uses interconnected vessels and tubes with air displacement to create intermittent upward jets of water that appear self-sustaining, relying on an initial air trap in the lower chamber to build pressure and limit flow to a predetermined level before exhausting the supply.^[91] These devices, while not true siphons in the classical sense due to their reliance on air management for cutoff, illustrate foundational principles of fluid dynamics in antiquity. Venturi siphons adapt the Venturi effect—a pressure drop from fluid acceleration through a nozzle constriction—to initiate suction in low-head applications, commonly in aquariums for debris removal without manual priming. In a typical setup, a submersible pump forces water through a narrowed Venturi tee, generating low pressure at the throat to draw in a secondary flow, such as gravel and waste-laden water from the tank bottom, which then siphons into a collection chamber lined with filter media.^[92] This powered variant, often DIY-constructed with PVC fittings and inline pumps rated around 200 gallons per hour, facilitates efficient cleaning in bare-bottom tanks by automating the initial draw, though it requires electrical safety measures like GFCI outlets to mitigate risks near water.^[92]

Natural Occurrences

Biological Siphons in Anatomy and Species

In biology, a siphon refers to a tubular anatomical structure that facilitates the intake, circulation, or ejection of fluids, often enabling propulsion, feeding, or respiration in aquatic or semi-aquatic organisms. These structures are prevalent in various invertebrate phyla, where they function as muscular conduits that leverage hydrostatic pressure and peristaltic contractions to move water or other fluids unidirectionally. For instance, in cephalopod mollusks such as squid, the siphon serves as a versatile organ for jet propulsion, expelling water forcefully to achieve rapid locomotion. The anatomy of biological siphons typically includes muscular walls composed of circular and longitudinal fibers that contract to generate flow, along with one-way valves that prevent backflow and ensure efficient directionality. In bivalve mollusks like clams and oysters, paired incurrent and excurrent siphons are specialized for filter feeding: the incurrent siphon draws in water containing plankton, while the excurrent siphon expels filtered waste and excess water, with the entire system embedded in the mantle cavity for protection. These siphons can extend via extensible tissues, allowing the organism to remain buried while accessing surface water.^[9] Across species, siphons exhibit diverse adaptations tied to ecological niches. In cephalopods, including octopuses, the siphon not only propels the animal but also ejects ink for defense, with the funnel valve enabling precise control over expulsion direction. Tunicates, or sea squirts, utilize a simple siphon system for passive water circulation: water enters through an oral siphon, passes over a pharynx for filtration and gas exchange, and exits via the atrial siphon, supporting their sessile lifestyle. In insects, siphons refer to respiratory tubes in aquatic larvae, such as the elongated siphon in mosquito larvae (Aedes spp.) that extends to the water surface for breathing, piercing the surface film to access atmospheric oxygen while the body remains submerged.^[93] Evolutionary adaptations in siphon morphology often scale with body size and habitat demands, enhancing efficiency in fluid dynamics. For example, in burrowing bivalves like shipworms (Teredo navalis), siphons are elongated and protected by a calcareous tube, allowing filter feeding in submerged wood while extending to the surface. Such adaptations reflect selective pressures for extended reach in protected or embedded lifestyles.

Geological and Riverine Phenomena

In karst aquifers, geological siphons occur where groundwater flows through solution-enlarged conduits, caves, or fractures, driven by hydraulic gradients that create siphon-like effects due to pressure differences. These systems are prevalent in limestone regions, such as the Edwards Aquifer in Texas, a highly transmissive karst aquifer characterized by rapid conduit flow through faulted and fractured Cretaceous limestones, enabling water to move efficiently over long distances without surface exposure.^[94] In such environments, water enters via sinkholes or losing streams and travels through subterranean channels, emerging at lower elevations where the outlet is below the regional water table, mimicking a siphon by maintaining flow through negative pressure in the conduit summit. A notable case is the Fuentetoba Spring in Spain, an unconfined karst system where siphoning drains three hydraulically connected synclines, producing a mean discharge of 210 L/s influenced by upstream reservoir dynamics and conduit geometry.^[95] Siphon springs represent a specific manifestation of these processes, emerging from hillsides or valley floors due to underground pressure differentials in confined aquifers. In artesian conditions, water rises under hydrostatic pressure from deeper permeable layers overlain by impermeable strata, but in siphon variants, the flow continues beyond the static level through inverted U-shaped conduits, where atmospheric pressure at the outlet pulls the column downward. This results in vigorous discharge even when the spring orifice is elevated above the surrounding base level, as seen in vauclusian springs like those in Albania's karst terrains, where syphon action sustains high-velocity outflows from deep aquifers.^[96] The phenomenon is explained by Bernoulli's principle applied to groundwater, with negative pressures at the conduit crest preventing cavitation unless vapor pressure thresholds are exceeded.^[48] In riverine settings, siphon effects can influence karst rivers where streamflow is captured into underground conduits by in-stream sinkholes, maintaining flow through pressure-driven drainage. These phenomena play significant roles in environmental processes, including erosion and sediment transport, as concentrated siphon flows in karst conduits enlarge fractures and caves, contributing to landscape evolution and potential sinkhole development.^[97] In groundwater modeling, siphon effects are incorporated to simulate intermittent or rhythmic spring discharges, improving predictions of aquifer recharge and vulnerability in heterogeneous karst systems.^[98] Recent 2020s studies highlight their impact on slope stability; for example, research on siphon drainage in slopes with long horizontal pipes demonstrates enhanced capacity to lower pore water pressure, reducing landslide risks in karst terrains by up to 50% under varying heads, as tested in laboratory models.^[99] Such findings underscore siphons' dual role in facilitating drainage while exacerbating erosion if unmanaged, informing sustainable groundwater management in vulnerable regions.^[100]

Modern Research and Innovations

Advances in Siphon Physics

Recent experimental studies have advanced the understanding of internal pressures within siphons by employing direct sensing techniques to measure hydrostatic conditions along the tube. In a 2025 investigation, researchers designed two specialized apparatuses: one for profiling pressure variations across the siphon length and another focused on the summit. These measurements revealed pressure variations consistent with Bernoulli's equation, accounting for viscous and quadratic drag effects, with internal pressures below atmospheric levels but no tension in the liquid column.^[101] This work has contributed to resolving earlier debates on siphon mechanisms. The 2025 study disproves "chain model" interpretations—where liquid behaves like a flexible chain under gravity—using CO₂ siphon experiments, while affirming pressure-driven flow without reliance on simplistic "pull" theories or cohesive tension.^[101] In the realm of thermal siphons, 2025 research has explored the role of on-site potential in regulating heat-driven flows within networked structures. By reconstructing potential landscapes in two-dimensional lattices, scientists demonstrated precise control over thermal currents, enabling rectification and reversal of directed heat transport in symmetric setups. This approach highlights how local potential modifications can harness thermal-siphon effects for efficient energy direction in complex systems.^[102] Advancements in flow modeling have addressed limitations in predicting siphon velocities, particularly for discontinuous regimes. A 2021 theoretical framework introduced novel formulas that integrate both continuous and discontinuous flow states while accounting for air release from entrained bubbles in the liquid. These equations improve accuracy in velocity predictions by incorporating air entrainment dynamics, validated against experimental data, and extend beyond classical Bernoulli applications for more reliable simulations in variable conditions.^[103]

Emerging Applications and Standards

In recent years, siphon-based thermal desalination systems have emerged as a promising innovation for seawater purification, particularly through passive solar-driven evaporation processes. Researchers at the Indian Institute of Science developed a scalable, salt-resistant multistage system in 2025 that utilizes a composite siphon mechanism to supply saline water to evaporators, overcoming limitations of capillary-based designs by preventing salt accumulation and enabling larger-scale operation.^[104] This approach achieves a water production rate of 6.23 liters per square meter per hour under one-sun illumination (1000 W/m²) in a 15-stage configuration, with thermal-to-water collection efficiency reaching approximately 423% through latent heat recycling across stages.^[104] Compared to traditional single-stage solar desalination systems, which typically yield 1-2 liters per square meter per hour, this represents a substantial efficiency enhancement, primarily via the passive siphon flow that maintains a thin air gap for optimized evaporation and condensation.^[104] In urban water infrastructure, research from 2022 has explored siphon breaks as a diagnostic tool for localizing leaks in water mains. Studies have demonstrated that pipe punctures or leaks above the hydraulic grade line, particularly near the inverted U-section of siphon pipes, induce siphon breakage by disrupting flow continuity, allowing pressure and flow anomalies to pinpoint leakage locations with high precision. This phenomenon has been modeled hydrodynamically to differentiate leakage effects from normal siphon operation, aiding non-invasive detection in pressurized urban networks where traditional methods like acoustic sensing may fall short.^[105] Such applications enhance maintenance efficiency in cities facing aging infrastructure, reducing water loss estimated at 20-30% globally in distribution systems. Standardization efforts for siphons have advanced to support reliable integration in modern systems. The ISO 4064 series, updated in 2024, provides specifications for water meters in fully charged closed conduits, ensuring accurate flow measurement in siphon applications by defining performance classes (e.g., R values for flow range) and test protocols for volumes up to 1 MPa pressure. For siphonic roof drainage, the ASPE/ANSI 45-2025 standard, released in May 2025, outlines design criteria for full-bore operation and priming in engineered systems, incorporating post-2020 adaptations for intensified rainfall due to climate change, such as increased capacity factors for extreme events up to 100-year hourly rates.^[106] These updates align with broader ASCE guidelines emphasizing resilient infrastructure, recommending hydrologic models that adjust precipitation volumes by 20-50% to account for climate projections in drainage sizing.^[107] Looking ahead, siphons are being integrated into microfluidics for precise fluid control in lab-on-chip devices. Gravity-driven siphon valves enable sequential, event-triggered fluid release in centrifugal platforms, facilitating multistep assays like immunoassays without external pumps, as demonstrated in 2021 designs achieving controlled flow rates down to microliters per minute.^[108]

References

[1]
52.5: The Siphon - Physics LibreTexts
Aug 7, 2024 · A siphon (or syphon, from the Greek σ ⁢ ι ⁢ φ ⁢ ω ⁢ v ) is a tube that transfers liquid from a reservoir at higher elevation to a reservoir at ...
[2]
Siphon | Harvard Natural Sciences Lecture Demonstrations
A siphon is a device that allows the transfer of a fluid from one reservoir to a second at a lower level even though the first part of the journey is up-hill.
[3]
2.972 How A Toilet Works - MIT
Siphoning is used in transporting a fluid from a reservoir of higher elevation to one of lower elevation. Bernoulli's equation (shown below) can help explain ...
[4]
62. The Invention of the Siphon
1. Egyptians siphoning off water or wine. (From. Manners and Customs of the Ancient Egyptians, by J. G.. Wilkinson (London, 1837).
[5]
Siphons in Roman (and Hellenistic) aqueducts
Commonly the pipes in the bottom of a valley were laid down on a siphon-bridge so that the river in the valley could pass below without damaging the aqueduct.
[6]
Siphon - Fluid Mechanics | Civil Engineering - Study Material
Aug 22, 2024 · A siphon is a long bent pipe which is used to carry water from a reservoir at a higher elevation to another reservoir at a lower elevation ...
[7]
What Is a Toilet Siphon and How Does One Work? - This Old House
Jan 10, 2021 · A siphon is a tube that lets liquid flow upward, above the surface of the origin reservoir, and then downward to a lower level without using a pump.
[8]
Automatic Bell Siphon Explained - Practical Engineering
Mar 6, 2017 · A bell siphon has a reservoir, bell, and riser. Water seals the riser, creating a vacuum, drawing more water. Air enters, breaking the siphon, ...
[9]
Siphon Definition and Examples - Biology Online Dictionary
May 29, 2023 · A device, consisting of a pipe or tube bent so as to form two branches or legs of unequal length, by which a liquid can be transferred to a lower level.
[10]
Comparative anatomy of siphons in tellinoidean clams (Bivalvia ...
Siphons are tubular organs formed by fusion and posterior extension of the marginal mantle folds. They are supposed to have performed key roles in the ...
[11]
[PDF] A Remotely Controlled Siphon System for Dynamic Water Storage ...
Jun 30, 2016 · Siphons have been known since early times as simple and inexpensive devices for transferring water using gravitational force (Potter and Barnes, ...
[12]
What is A Siphon? - Pump & Flow
A siphon is any device (usually an inverted U shaped pipe ) used to convey fluids from a higher elevation to a lower height without the need for pumps.
[13]
Function and use of a Syphon pipe/tube | Mcneil Instruments Inc.
How a Syphon Works · Setup: Place one end of a tube in the source container (higher position) and the other end in the destination container (lower position).
[14]
GFD Lab Demo IV 4ii00 Geostrophic flow, geostrophic adjustment
Start a siphon by filling the tube with fresh water, pinching in firmly near the middle (which will prevent flow everywhere in the tube) and immersing one end ...Missing: methods | Show results with:methods
[15]
Exploring the boundary between a siphon and barometer in ... - Nature
Apr 22, 2014 · The first recorded use of the siphon was in ancient Egypt where the Egyptians used siphons in irrigation and winemaking to separate wine from ...
[16]
Ancient Egyptian Wine: Types, Making It, Vineyards
Ancient Egyptian Wine: Types, Making It, Vineyards. ANCIENT EGYPTIAN WINE ... siphon (see illustration) to keep the wine dregs from mixing with the wine ...
[17]
Agriculture in the Fertile Crescent & Mesopotamia
Mar 22, 2023 · At first, irrigation was conducted by siphoning water directly from the Tigris-Euphrates river system onto the fields using small canals and ...
[18]
THE PNEUMATICS OF HERO OF ALEXANDRIA
1. The bent Siphon · 2. Concentric or inclosed Siphon · 3. Uniform discharge Siphon · 4. Siphon which is capable of discharging a greater or less quantity of ...
[19]
Frolicsome Engines: The Long Prehistory of Artificial Intelligence
May 4, 2016 · The first-century-AD engineer Hero of Alexandria described lots of automata. Many involved elaborate networks of siphons that activated ...
[20]
The Aqueducts and Water Supply of Ancient Rome - PubMed Central
Most Roman aqueducts used springs, often augmented by tunneling to increase groundwater flow, providing abundant water for the city.
[21]
Engineering Marvels on the Comstock Historical Marker
The system required the development of an inverted siphon to carry the water uphill without pumps and a heavy gauge pipe to withstand the pressure. The system ...
[22]
[PDF] An Archaeologist's Guide to Mining Terminology
In the nineteenth century mining engineering was a particularly innovative ... siphon: piping used to convey water over an obstacle or across a ...
[23]
Kew Bridge Cornish Beam Engines - ASME
The Cornish engine was developed to pump water from mines in the early 19th century and some of the finest examples were built for waterworks, like those at ...
[24]
[PDF] ,mBMa;:--C& - Loc - Library of Congress
Eastwood acknowledged the siphon spillway as innovative and unusual for American dams. After the Big Meadows project aborted, he did not use a siphon spillway ...
[25]
[PDF] Gold Creek Dam and its Unusual Waste Waterway (1890-1997)
In this paper, the authors review the historical development of the dam and the waste waterway. The authors will show that the dam and its 1890 spillway were ...
[26]
[PDF] Dams and Public Safety - Bureau of Reclamation
A history of dams is included to emphasize knowledge which had very early origins. Many of the experiences in ancient lands are still relevant today. The most ...
[27]
Vacuum Tank Fuel Pumps (circa 1920s) - Looking for Tech help
Jun 20, 2005 · I have a vacuum tank type fuel fuel pump on my 1929 Plymouth that has worked fine for 30 years and 5000 miles. However, it stopped working recently.
[28]
Major Innovations In Fuel Pump Design Since 1900 | GMB Blog
1900-1920s: Fuel Was Supplied To The Engine Via Gravity · 1920s: The Mechanical Fuel Pump Became Commonly Used In Cars.
[29]
The Early History of PVC Pipe - JM Eagle
PVC was discovered in 1835, first industrial developments in 1912, first tubes in 1932, and first pipes in 1935, used for water supply and waste water.
[30]
The History and Development of PVC Piping - Miller Plastic Products
Nov 8, 2021 · PVC was created in the 19th century, used in Germany for water, moved to the US in the 1930s, and became standard in homes in the 1950s. ...
[31]
[PDF] Chapter 5 Mass, Bernoulli, and Energy Equations
We are to explain how and why a siphon works, and its limitations. Analysis. Siphoning works because of the elevation and thus pressure difference between ...
[32]
[PDF] 1 Solution to the simple siphon problem - Duke Physics
Begin by applying Bernoulli's theorem to the top of the fluid in the left container AND to the bottom right hand side of the tube. The pressure at the.
[33]
[PDF] Forces on a Siphon 1 Problem 2 Solution - Kirk T. McDonald
Oct 29, 2024 · This argument is often stated as an application of Bernoulli's law to the (quasisteady) flow of liquid in the siphon. and H is the height of ...
[34]
[PDF] Design and Validation of a Siphonic Hydropower Systems Tool
The following sections explain the derivation of flow through a siphon using Bernoulli's principle, modifications to this derivation due to loss factors ...
[35]
[PDF] 6. Flow of Fluid and Bernoulli's Equation
The velocity of flow from the nozzle, and therefore the volume flow rate delivered by the siphon, depends on the elevation difference between the free surface ...Missing: formula | Show results with:formula
[36]
[PDF] Fluid Flow in Pipes (Single-pipe) - C
Frictional losses in piping are commonly evaluated using the Darcy–Weisbach or Hazen–Williams equation. The Darcy– Weisbach formulation provides a more ...
[37]
Pumps and siphons
Therefore Ptop = P1 = 1 atm - ρh1g on the left side, and Ptop ... When you flush, the water first rises in the bowl above the highest point in the siphon.Missing: maximum rho
[38]
The height limit of a siphon | Scientific Reports - Nature
Dec 2, 2015 · The maximum height of a siphon is generally assumed to be dependent on barometric pressure—about 10 m at sea level.
[39]
Atmospheric Pressure vs. Elevation above Sea Level
The table below indicates air pressure at elevations below and above sea level. Atmospheric Pressure vs. Elevation above Sea Level. Altitude, Absolute Barometer ...<|control11|><|separator|>
[40]
Negative Pressures and the First Water Siphon Taller than 10.33 ...
Apr 7, 2016 · Recently a siphon using an ionic liquid was demonstrated to transfer liquid from one container to another inside a vacuum chamber [21]. This ...
[41]
[PDF] Contact Angle and Wetting Properties - Jingwei Zhu
More specifically, a contact angle less than 90° indi- cates that wetting of the surface is favorable, and the fluid will spread over a large area on the ...Missing: siphon cavitation
[42]
[PDF] Contact Angle
Other solid/liquid combinations such as water on teflon or mercury on glass have a contact angle that is greater than π/2 as sketched on the right in Figure 2.
[43]
Cavitation - The Engineering ToolBox
Cavitation occurs in fluid flow systems where the local static pressures are below the fluids vapor pressure.Missing: siphon incompressible inclination<|separator|>
[44]
[PDF] Define vapor pressure and its significance Discuss cavitation and its ...
The viscosity of gases increases with temperature, while the viscosity of liquids decreases with temperature, as illustrated in the figure. • For water, µ ...Missing: siphon operation incompressible
[45]
An investigation of flow characteristics in slope siphon drains
Jan 1, 2014 · In siphon drainage, the pressure of liquid gradually decreases with the increasing elevation over the liquid surface of the nozzle. Thus, during ...
[46]
[PDF] HYDRAULIC MODEL STUDIES OF THE SIPHON AND FEEDER ...
A circular siphon outlet, capable of priming with a tailwater ele vation in the feeder-canal transition corresponding to that for two pumps operating and with ...
[47]
Siphon Break Phenomena Associated With Pipe Leakage Location
Jun 15, 2022 · Leakage above the hydraulic grade line and close to the top inverted U section of the siphon pipe ultimately leads to the siphon breakage.Missing: interior uniform
[48]
[PDF] Principles of Siphons With Respect to the Artificial-Recharge Studies ...
Pressure reduction in the injection line due to the siphon effect causes the release of dissolved gases and cavitation of the recharge water. This is another ...
[49]
[PDF] Construction of Automatic Bell Siphons for Backyard Aquaponic ...
Jun 10, 2010 · A hole is drilled in the capped end of the bell, and an air tube is inserted into the hole. This air tube, or “snorkel,” acts as a means to ...Missing: setup | Show results with:setup
[50]
[PDF] Design, Use and Installation of Dosing Siphons for On-site ...
Automatic dosing siphons are nothing new. They've been used for 100 years or more to flush livestock yards, in sewage treatment plants to dose trickling ...
[51]
Dosing Siphons | American Manufacturing Company, Inc.
An inexpensive, trouble-free method of providing dosing and resting is through the use of an automatic siphon.
[52]
Cycles Per Hour with Bell Syphon - aquaponics - Reddit
Mar 27, 2023 · Mine is cycling filling and draining every 3-4 min, so about 15 to 20 times per hour. Is this overkill? I have a 1 inch stand pipe, so I need ...How often is a good cycle time for an flood and drain system?Bell Siphon Demonstration : r/engineeringMore results from www.reddit.comMissing: example 10L
[53]
Siphon Spillways - ASDSO Dam Safety Toolbox
Siphon spillways have been used to help pass excess inflows (ie, augment other hydraulic structure discharge capacity).
[54]
[PDF] Siphon Spillway
A siphon spillway is practical when large capacity is not needed and space is limited. It maintains water surface elevation and acts as an overflow at low flow.
[55]
Inverted Siphons - Texas Department of Transportation
Inverted Siphons. Inverted siphons carry flow under obstructions such as sanitary sewers, water mains, or other structure or utilities that may be in the ...
[56]
[PDF] Urban Drainage Design (HEC-22) 4th edition - ROSA P
This manual provides a comprehensive and practical guide for the design of storm drainage systems associated with transportation facilities.
[57]
[PDF] 34.1 Siphon Spillway - NPTEL Archive
Siphons in size and surplussing capacity constructed- were: (i) flow conditions and pressure distribution, and limit,. (ii) vibrations, and. (iii) effect of ...
[58]
Design of Inverted Siphon (With Diagram) | Sewer | Sanitary ...
Design an inverted syphon of a total length of 80 m, to he provided for a 100 cm diameter sewer. The discharges which it has to carry are 0.72 cu.m./sec., 0.31 ...
[59]
CS700H-L: Heated Rain Gage - Campbell Scientific
The CS700H contains an internal siphon mechanism that causes precipitation to flow at a steady rate to the tipping bucket mechanism (regardless of intensity).
[60]
Tipping Bucket vs. Siphon Precipitation Gauges - R.M. Young
A tipping bucket rain gauge consists of a small bucket mounted on a pivot. As rain falls into the bucket, it fills up until it reaches a set weight—typically ...
[61]
The Flush Mechanism - How Toilets Work | HowStuffWorks
A good portion of the water flows down to a larger hole at the bottom of the bowl. This hole is known as the siphon jet. It releases most of the water directly ...
[62]
Toilet Buying Guide - American Standard
Toilets that use less water are better for the environment. Toilets that utilize less than 6L of water qualify as a high efficient toilet.
[63]
The Soda Siphon - Summit Sips
Jul 5, 2010 · A soda siphon is a pressurized container for dispensing carbonated water, allowing you to release only the amount you need, keeping it cold and ...
[64]
Handbook of Meteorology/Mercury Barometers - Wikisource
Oct 13, 2021 · —A common form of the barometer is a siphon tube, the short arm of which is enlarged to a bulb, and this constitutes the mercury cistern.
[65]
Evolution of Water Lifting Devices (Pumps) over the Centuries ...
The Mesopotamians were known to lift water using the shaduf at around 3000 BC [6]. The shaduf was widely spread in the ancient world, and several ancient ...
[66]
[PDF] The Story of the Pump, fu and Its Relatives - IRC
In the times of both Gallileo and Heron, who lived about 1800 years apart, pumps were quite often referred to as siphons, and in many instances a siphon meant a ...Missing: misnomers | Show results with:misnomers
[67]
The History of Pumps: Through the Years
Dec 22, 2011 · The history of pumps is long and illustrious. This account represents highlights of some of the major historical and technological developments.
[68]
Backflow Preventer Types - NFPA
Oct 28, 2022 · Air gaps can be used to protect low and high hazards under both back siphonage and backpressure. An Atmospheric Vacuum Breaker Assembly contains ...
[69]
[PDF] Methods and Devices for the Prevention of Backflow and Back ...
An air gap, although an extremely effective backflow preventer when used to prevent back siphonage and backpressure conditions, does inter- rupt the piping flow ...
[70]
https://www.pumpsandsystems.com/history-pumps-through-years
[71]
Vacuum Breakers - Watts
Designed for use in health hazard cross connections and continuous pressure applications where the water enters the equipment at or below its flood rim.
[72]
How Does An Anti-Siphon Valve Work? - Sprinkler School
When the valve shuts off, the anti-siphon mechanism kicks in. Anti-siphon valves utilize a small air vent or vacuum breaker that reacts to changes in pressure.
[73]
Understanding Backflow Prevention and Why It Matters
Vacuum breakers have a check valve that causes an air vent to open when your system's pressure drops. When the air vent opens, it breaks the vacuum and seals ...
[74]
Anti-siphon device on outside faucets? - InterNACHI®️ Forum
Apr 2, 2006 · An anti-siphon device (or vacuum breaker) prevents unsanitary water from being pulled back through a garden hose and contaminating your water system.
[75]
CHAPTER 6 WATER SUPPLY AND DISTRIBUTION
The IPC provides minimum regulations for plumbing facilities in terms of both performance and prescriptive objectives, and provides for the acceptance of ...
[76]
Safe Drinking Water Act (SDWA): A Summary of the Act and Its Major ...
Jul 1, 2021 · First enacted in 1974 and substantially amended in 1986, 1996, and 2018, the act is administered by the U.S. Environmental Protection Agency ( ...<|separator|>
[77]
[PDF] INTERNATIONAL PLUMBING CODE CHANGES ...
The requirements for backflow protection within the new harmonized standard remain the same as was in the ASME A112.18.1 standard. Presently. Section 608.15 of ...
[78]
Reduced Pressure Zone Assemblies - Watts
Designed for use in health hazard cross-connections and continuous pressure applications subject to backpressure or backsiphonage incidents.009 · LF009 · 957 · LF909 LargeMissing: trap primers industrial
[79]
Reduced Pressure Backflow Preventer | Model 375 - Zurn
The 375 Reduced Pressure Principle Backflow Assembly is utilized where a potential high health hazard exists and is ideal for use when lead-free valves are ...
[80]
Trap Primers | PrimePerfect - Sioux Chief
Debris screen with large openings to prevent clogging from sediment and debris. Activates with a 10 PSIG pressure drop at operating pressure of 30–150 PSIG.
[81]
Picking the right trap seal primer for your needs - Mifab
It only requires a 3 PSI line pressure drop to activate the primer. The opening range for all of MIFAB's M-500 Series of trap seal primers is 20 to 80 PSI. Even ...
[82]
Vacpot Syphon: The History & Brewing Guide - Perfect Daily Grind
Oct 9, 2015 · A syphon uses a vacuum to move coffee between chambers, combining immersion and filter brewing for a full-bodied, clear cup.
[83]
Brewing Siphon Coffee [History & Guide]
It was patented under Marie's rather impressive-sounding stage name Madame Vassieux. This patent that was filed in 1841 in Lyons, France was the invention that ...
[84]
https://mifab.com/picking-the-right-trap-seal-primer-for-your-needs/
[85]
[PDF] Inverted Siphon Design:
Identify the systems anticipated flow rates. 2. Determine inlet/outlet elevations & required capacity. 3. Determine siphon size and elevations.
[86]
How do I design an inverted siphon? - ResearchGate
Dec 3, 2015 · Length of Siphon = 400 m (57 m (in down slope) + 71m (horizontal) +132ft (sloping down)+100 m horizontal+40m (steep slope up)) see in the ...
[87]
Pythagorean Cup: Practical Joke Chalice Overflows with Ancient ...
Dec 23, 2016 · Cross section of a Pythagorean cup being filled: at B, the cup may be safely drunk from, but at C, the siphon effect causes the cup to drain.
[88]
Heron's Fountain | UCSC Physics Demonstration Room
The air filling container 3 is displaced by the denser water flowing down from the top, and rises up through the tube connecting container 3 to container 2.Missing: ancient trap
[89]
DIY Venturi Aquarium Vacuum Wand - DIY Wednesday - YouTube
Jan 11, 2017 · In this video I build and test a DIY aquarium vac wand which uses a water pump and a venturi siphon tee to pick up debris on a bare bottom ...
[90]
Karst Aquifers: Edwards Balcones Fault Zone Aquifer - USGS.gov
Jul 20, 2021 · The Edwards aquifer is the most transmissive of all the aquifers in Texas and Oklahoma, with large discharges from springs and from flowing and pumped wells.
[91]
(PDF) Drainage and siphoning of a karstic spring: A case study
Karst tidal springs refer to karst springs that are periodically discharged from groundwater under the control of special karst pipelines, also known as ...
[92]
Syphon Springs of Albania - ResearchGate
The syphon springs are ascending springs and also are called as vauclusian springs, after the famous Fontane de Vaucluse the source of river Sorgue in Province, ...Missing: siphon | Show results with:siphon
[93]
Flood Basins and Deltas (Chapter 7)
The Atchafalaya River, which forms at the apex of the delta, is geo-engineered to utilize an old meander bend cut-off to siphon ~30% of the Mississippi's ...
[94]
[PDF] karst hydrogeology of the upper suwannee river basin, alapaha river ...
The Cody Scarp (Escarpment) is a classic example of a karst escarpment with numerous poljes, uvalas, sinkholes, sinking streams, siphons, springs, and other ...
[95]
Karst Aquifers | U.S. Geological Survey - USGS.gov
The Edwards aquifer is the most transmissive of all the aquifers in Texas and Oklahoma, with large discharges from springs and from flowing and pumped wells.
[96]
A theoretical model for simulating periodic processes of Intermittent ...
Dec 21, 2022 · Intermittent karst springs (IKS) are common phenomena in karst areas where spring flow rates rise and fall in variable periods, ...
[97]
Study on Siphon Drainage Capacity of Slopes with Long-Horizontal ...
This paper investigates the performance of different pipe diameters in drainage capacity, flow regime, and restarting ability under different head and pipe ...
[98]
[PDF] Effects of surface water interactions with karst groundwater on ... - BG
Sep 12, 2024 · Abstract. Unearthing the effects of surface water and groundwater interactions on subsurface biogeochemical re-.
[99]
Pressure in the siphon - IOPscience
Jul 2, 2025 · The paper reports on direct measurements of pressure inside the siphon. Two apparatuses were designed. The first one allows for detailed measurements of ...
[100]
Calculation of the flow velocity of a siphon - AIP Publishing
Jan 8, 2021 · This study proposes new formulas, which can cover continuous and discontinuous flow and can consider the influence of the release of air from liquid on the ...
[101]
Siphon-based scalable and salt-resistant multistage thermal ...
Jan 5, 2025 · We propose siphon-based supply of saline water over the evaporator that enables scale up of the desalination system to a size significantly higher than the ...
[102]
Impact of Pipe Leakage Location on Siphon Flow Breakage
This paper investigates the hydrodynamic characteristics of the flow in a siphon under leakage (e.g., pipe puncture) and no-leakage conditions using the ...Missing: localization | Show results with:localization
[103]
Updated Design Standard for Siphonic Roof Drainage Systems Is ...
May 23, 2025 · ASPE/ANSI 45-2025 applies to engineered siphonic roof drainage systems intended to prime and operate full bore through proper pipe dimensioning.
[104]
Water infrastructure engineers confront an uncertain, changing climate
Mar 1, 2025 · Engineers recommend adjusting precipitation rates and volumes in hydrologic models to account for potential climate conditions.
[105]
Gravity-Driven Microfluidic Siphons: Fluidic Characterization and ...
Dec 2, 2021 · We introduce a microfluidic siphon concept that conceptualizes a multistep ′′dipstick′′ for quantitative, enzymatically amplified immunoassays.
[106]
NASA Supports Burst Test for Orbital Reef Commercial Space Station
Jul 25, 2024 · Teams conducted the burst test on Sierra Space's LIFE habitat structure using testing capabilities at NASA's Marshall Space Flight Center in ...Missing: siphon vacuum<|separator|>