Foot Valve

A foot valve is a type of check valve installed at the bottom of a pump suction line, typically submerged in the fluid source such as a tank, sump, well, or open water intake. Its primary function is to maintain the pump's prime by preventing backflow when the pump is not operating, while a built-in strainer basket filters out debris and particulates that could damage the pump impeller or internal components.

How It Works

When the pump starts, suction pressure lifts the internal check element — either a hinged flap or a poppet disc — off its seat, allowing fluid to flow freely into the suction line. When the pump stops, the check element falls back onto its seat under gravity and back-pressure, sealing the line and keeping it primed with fluid. The surrounding strainer basket prevents solids, leaves, sand, and other debris from entering the valve and the pump system.

Check Mechanism Types

Hinged Flap: A pivoting disc or flap swings open on a hinge when flow is present and closes by gravity when flow stops. Suitable for larger pipe sizes and moderate flow velocities.

Poppet Check: A spring-loaded or gravity-seated disc lifts axially off its seat to allow flow and reseats quickly when flow ceases. Offers a tighter seal and faster response, commonly used in smaller sizes and higher-pressure applications.

Typical Applications

Foot valves are widely used across a broad range of industries and installations:

• Water supply tanks and storage reservoirs
• Sumps and drainage pits
• Irrigation and agricultural water intake systems
• Industrial process pumping and chemical transfer
• Fire protection and sprinkler system suction lines
• Borehole and shallow well pump installations

Materials

Foot valves are available in a variety of body and strainer materials to suit different fluid types and operating environments:

• Cast Iron Body: Robust and cost-effective for general water and non-corrosive fluid service.
• PVC Body: Lightweight and corrosion-resistant, ideal for chemical applications, seawater, and aggressive media.
• Stainless Steel Strainer Screen: High durability and corrosion resistance for demanding or hygienic applications.
• Plastic Strainer Screen: Economical option suitable for clean water and light-duty service.

Connection Types and Size Range

Foot valves are available with threaded (BSP/NPT) or flanged end connections to suit a wide range of piping systems. Standard sizes range from 3/4" for small domestic or light commercial pump installations up to 8" for large industrial or municipal water intake applications.

Installation Tips

• Install the foot valve vertically at the lowest point of the suction line, fully submerged in the fluid source.
• Maintain a minimum submersion depth (typically 300–600 mm) to prevent air ingestion and vortexing.
• Ensure the strainer basket is sized appropriately — the open area should be at least 3–4 times the pipe cross-sectional area to minimise pressure drop.
• Use thread sealant or appropriate gaskets on all connections to prevent air leaks that could break pump prime.

Maintenance Notes

• Inspect and clean the strainer basket periodically — frequency depends on the level of debris in the fluid source.
• Check the seating surface and check element for wear, corrosion, or damage; replace seals and discs as needed.
• If the pump loses prime frequently, inspect the foot valve for a worn or damaged check element that may not be sealing correctly.
• Replace the foot valve if the body shows signs of cracking, heavy corrosion, or if the strainer basket is deformed beyond cleaning.