Brass Foot Valve with Strainer

A foot valve is a non-return valve with an integral strainer, fitted at the bottom of the suction pipe of a centrifugal pump. It holds the column of liquid in the suction line when the pump stops, so the pump stays primed, and its strainer keeps debris out of the impeller. IS 4038:1986, the published specification for the type, describes exactly this duty: foot valves for use with centrifugal pumps for water works purposes.

This is the cast brass pattern: a compact one-piece body with a slotted strainer cage over the inlet and a female threaded socket at the outlet. The unit photographed is cast 3/4" and DN20 - the same size in two notations. Brass suits clean cold water, and this pattern is the usual choice for small irrigation, garden, booster and transfer pump sets, where the valve sits at the end of a hose or a short suction pipe in a tank, sump or well.

A foot valve on a suction lift works against a small pressure difference and is not a pressure-retaining component; it should not be substituted for a rated check valve on a discharge line. Sizing matters more than pressure. The valve and its strainer must not add so much head loss that the pump cavitates, so the free area through the strainer slots should be several times the bore of the pipe, and the valve should be kept clear of the floor and the sump walls so flow can reach it from all sides.

When ordering, state the nominal size; the thread form and that the end is female - BSP parallel to ISO 228-1, BSP taper to ISO 7-1 and NPT to ASME B1.20.1 are not interchangeable; the liquid and its temperature; and any requirement on strainer slot width. Confirm the seat and seal material and the working pressure with the supplier for the size actually stocked, because neither is stated in the catalogue record nor legible on the casting.