What is the primary function of a foot valve?

It is installed at the bottom of a pump suction line to act as a check valve, preventing water from draining back into the sump and thereby maintaining pump prime.

What is the minimum required open area for the foot valve strainer?

The strainer's total open area must be at least 1.5 times the cross-sectional area of the valve's nominal bore to minimize head loss.

What are the hydrostatic testing requirements for these valves?

The valve body must withstand a hydrostatic pressure of 1.5 MPa, while the seat is tested for leak-tightness at the maximum working pressure (typically 1.0 MPa).

IS 4038

: 1986

foot valves for water works purposes

CurrentSpecializedSpecificationBIMWater Resources · Sanitary Appliances and Water Fittings

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This standard specifies the requirements for materials, dimensions, construction, and testing of flanged and screwed foot valves used in water works. These valves are essential for maintaining pump prime and preventing backflow in suction lines.

foot valves for water works purposes

Quick Reference Values

size range flanged50 mm to 450 mm

size range screwed25 mm to 150 mm

hydrostatic test pressure body1.5 MPa

hydrostatic test pressure seat1.0 MPa (or maximum working pressure)

minimum strainer open area1.5 times the nominal bore area

Practical Notes

Foot valves should ideally be installed vertically to ensure the flap or disc seats properly under its own weight and water pressure.

Always verify the total open area of the strainer before installation; an inadequate open area will cause severe head loss and potential pump cavitation.

Periodic cleaning of the strainer is required, especially in raw water or muddy water applications, to prevent clogging.