What is the required flow rate for a WC flush valve?

A minimum of 1.2 litres per second as per Clause 6.1.1.

What is the specified working pressure range for these flush valves?

They should operate satisfactorily between 0.05 and 1.0 MPa (0.5 and 10 bar) as per Clause 6.1.1.

How long should the flush last?

The duration of the flush should not exceed 7 seconds, according to Clause 6.1.1.

What material is specified for the valve body?

The body should be made from brass casting or hot pressing conforming to relevant IS codes like IS 319, as specified in Table 1.

How many cycles should a flush valve withstand in an endurance test?

The valve must withstand 50,000 cycles of operation without failure as per the endurance test in Clause 7.4.

IS 9758

: 1981

flush valves and fittings for water closets and urinals

CurrentFrequently UsedSpecificationBIMMEP · Sanitary Appliances and Water Fittings

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This standard specifies the material, construction, performance, and testing requirements for manually operated flush valves (flushometers) used with water closets and urinals. It covers aspects like flow rate, flush duration, and durability to ensure proper and efficient flushing in plumbing systems.

flush valves and fittings for water closets and urinals

Quick Reference Values

Minimum flow rate for WC flush valve1.2 L/s

Minimum flow rate for urinal flush valve0.4 L/s

Maximum duration of flush7 seconds

Recommended working pressure range0.05 to 1.0 MPa

Endurance test cycles50,000 cycles

Inlet connection size25, 32 or 40 mm nominal bore

Hydrostatic test pressure2.0 MPa

Practical Notes

Ensure the supply line pressure is within the valve's operating range (0.05 to 1.0 MPa) to prevent malfunction, incomplete flush, or water hammer.

Select valves specifically designated for either water closets or urinals as their required flow rates are significantly different.

The standard emphasizes the use of brass for the body, ensuring longevity and resistance to corrosion, which is a key quality indicator.