What is the maximum inlet pressure this standard covers?

The maximum permissible working pressure for the valve body is 1.6 MPa (approximately 16 bar) as per Clause 6.1.

What are the standard sizes for these PRVs?

The standard covers nominal sizes of 15, 20, 25, 32, 40, and 50 mm, as per Clause 4.1.

What material should a PRV body be made of?

The body should be made of Leaded-Tin Bronze (e.g., LTB 2 of IS 318) or other specified corrosion-resistant copper alloys as per Clause 3 and Table 1.

How is a PRV's performance tested?

It undergoes pressure tests (body and seat) and performance tests (pressure reduction and flow rate) as detailed in Clause 8.

IS 9739

: 1981

pressure-reducing valves for domestic water supply systems

CurrentSpecializedSpecificationBIMMEP · Sanitary Appliances and Water Fittings

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This standard specifies the requirements for materials, dimensions, construction, and performance of direct-acting, spring-loaded pressure-reducing valves (PRVs) for domestic water supply systems. It covers valves from 15mm to 50mm nominal size, intended for a maximum working pressure of 1.6 MPa, and outlines testing procedures to ensure their reliability.

pressure-reducing valves for domestic water supply systems

Quick Reference Values

Maximum permissible working pressure1.6 MPa

Hydrostatic body test pressure2.5 MPa

Hydrostatic seat test pressure1.7 MPa

Class 1 adjustable outlet pressure range0.1 to 0.4 MPa

Class 2 adjustable outlet pressure range0.3 to 0.8 MPa

Nominal sizes covered15 mm to 50 mm

Practical Notes

PRVs are critical in high-rise buildings and areas with high municipal supply pressure to protect downstream fixtures (taps, geysers, etc.) from damage.

Always install the valve in the correct orientation as indicated by the flow arrow on the valve body, typically with an upstream strainer and isolation valves.

Pressure creep (a slow rise in outlet pressure under no-flow conditions) can indicate a worn-out seat or diaphragm requiring maintenance or replacement.