What is the acceptable accuracy error margin for domestic water meters?

±2% in the upper flow zone (Qt to Qmax) and ±5% in the lower flow zone (Qmin to Qt).

What nominal sizes of water meters are covered by IS 779?

It covers nominal sizes of 15, 20, 25, 40, and 50 mm.

What is the maximum operating pressure and temperature for these meters?

Standard meters are designed for a maximum working pressure of 1.0 MPa (10 bar) and a maximum temperature of 45°C.

IS 779

: 1994

Copper alloy gate, globe and check valves for waterworks purposes - Specification

CurrentFrequently UsedSpecificationBIMMEP · Water Supply and Plumbing

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IS 779 provides specifications for domestic water meters of nominal sizes 15 mm to 50 mm. It covers the material requirements, dimensions, flow performance characteristics, and testing procedures to ensure accurate volumetric measurement of cold potable water.

Specifies requirements for copper alloy gate, globe, and check valves used in waterworks and general piping applications.

Quick Reference Values

Nominal sizes covered15 mm to 50 mm

Maximum working pressure1.0 MPa (10 bar)

Maximum water temperature45°C

Accuracy limit (Lower zone - Qmin to Qt)± 5%

Accuracy limit (Upper zone - Qt to Qmax)± 2%

Pressure tightness test limit1.6 MPa for 15 minutes

Practical Notes

Ensure the meter is installed in the correct orientation (horizontal/vertical) as improper alignment significantly affects accuracy.

Always install a line strainer upstream of the meter to protect the measuring mechanism from suspended debris.

Avoid exposing domestic cold water meters to temperatures above 45°C to prevent damage to internal plastic components.