News Details

About Valve leakage Introduce

Author: Date: 2014/7/27 19:49:11

Valve leakage refers to flow through a valve which is set in the 'off' state.

The importance of valve leakage depends on what the valve is controlling. For example, a dripping tap is less significant than a leak from a six-inch pipe carrying high-pressure radioactive steam.

In the United States, the American National Standards Institute specifies six different leakage classes, with "leakage" defined in terms of the full open valve capacity:

Class I, or 'dust-tight' valves, are intended to work but have not been tested

Class II valves have no more than 0.5% leakage with 50psi (or less if operating pressure is less) of air pressure at the operating temperature

Class III valves have no more than 0.1% leakage under those conditions; this may require soft valve seats, or lapped metal surfaces

Class IV valves have no more than 0.01% leakage under those conditions; this tends to require multiple graphite piston rings or a single Teflon piston ring, and lapped metal seats.

Class V valves leak less than 5*10^-12 cubic metres, per second, per bar of pressure differential, per millimetre of port diameter, of water when tested at the service pressure.

Class VI valves are slightly different in that they , and are required (at 50psi or operating pressure, whichever is less) to have less than a specified leakage rate in millilitres of air per minute:

Size	Leakage
1 inch	0.15 ml/min
1.5 inch	0.30 ml/min
2 inch	0.45 ml/min
2.5 inch	0.60 ml/min
3 inch	0.90 ml/min
4 inch	1.70 ml/min
6 inch	4.00 ml/min
8 inch	6.75 ml/min
10 inch	9 ml/min
12 inch	11.5 ml/min

Products Catagories

Flange End Valve Test Bench (9)

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H.P Safety Valve Test Bench (11)

Fluid and Gas Booster Unit (4)

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Planet Lapping Machine (1)

Ball Lapping Machine (1)

Seat Ring Lap Machine (0)

Portable Valve Grinder (5)

Valve Life and Torque Test Machine (0)

Container within Test Machine (0)

Contact Information

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Tel.: 0086-137 0588 0773
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Email: info@valvestest.com
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