Control valves

Pressure reducing/surplussing valves

Page 2 of 3

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Up stream pressure bar g

(x 100 = kPa)

4.6.3

Capacities for safety valve sizing

Full lift capacities for safety valve sizing purposes :

Size

Kvs

For conversions:

Cv (UK) = Kv x 0.963

Cv (US) = Kv x 1.156

Steam and compressed air capacities

DN15

1.5

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DN20

DN25

2.5

3.0

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Steam

capacity

kg/h

Compressed air

capacity dm

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/s*

free air

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��� 1" - DN25

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1⁄2"-DN15

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3⁄4" - DN20

1" - DN25

* dm

3

/s = I/s, 1 I/s2 c.f.m.

How to use the chart

The curved lines labelled 2, 3, 4, 5 etc., represent upstream pressures. Downstream pressures are read along the vertical line on the left

hand side of the chart.

How to use the chart is best described by an example:-

Required, a pressure reducing valve to pass 120 kg/h reducing from 8 to 6 bar. From the downstream pressure of 6 bar on the left

hand side of the chart extend out horizontally until the line meets the curved 8 bar upstream line. At this point read vertically downwards

where it will be seen that a 1⁄2" BRV2 will be required.

BRV2S and BRV2B SG Iron Pressure Reducing Valve

TI-P045-14 CH Issue 5

Page 2 of 3

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