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Control systems Pressure reducing/surplussing valves
Steam capacities chart
4.6 136
Upstream pressure bar
DN15LC
DN15
DN20
DN25
DN32
DN40
DN50
DN80
How to use the chart Saturated steam
A valve is required to pass 600 kg/h reducing from 6 bar to 4 bar. Find the point at which the curved 6 bar upstream pressure line crosses the horizontal 4 bar downstream pressure line. A perpendicular dropped from this point gives the capacities of all DP sizes under these conditions. A DN32 valve, is the smallest size which will carry the required load. Superheated steam Because of the higher specific volume of superheated steam a correction factor must be applied to the figure obtained from the chart above. For 55 °C of superheat the factor is 0.95 and for 100 °C of superheat the factor is 0.9. Using the example given for saturated steam, the DN32 valve would pass 740 x 0.95 = 703 kg/h if the steam had 55 °C of superheat. It is still big enough to pass the required load of 600 kg/h.
TI-P004-01 CTLS Issue 8
Page 8 of 12
SDP143 Pilot Operated Pressure Surplussing Valve with Cast Steel Body
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