44
Control systems Pressure reducing/surplussing valves
Capacities for safety valve sizing
Size DN15 (½")
DN20 (¾")
DN25 (1")
For conversions: Cv (UK) = Kv x 0.963 Cv (US) = Kv x 1.156
Full lift capacities for safety valve sizing purposes:
Kvs
1.5
2.5
3.0
Steam and compressed air capacities
10 (145)
11 (160)
12 (174)
13 (189)
17 (189)
8.6 (125) 8 (116)
8 (116)
7 (102)
7 (102)
6 (87)
6 (87)
5 (73)
5 (73)
Upstream pressure bar g (psi g) (x 100 = kPa)
4 (58)
4.6 4
4 (58)
3 (44)
3 (44)
2 (29)
2 (29)
1 (15)
40 (88) 50 (110) 70 (154)
140 (309) 100 (220) 80 (176)
210 (463) 150 (331) 120 (265)
280 (618) 200 (441) 160 (353)
350 (772) 250 (551) 200 (441)
420 (926) 300 (661) 240 (529)
350 (772) 280 (617)
½" - DN15
Steam capacity kg/h (lb/h)
¾" - DN20
490 (1080)
1" - DN25
10 (21)
20 (42)
30 (64)
40 (85)
50 (106)
60 (127)
70 (148)
80 (170) 100 (212)
90 (191)
100 (212)
½" - DN15
Compressed air capacity dm 3 /s (cfm)* free air
90 (191)
10 (21)
20 (42)
30 (64)
40 (85)
50 (106)
60 (127)
70 (148)
80 (170)
110 (233)
120 (254)
¾" - DN20
20 (42)
40 (85)
60 (127)
80 (170)
100 (212)
120 (254)
140 (297)
160 (339)
180 (381)
1" - DN25
* dm 3 /s = I/s, 1 I/s d 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 ½ " BRV2 will be required.
TI-P045-14 CTLS Issue 8
Page 4 of 6
BRV2S and BRV2B SG Iron Pressure Reducing Valve
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