Control systems Self-acting controls
4
1
Capacities
2
3 4 5
10
4 5
10
4.5 81
20
30 40 50
100
200
Example of how to use the capacities chart Where: - Example load = 20 kg/h - Upstream gauge pressure 5 bar = 6 bar abs. Method: - Draw a horizontal line from 6 bar abs. - Draw a horizontal line from 20 kg/h
- Drop a vertical line from the 6 bar x critical pressure crossing point until it crosses 20 kg/h horizontal. - The Kv for valve selection is given at this crossing point as Kv 0.3 - From the P-band table below a ¾" valve has 4 °C P-band.
Kv at P-band in °C Size 1 °C
2 °C
4 °C
6 °C
8 °C
Maximum lift K v 0.55 at 15 °C Xp
For conversion: Cv (UK) = Kv x 0.963 Cv (US) = Kv x 1.156
½" ¾"
0.18
0.22
0.27
0.29
0.32
0.20
0.23
0.29
0.29
0.33
0.87 at 15 °C Xp
Operating temperature at design Kv = Set value - Xp
TI-P350-01 CTLS Issue 5
Page 3 of 4
TA10A and TA10P Steam Tracing Temperature Control Systems
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