Spirax Sarco MkII, Safety And Operation

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IM-P157-38 CMGT Issue 4
8
Steam/Water Mixing Stations (MkII valves - 2002 onwards) Safety and Operation
2.2 Technical data
2.2.1 Minimum flow (to open the steam valve) and spring selection chart
(see Table 1)
A restricted outlet can cause back pressure, reducing the water flow through the mixing valve which may
prevent a sufficient amount of steam entering the mixing chamber.
The minimum flow for each size of mixing valve is shown in Table 1 below.
Note: when a valve supplies water against a back pressure a minimum pressure drop of approximately
1 bar (14.5 psi) is required across the mixing valve to allow the steam valve to lift off its seat.
Table 1
Size Spring
value
Spring
colour
code
*
Steam pressure Min. flow to
open steam
valve
Spring
notch
marking
psi bar kg/cm
2
g/min l/min
½"
High Y 100 - 150 7.00 - 10.3 7.14 - 10.51 1.0 4.5 Three
Medium G 50 - 100 3.50 - 7.0 3.57 - 7.14 0.6 2.7 Two
Low Bl 5 - 50 0.35 - 3.5 0.36 - 3.52 0.5 2.3 One
¾"
High R 100 - 150 7.00 - 10.3 7.14 - 10.55 1.8 8.2 Three
Medium B 50 - 100 3.50 - 7.0 3.57 - 7.14 1.5 6.8 Two
Low W 5 - 50 0.35 - 3.5 0.36 - 3.52 6.0 6.8 One
1"
High R 100 - 150 7.00 - 10.3 7.14 - 10.51 8.0 36.3 Three
Medium B 50 - 100 3.50 - 7.0 3.57 - 7.14 7.0 31.8 Two
Low W 5 - 50 0.35 - 3.5 0.36 - 3.52 6.0 27.2 One
1½"
High R 100 - 150 7.00 - 10.3 7.14 - 10.51 12.0 54.4 Three
Medium B 50 - 100 3.50 - 7.0 3.57 - 7.14 12.0 54.4 Two
Low W 5 - 50 0.35 - 3.5 0.36 - 3.57 12.0 54.4 One
*
Y = Yellow
G = Green
Bl = Black
R = Red
B = Blue
W = White