Technical Instructions
Powermite 599 MT Series Terminal Unit 2-way Valves
Document Number 155-196P25
April 9, 2009
Page 8
Siemens Building Technologies, Inc.
2-in Pneumatic
A
2W NC
2W NO
B
1/2",
Cv < 1.6
1/2",
Cv < 4
3/4" and 1"
Cv<10
Line Size (in)
Differential Pressure (psi)
Differential Pressure (kPa)
2W, NC, 10 - 15 psi
SQS...
Line Size (in)
Differential Pressure (psi)
Differential Pressure (kPa)
50
(345)
95
(655)
40
(276)
1/2",
Cv>0.4
Cv < 1.6
1/2",
Cv>2.5
Cv < 4
3/4" and 1"
2W, NC, SQS...
90
80
70
60
50
40
30
20
10
0
100
621
552
483
414
345
276
207
138
69
0
690
Line Size (in)
180
160
140
120
100
80
60
40
20
0
Differential Pressure (psi)
Differential Pressure (kPa)
85
(586)
160
(1103)
70
(483)
2W, NO, SQS...
1241
1103
966
828
690
552
414
276
138
0
1/2",
Cv>0.4
Cv < 1.6
1/2",
Cv>2.5
Cv < 4
3/4" and 1"
Line Size (in)
Differential Pressure (psi)
Differential Pressure (kPa)
45
(310)
95
(655)
35
(241)
2W, NO, 3 - 8 psi
1/2",
Cv < 1.6
1/2",
Cv < 4
3/4" and 1"
Cv<10
90
80
70
60
50
40
30
20
10
0
100
621
552
483
414
345
276
207
138
69
0
690
VF0319R1
SSC...
Line Size (in)
Differential Pressure (psi)
Differential Pressure (kPa)
50
(345)
95
(655)
40
(276)
1/2",
Cv>0.4
Cv < 1.6
1/2",
Cv>2.5
Cv < 4
3/4" and 1"
2W, NC, SSC...
90
80
70
60
50
40
30
20
10
0
100
621
552
483
414
345
276
207
138
69
0
690
Line Size (in)
Differential Pressure (psi)
Differential Pressure (kPa)
65
(448)
120
(828)
55
(379)
2W, NO, SSC...
1/2",
Cv>0.4
Cv < 1.6
1/2",
Cv>2.5
Cv < 4
3/4" and 1"
120
100
80
60
40
20
0
140
828
690
552
414
276
138
0
996
50
(345)
95
(655)
40
(276)
90
80
70
60
50
40
30
20
10
0
100
621
552
483
414
345
276
207
138
69
0
690
Figure 2. Close-off Pressures.
Operation
Figure 3 shows the normally open valve in the open or full flow position and the
normally closed valve in the closed or zero flow position. The valve spring provides the
necessary force to hold the stem in the raised or normal position.
In the event of power failure, a spring return actuator returns the valve to its normal
position. Non-spring return actuators will hold the last commanded position. See the
Technical Instructions of the various actuators for additional information.
VF0209R1
NORMALLY CLOSED
NORMALLY OPEN
Figure 3.
Sizing
The sizing of a valve is important for correct system operation. An undersized valve will
not have sufficient capacity at maximum load. An oversized valve can initiate cycling,
and the seat and throttling plug can be damaged because of the restricted opening.
Correct sizing of the control valve for actual expected conditions is considered essential
for good control.
See Tables 3 through 6 for valve capacities.
