Type 122A
2
Specifications
The Specifications section lists the specifications for Type 122A three-way switching valve. Factory specification is
stamped on the nameplate fastened on the valve at the factory.
Table 1.
Set Pressure Ranges
SET PRESSURE RANGES
PRESSURE BUILD-UP
ABOVE SETPOINT
REQUIRED FOR
FULL STROKE
SPRING
WIRE DIAMETER
SPRING
FREE LENGTH
SPRING PART
NUMBER
SPRING
COLOR
psig
bar
psi
bar
In.
mm
In.
mm
3 to 15
5 to 20
5 to 35
0.21 to 1.0
0.35 to 1.4
0.35 to 2.4
10
13.5
22
0.69
0.93
1.5
0.168
0.187
0.218
4.27
4.75
5.54
2.94
2.81
2.50
74.6
71.4
63.5
1D892327022
1D751527022
1D665927022
Red
Cadmium
Blue
30 to 60
40 to 100
60 to 150
2.1 to 4.1
2.8 to 6.9
4.1 to 10.3
30
54
66
2.1
3.7
4.6
0.234
0.283
0.240
5.94
7.19
6.10
2.57
2.31
2.63
65.2
58.7
66.8
1D7455T0012
1E543627142
1P901327142
Green
Yellow
Brown
Maximum Inlet Pressure
(1)
150 psig / 10.3 bar
Set Pressure Ranges
(1)
See Table 1
Maximum Control Pressure to Diaphragm
(1)
150 psig / 10.3 bar
Temperature Capabilities
(1)
-20 to 150°F / -29 to 66°C
Flow Coefficients
C
g
(2)
Connection A to B:
138
Connection A to C:
131
C
1
Connection A to B:
28.0
Connection A to C:
32.5
Control Connection
1/4 NPT
Approximate Weight
5 lbs / 2.3 kg
1. The pressure/temperature limits in this Instruction Manual and any applicable standard or code limitation should not be exceeded.
2. At an inlet pressure of 25 psig / 1.7 bar and with full pressure drop across the body.
Principle of Operation
Refer to Figure 2. The flow through the Type 122A valve
is normally from port A to C, with the spring force holding
the valve plug down on port B (diverging service).
As the pressure under the diaphragm is increased
through port D, it acts against the force of the spring.
When the control pressure overcomes the force of
the spring, the valve begins to stroke, opening port B.
Once the pressure under the diaphragm reaches
setpoint plus build-up, the valve completes its stroke
and the port C seat ring is closed. The valve will only
fully stroke when build-up above setpoint is achieved.
The point at which the valve completes its stroke
and the pressure change necessary to do this are
dependent on the spring rate and the set point
chosen. The set pressure is easily changed by
adjusting the screw at the top of the valve.
