Type 122A
4
Installation
!
WARNING
To avoid personal injury or equipment
damage caused by bursting of
pressure-retaining parts or explosion
of accumulated gas, do not exceed
the pressure or temperature limits
in Specifications and do not use the
Type 122A valve for installations where
water hammer can be experienced.
1. The switching valve may be installed in any
position. Position the vent (key 29, Figure 3) so
that the vent opening is facing downward. Protect
the vent opening against the entrance of moisture
or any other material that could plug the vent.
2. Apply pipe compound to external pipeline threads.
Connect piping to the body connections.
3. Connect the control pressure line to the 1/4 NPT
connection in the lower diaphragm case.
Overpressure Protection
Type 122A three-way switching valves have
maximum outlet pressure ratings that are lower than
their maximum inlet pressure ratings. A pressure-
relieving or pressure-limiting device is needed if inlet
pressure can exceed the maximum outlet pressure
rating. Overpressuring any portion of a switching
valve or associated equipment may cause leakage,
parts damage or personal injury due to bursting of
pressure-containing parts or explosion of accumulated
gas. Switching valve operation within ratings does
not preclude the possibility of damage from external
sources or from debris in the pipeline. A switching
valve should be inspected for damage periodically and
after any overpressure condition.
Startup and Adjustment
Key numbers is referenced in Figure 3.
1. With proper installation completed and
downstream equipment properly adjusted, slowly
open the upstream and downstream shutoff valve
(when used) while using pressure gauges to
monitor pressure.
!
WARNING
To avoid personal injury, property
damage or equipment damage caused
by bursting of pressure containing
parts or explosion of accumulated
gas, never adjust the control spring
to produce an outlet pressure higher
than the upper limit of the outlet
pressure range for that particular
spring. If the desired outlet pressure
is not within the range of the control
spring, install a spring of the proper
range according to the diaphragm parts
maintenance procedure.
2. Refer to the nameplate (key 25, Figure 3) for
the spring range. To change the spring setting,
loosen the locknut (key 30, Figure 3) and rotate
the adjusting screw (key 7, Figure 3). Rotating
the adjusting screw clockwise into the spring
case (key 1, Figure 3) increases the control
pressure at which the valve switches. Rotating
the adjusting screw counterclockwise decreases
the switching pressure.
Maintenance
Parts are subject to normal wear and must be
inspected and replaced periodically. The frequency of
parts inspection and replacement depends upon the
severity of service conditions.
Instructions are given below for complete disassembly
and assembly. Disassemble the valve only as far as
needed. Then, begin the “Assembly” procedure at the
appropriate step.
Key numbers used in these procedures are shown
in Figure 3.
!
WARNING
To avoid personal injury and equipment
damage caused by sudden release
of process pressure or uncontrolled
process fluid, isolate the valve from all
pressure and release all pressure from
the valve body and diaphragm casing
before attempting maintenance.
