Data Sheet

Bulletin 71.7:167D
3
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
TANK PRESSURE
VACUUM PRESSURE
PRE-EXPANSION PRESSURE
INTERMEDIATE BLEED PRESSURE
PILOT SUPPLY PRESSURE
INTERMEDIATE PRESSURE
LOADING PRESSURE
BYPASS PRESSURE
BACK PRESSURE
PUMP PRESSURE
Figure 2. 167D Series Operational Schematics (Port D not shown)
INLET PRESSURE
OUTLET PRESSURE (WHEN LOADING PRESSURE IS LESS THAN SETPOINT)
OUTLET PRESSURE (WHEN LOADING PRESSURE IS EQUAL TO OR GREATER THAN SETPOINT)
ATMOSPHERIC PRESSURE
LOADING PRESSURE
OUTLET PRESSURE (WHEN LOADING PRESSURE IS LESS THAN SETPOINT)
INLET PRESSURE
OUTLET PRESSURE (WHEN LOADING PRESSURE IS EQUAL TO OR GREATER THAN SETPOINT)
ATMOSPHERIC PRESSURE
LOADING PRESSURE
TYPE 167DA THREE-WAY SWITCHING VALVE
CONTROL SPRING
PORT A
PORT C
PORT B
VALVE PLUG
O-RING
VALVE STEM
VALVE SPRING
BODY
ORIFICE SEAT
DIAPHRAGM
M1151
TYPE 167D TWO-WAY SWITCHING VALVE
M1152
ADJUSTING SCREW
DIAPHRAGM
VALVE PLUG
VALVE SPRING
PORT A PORT C
VALVE STEM
BODY
ORIFICE SEAT
O-RING
SOFT SEAT
CONTROL SPRING
OUTLET PRESSURE (WHEN LOADING PRESSURE IS LESS THAN SETPOINT)
INLET PRESSURE
OUTLET PRESSURE (WHEN LOADING PRESSURE IS EQUAL TO OR GREATER THAN SETPOINT)
ATMOSPHERIC PRESSURE
LOADING PRESSURE
Principle of Operation
Refer to Figure 2 and also refer to Figures 3 through
5 for port D location. Control pressure enters the
switching valves through Port D (not shown in Figure 2)
and registers under the diaphragm. Control pressure
overcomes the spring force and the diaphragm, and
raises the valve plug, closing port C and opening port
B of the Type 167DA three-way switching valve. In this
condition, the Type 167D construction is turned off and
the Type 167DA construction provides fl ow from path A
to B. If, either intentionally or through pneumatic failure,
the control pressure drops below the spring force, the
diaphragm and valve plug move downward, opening
port C and closing port B of the Type 167DA three-way
switching valve. In this condition both constructions
provide a fl ow path from port A to port C. The pressure
change necessary to switch the valve depends on the
spring used and the setting of the adjusting screw on the
switching valve.
Installation
The switching valve can be mounted in any position,
providing the vent in the spring case is free from
obstruction. Connect the pneumatic control line to
the port marked “D” on the valve body. Ports A and C
(and B on the Types 167DA and 167DAS valve) are
connected for the desired switching valve response to
loss or decrease in pneumatic pressure.
Figure 5 shows typical application of the Types 167DA
and 167DAS switching valve. If the control valve inlet
pressure falls below a predetermined setting, the on-
off controller turns off control pressure to the switching
valve. This causes the switching valve to bleed the
control valve diaphragm pressure to atmosphere, closing
the control valve. The control valve remains closed until
the inlet pressure is restored to the desired setting.
Dimensions are shown in Figure 7.
ADJUSTING SCREW