Type 167A
Fisher Controls
Instruction Manual Type 167A Three-W ay Switching Valve
R
September
1980
Form 1932
INTRODUCTION Scope of Manual This instruction manual includes installation, adjustment, maintenance, and parts information for the Type 167A three-way switching valve (see figure 1).
Description The Type 167A is a compact, three-way switching valve usually installed to provide lock-up action should the system operation deviate from normal (see figure 2). This valve can be field or panel mounted. In the installation example shown in figure 3, the supply or control pressure is applied to the switching valve diaphragm through port D. As long as the supply pressure on the diaphragm overcomes the opposing spring, the switching valve plug will be in the up position allowing the positioner signal to flow from port A to port B and into the actuator diaphragm case. If the supply pressure decreases sufficiently, the switching valve plug will stroke down. Positioner pressure than flows from port A to port C. Since port C is plugged, the positioner pressure is isolated from the actuator. Port B is blocked with pressure locking the actuator upon loss of supply pressure.
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Figure 1. Type 167A Three-W ay Switching
The Type 167A is preadjusted at the factory according to the operating conditions specified on the order. However, should these conditions change, the switching valve can be easily readjusted by turning a single screw.
Specifications Specifications for the Type 167A valve are shown in table 1. eFisher Controls International, Inc. 1980; All Rights Reserved
AE5378-B A2425-1
Figure 2. Typical Switching
Valve Schematic
Valve