Bulletin 71.7:167A November 1981
Type 167A Three-Way Switching Valve Introduction The Type 167A three-way switching valve (figure 1) is usually installed to provide switching or lock-up action in the event that system operation deviates from normal. The compact size and simplicity of this valve make it especially suitable for field or panel mounting.
Features • Convenient Installation—Compact construction permits easy handling and installation. • Easy, Accurate Adjustment—The switching point is set to a specific requirement by an adjusting screw atop the spring case.
W1947
Figure 1. Type 167A Three-Way Switching Valve
• Easy Maintenance—With the bottom piping disconnected, the valve can be completely disassembled without removing it from the line. CONTROL SPRING
Principle of Operation For the following operational sequence, refer to figures 2 and 3. The normal flow path, with no pressure applied to the diaphragm, is from connection A to connection C. As pressure is applied (connection D, figure 3), it registers under the diaphragm and opposes the spring. When the pressure under the diaphragm nears the spring setting, the pressure overcomes the spring, and moves the diaphragm assembly up. This allows the valve plug spring to lift the valve plug and provides flow through connection B. The flow path is then from connection A to connection B. When the pressure under the diaphragm decreases, the control spring moves the valve plug down and covers the opening to connection B.
VALVE PLUG
VALVE PLUG SPRING W0109-1
Figure 2. Sectional of Type 167A Three-Way Switching Valve
Table 1. Spring Selection SPRING RANGE, PSIG (bar) Panel Mounted
5 to 18 (0,3 to 1,2) 18 to 30 (1,2 to 2,0) 30 to 100 (2,0 to 6,9)
5 to 12 (0,3 to 0,8) 12 to 20 (0,8 to 1,4) 20 to 80 (1,4 to 5,5)
1B 986027212 1B 788327022 1K 748527202
SPRING COLOR CODE Green Silver Red
MAXIMUM PRESSURE CHANGE ON DIAPHRAGM FOR FULL STROKE, PSID (bar d) 5 (0,3) 8 (0,6) 15 (1,0) DD200077X012
Standard
SPRING PART NUMBER
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