How do I adjust the pressure switch on the Model B-1 Pressure Maintenance Device?
The pressure switch used on the Model B-1 pressure maintenance device is a Furnas Model 69H. Removing the cover, one finds two adjustment screws: a large metallic screw for adjusting the cut-in pressure (the pressure at which the compressor comes on as system pressure decreases); and a small metallic screw for adjusting the cut-out pressure (the pressure at which the compressor shuts off on rising pressure. Turn the large screw clockwise to increase both cut-in and cut-out pressure, and turn the small screw clockwise to increase the cut-out pressure without affecting the cut-in pressure. Procedure Wire the compressor and B-1 pressure maintenance device pressure switch in accordance with the wiring diagram. Start with no pressure and energize the circuit. The compressor should start immediately. Allow the compressor to run until it shuts down, recording the pressure reading. This is the current cut-out pressure setting. Next, bleed the air pressure out of the system, watching the air pr
