Dwyer 3320 3000 Photohelic Pressure Switch / Gage

Dwyer Instruments, 3304, 3000 Photohelic Pressure Switch / Gage, 10 - 0 - 10 Zero Center Inches of Water

The Photohelic Switch / Gage is a very versatile, precise pressure switch combined with the time-proven Magnehelic pressure gage. Gage reading is unaffected by switch operation. Easy to adjust set points have knob controls. Applied pressure and switch set points are fully visible at all times. Deadband is one pointer width - less than 1% of full scale. Double-pole double-throw relays can be easily interlocked to provide variable deadband control.

Photohelic Gage Sensing. In a typical control application, the Photohelic switch / gage controls between high and low pressure set points. When pressure changes, reaching either set point pressure, the beam from an LED to the limiting phototransistor will be cut off by the helix-driven light shield. The resulting signal change is electronically amplified to actuate its DPDT slave relay and switching occurs. Dead band between make and break is 1% of full scale or less - just enough to assure positive, chatter-free operation.