3-in-One Indicating gauge, low-limit and high-limit control
- set points and zero are easily adjusted on front of gauge
The Photohelic switch/gauge functions as versatile, highly repeatable pressure switches combined with a precise pressure gauge employing the time-proven Magnehelic gauge design. The Photohelic switch/gauge measures and controls positive, negative or differential pressures of air and compatible gases. Two phototransistor actuated, DPDT relays are included for low/high limit control. Easy to adjust setpoint indicators are controlled by knobs located on the gauge face. Individual setpoint deadband is one pointer width - less than 1% of full scale. Setpoints can be interlocked to provide variable deadband - ideal for control of fans, dampers, etc. Gauge reading is continuous and unaffected by switch operation, even during loss of electrical power. In typical applications, these switch/gauges control between high and low pressure set points. When pressure changes, reaching either set point pressure, the infrared light to the limiting phototransistor is cut off by the helix-driven light shutter. The resulting phototransistor signal 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. A plastic housing protects all electronic components. Solid-state and integrated circuit electronics are on glass-epoxy printed circuit boards and self-extinguishing terminal boards.<br><br>
Photohelic switch/gauges are used to control pressures in air conditioning systems, clean rooms, fluidic and pneumatic control systems, materials handling equipment, alarm or control fume exhaust systems, control pressure in air structures, and monitor respiratory and blood pressures.