The A3000 Series Photohelic differential pressure switch/gauge adopts the reliable and durable Magnehelic design concept, combining a high-precision differential pressure gauge and a high-repeatability differential pressure switch. It can measure and control the positive pressure, negative pressure or differential pressure of air or other compatible gases. The standard pressure withstand level is 25 psig (1.7 bar), and options of 35 psig (2.4 bar) or 80 psig (5.5 bar) pressure withstand are also available. The 36000S single-pressure type can measure up to 6000 psig (413 bar) and withstand pressure up to 9000 psig (620 bar). Two double-pole double-throw switches are used for high/low limit control. The knobs on the instrument panel can easily adjust the set points, and the deadband of each set point is less than 1%, narrower than the width of the pointer. Using two set points can lock out different deadbands, which is most suitable for controlling fans, dampers, etc. The differential pressure gauge reading is not affected by the switch operation, and the reading is not affected even in case of power failure. The optional range is from 0 - 0.25 inches of water column (0 - 6 mm of water column) to 30 psi (2.1 bar).

The working principle of Photohelic

When the differential pressure changes between the high and low set point values and reaches a certain set point, the linked light-shielding plate will block the infrared light beam directed at the limit transistor, so that the transistor signal is amplified and triggers the action of the double-pole double-throw switch.

Features

The engineering plastic shell protects all electronic components and circuits. The solid-state switches and electronic components are fixed on the circuit board protected by epoxy resin and are equipped with flame-retardant terminal blocks.

● The dial and frame (with set point knobs and zero adjustment screw holes) can be opened to see the structure of the Photohelic differential pressure gauge/switch. The dial is made of transparent polycarbonate plastic.

● The pointer and the light shutter are balanced and installed on the spiral shaft. According to different pressures, the light shutter can be driven to pass through the card slot of the optical limit switch, so that the built-in infrared light source shines on the phototransistor or is blocked.

● The light-shielding protection can effectively prevent external light from entering to avoid affecting the internal phototransistor, and the instrument pointer can rotate freely. The design is reasonable, beautiful and generous.

● The optical limit switch has high reliability and long service life. It is directly attached to the pointer and aligned respectively to ensure accurate switch actions.

● The flexible drive shaft is connected to the set point adjustment knob.

● The zero adjustment screw is connected to the screw on the dial to adjust the pressure reading.

● The plastic shell protects the electronic components and electrical connections.

● The polycarbonate plastic connectors or terminal blocks are flame-retardant.

● The glass epoxy printed circuit board is stable, durable and has good performance.

● The load relay uses a double-pole double-throw switch with locking, which has a wide range of applications.

● The circuit system is designed for 50/60 Hz, 120VAC, and the allowable fluctuation range is 10% of the voltage. Other voltage options can be specially customized.

● The pointer of the switch setting always indicates the position of the set point.

● The spring friction coupling can prevent the set point adjustment device from being over-adjusted and damaged.

● The three-in-one instrument integrates multiple instruments into one product, saving inventory, installation time and costs.

● The overall design and 1% full-scale dead zone provide a fast response to pressure changes, meaning the switch operates without delay and without flutter.

● Various models can meet the pressure measurement requirements from low to high.