Series 1950G Explosion-Proof Switch combines the best features of the popular Dwyer® Series 1950 Pressure Switch with the benefit of natural gas compatibility. Units are rain-tight for outdoor installations, and are UL listed for use in Class I, Groups A, B, C, & D; Class II, Groups E, F, & G and Class III atmospheres, Directive 2014/34/EU (ATEX) Compliant for CE ATEX II 2G Exd IIB+H2 T6, CSA & FM approved for Class I, Div. 1, Groups B, C, D; Class II, Div. 1, Groups E, F, G and Class III atmospheres IECEx Ex d IIB+H2 T6 (-40°C < Ta < +60°C). The 1950G is very compact, about half the weight and bulk of equivalent conventional explosion-proof switches.

Product Applications

• Natural gas applications
• Process applications
• All-weather applications

Explosion-proof Series H3 Explosion-Proof Differential Pressure Switch, heavy duty, industrial unit has a unique new design which provides sensitivity to differential pressures as low as 10 inches of water (254 mm w.c.), yet handles total pressure of 1500 psi (103 bar). Unlike common differential pressure switches that use a piston-type motion transfer, the Series H3 utilizes a rotary motion transfer shaft that prevents a change in total pressure from causing a setpoint shift. Unit yields deadbands approximately 5% of range, with zero setpoint shift due to variation in working pressures. Friction is minimized and repeatability increased by allowing range spring to act directly on diaphragm plate. Rolling diaphragm design maintains constant effective area to further reduce friction. Diaphragm is allowed to “seat”, allowing application of full rated pressure, up to 1500 psi (103 bar), on either high or low pressure port, without damage. Special over-travel feature prevents overtightening of range adjust screw.

Product Applications

• Water flow proving with an orifice plate.
• Differential pressure across chiller.
• Liquid filter status.
• Perfect for monitoring differential water pressure on filters, chiller coils, and flow elements.

Product Applications

• Mechanical HVAC or process equipment
• Chemical, petroleum, food and drug processing industries
• Process and Industrial applications

Customers tell us that the Series DA/DS Bourdon Tube Pressure Switches are the best pressure switches made. The Mercoid DA/DS Series is one of the world’s broadest lines of pressure switches. The DA/DS Series has extremely high sensitivity and great repeatability. The DA Models are equipped with two external adjustments, one for setting high pressure operating point, the other for setting low pressure operating point. Deadband, the difference between high and low setpoints, is adjustable over the full-scale. The DS Models are equipped with a single external adjustment for setting operating point only. For mercury-free switches, choose between the snap action switch or hermetically sealed snap action switch. Hermetically sealed mercury switch also available.

Product Applications

• Compressors
• Mechanical HVAC or process equipment
• Pump control

Large sensitive diaphragm and reliable, time proven mechanical design are combined in Series PG Gas Pressure/Differential Pressure Switches. For use with air and other compatible gases, they feature excellent ±1% of full scale repeatability, clear easy-to-read scale and convenient external setpoint adjustment.

Application flexibility is assured by a large variety of switching options including SPST, SPDT, DPST and DPDT; opening or closing on increasing pressure, vacuum or differential. PR and PRL models add manual reset operation on increasing or decreasing pressure. Mercury switches or hermetically sealed snap switches are available where high humidity would be a problem. If vibration or other factors preclude the use of mercury, snap switches can be provided. Standard housing is NEMA 1. Optional enclosures can be supplied for weather resistant and explosion-proof requirements.

Product Applications

• Natural, manufactured or LP gas applications

Reliable and convenient, the Series 1996 Gas Pressure Switches serve as a compact, low cost switch for gas fired furnaces and equipment. Pressure ranges for both models are ideal for high or low gas pressure interlock. Visible set point and on-off indicators add convenience in servicing. Use either NO or NC contacts on SPDT switch. Bottom connection has both 1/8" female and 1/4" male threads for pipe nipple or coupling. Top connection vents diaphragm chamber to outside or to furnace combustion chamber. Mount switch with diaphragm in a horizontal position and gas pressure connection at bottom. Used with natural, manufactured or LP gas.

Series 1996 Gas Pressure Switch - Compact, Low Cost, Range 1.4-20' w.c.

Model 1996-20 (Left view with label showing)

Product Applications

• Gas furnaces
• Natural, manufactured or LP gas applications

Our most popular Differential Pressure Switch is now available in a flame-proof ATEX/IECEx approved package in the Series AT11910. This pressure switch combines advanced design and precision construction to make these switches able to perform many of the tasks of larger, costlier units. For air and non-combustible compatible gases, the AT11910 Series switches have set points from 0.07 to 20 in w.c. (1.8 to 508 mm). Set point adjustment is easy with range screw located inside the switch enclosure. Series AT11910 ATEX/IECEx enclosures are available in aluminum enclosures and ideal for low pressure, hazardous area applications.

Important notes for installation:
• Cables must be fitted through 1/2" NPT cable gland or ATEX/IECEx conduit (not supplied with instrument).
• Make sure after cabling to close tight cover and cable gland, in order to keep IP66 rating (IP65 with option OPV, overpressure relief valve).
• Open cover only after de-energizing instrument.
• Attention: Check local safety rules and warnings on unit and manual for a correct use of the instrument in hazardous area.

Please see Series 1900 for non-ATEX/IECEx approved.

Product Applications

• Hazardous area low pressure applications
• Air conditioning refrigeration coil icing detection; defrost cycle initiation
• Clogged filter detection
• Variable air volume controller

The ATEX/IECEx approved Series AT1ADPS Adjustable Differential Pressure Switch is designed for pressure, vacuum, and differential pressure applications in hazardous areas. The dual scaled adjustment knob in inches water column and pascals allows changes to the switching pressure to be made without a pressure gage. The switch is available with settings from 0.08 in w.c. (20 Pa) up to 16 in w.c. (4000 Pa). The silicone diaphragm makes this series ideal for use with air and other noncombustible gases. Flame-proof enclosures are available in aluminum and can include a glass window for viewing set point status on the adjustment knob.

Important notes for installation:
• Cables must be fitted through 1/2" NPT cable gland or ATEX/IECEx conduit (not supplied with instrument).
• Make sure after cabling to close tight cover and cable gland, in order to keep IP66 rating (IP65 with option OPV, overpressure relief valve).
• Open cover only after de-energizing instrument.
• Attention: Check local safety rules and warnings on unit and manual for a correct use of the instrument in hazardous area.

Please see SERIES ADPS for non-ATEX/IECEx approved.

Product Applications

• Hazardous area pressure switch
• Air filter and ventilator monitoring
• Ventilation duct monitoring
• Industrial cooling circuits
• Fan heater overheating protection
• Fire-protection damper control
• Heat exchanger frost protection

Essential for industrial environments, the ATEX/IECEx approved Series AT21823 combines small size with 2% repeatability. Set point adjustment inside the switch allows for set point settings across 9 ranges from the low of .07 in w.c. to a maximum 85 in w.c. differential pressure. Series AT21823 flame-proof enclosures are available in aluminum and are ideal for low pressure hazardous area applications. Various housing options such as an overpressure relief valve or external setpoint adjustment knob are available. External setpoint knob allows adjustment without opening the enclosure.

Important notes for installation:
• Cables must be fitted through 1/2" NPT cable gland or ATEX/IECEx conduit (not supplied with instrument).
• Make sure after cabling to close tight cover and cable gland, in order to keep IP66 rating (IP65 with option OPV, overpressure relief valve).
• Open cover only after de-energizing instrument.
• Attention: Check local safety rules and warnings on unit and manual for a correct use of the instrument in hazardous area.

Please see Series 1800 for non-ATEX/IECEx approved.

Product Applications

• Hazardous area pressure switch
• Process applications
• Mechanical equipment control

Using solid state technology, the Series AT23000MR/AT23000MRS ATEX/IECEx Approved Photohelic® Switch/Gages combine the functions of a precise, highly repeatable differential pressure switch with a large easy-to-read analog pressure gage. Gage reading is unaffected by switch operation and will indicate accurately even if power is interrupted. AT23000MR series employ versatile electromechanical relays with low amperage ratings-ideal for dry circuits. For applications requiring high cycle rates, choose AT23000MRS models with SPST (NO) solid state relays. Easy to adjust set point indicators are controlled by knobs located on the gage face (accessible opening case after de-energizing instrument). All models provide both low and high limit control. Compatible with air and other non-combustible, non-corrosive gases, they can be used in systems with pressures to 25 psig (1.725 bar). Optional construction is available for use to either 35 psig (2.42 bar) or 80 psig (5.51 bar).

Important notes for installation:
• Cables must be fitted through 1/2" NPT cable gland or ATEX/IECEx conduit (not supplied with instrument).
• Make sure after cabling to close tight cover and cable gland, in order to keep IP66rating (IP65 with option OPV, overpressure relief valve).
• Open cover only after de-energizing instrument.
• Attention: Check local safety rules and warnings on unit and manual for a correct use of the instrument in hazardous area.

Please see SERIES 3000MR/MRS for non-ATEX/IECEx approved.

Product Applications

• Hazardous area pressure measurement and switching
• Pneumatic conveying
• Air conditioning systems
• Clean rooms
• Fume exhaust systems

Flame-proof ATEX/IECEx approved Series AT3A3000 Photohelic® Switch/Gages, function as versatile, highly repeatable pressure switches combined with a precise pressure gage employing the time-proven Magnehelic® gage design. The Photohelic® switch/ gage measures and controls positive, negative or differential pressures of air and compatible gases. Standard models are rated to 25 psig (1.7 bar) with options to 35 psig (2.4 bar) or 80 psig (5.5 bar). Two phototransistor actuated, DPDT relays are included for low/high limit control. Easy to adjust set point indicators are controlled by knobs located on the gage face (accessible opening case after de-energizing instrument). Set points can be interlocked to provide variable dead band– ideal for control of fans, dampers, etc. Gage reading is continuous and unaffected by switch operation, even during loss of electrical power. Flame-proof enclosures are available in aluminum with glass window which allows for viewing of set point needles and process pressure.

Important notes for installation:
• Cables must be fitted through 1/2" NPT cable gland or ATEX/IECEx conduit (not supplied with instrument).
• Make sure after cabling to close tight cover and cable gland, in order to keep IP66 rating (IP65 with option OPV, overpressure relief valve).
• Open cover only after de-energizing instrument.
• Attention: Check local safety rules and warnings on unit and manual for a correct use of the instrument in hazardous area.

Please see SERIES A3000 for non-ATEX/IECEx approved.

Product Applications

• Hazardous area pressure measurement and switching
• Air conditioning systems
• Clean rooms
• Fume exhaust systems