Dwyer 1950-0-2F Explosion Proof Differential Pressure Switch

Dwyer 1950-0-2F Explosion Proof Differential Pressure Switch (MPN: 195002F)

The Dwyer 1950-0-2F (order code: 195002F) is an explosion-proof differential pressure switch engineered for precise air and non-combustible compatible gas monitoring within classified hazardous marine and industrial locations. Combining the field-proven mechanical design of Dwyer’s Series 1900 with an integral, copper-free cast-aluminum enclosure, the 1950-0-2F delivers pressure switch capability in an assembly roughly half the weight and physical footprint of traditional explosion-proof switch enclosures.

Operating across a defined adjustable range of 0.15 to 0.50 in w.c. (37.3 to 124.4 Pa), the switch provides micro-differential sensitivity while maintaining robust mechanical isolation. It is UL listed, CSA certified, and FM approved for Class I (Div. 1 & 2, Groups C, D), Class II (Div. 1 & 2, Groups E, F, G), and Class III hazardous locations, as well as rated NEMA 3 (IP54 weather-resistant raintight), NEMA 7, and NEMA 9.

Model Details

• Manufacturer: Dwyer Instruments (DwyerOmega)
• Series: Series 1950 Explosion-Proof Differential Pressure Switch
• Full Model / Part Number: 1950-0-2F
• Alternate / Commercial Part Number (MPN): 195002F / 1950-0-2F-NA
• Operating Set Point Range: 0.15 to 0.50 inches water column (in w.c.)
• Deadband (Min Setpoint): ~0.10 in w.c.
• Deadband (Max Setpoint): ~0.15 in w.c.
• Enclosure / Construction: Integral Explosion-Proof Cast Aluminum with O-Ring Sealing and Vent Drain Plug

Technical Details

Features

1. Classified Hazardous Area Protection: Fully certified for Class I, Groups C & D; Class II, Groups E, F, G; and Class III, eliminating the need for bulky external explosion-proof junction boxes.
2. Ultra-Low Differential Span: Field-adjustable set point range of 0.15 to 0.50 in w.c. with an external adjustment screw located under a protective top cover.
3. Integral Weatherproof Cast Enclosure: NEMA 3 (IP54) raintight and weather-resistant housing featuring a captive-screw swing-away lid and built-in condensation vent drain plug.
4. High Electrical Contact Capacity: Heavy-duty SPDT snap-action switch contact rated up to 15 A at 125, 250, and 480 VAC, allowing direct line switching of interlocks, dampers, alarms, and intermediate relays.
5. Dual Port Pressure Sensing: Dual 1/8″ Female NPT taps for straightforward connection to metal pressure sensing lines in positive, negative (vacuum), or true differential pressure loops.

Direct System Compatibility

• Marine and offshore ventilation extraction ducts (gas detection interlocks)
• Marine combustion air supply fans (boiler/incinerator purge proving)
• Flue gas and exhaust duct fan trip assemblies
• Paint locker, battery room, and chemical storage continuous purge blowers
• Offshore platform HVAC air handler filter drop-off monitoring (AHUs)
• Industrial dust collector baghouse delta-P monitoring in combustible dust zones

Part Number Cross-References

• Dwyer: 1950-0-2F, 195002F, 1950-0-2F-NA
• Functional Predecessors / Equivalents: Dwyer 1900-0 with external NEMA 7 housing, Dwyer 1950G-0-B (ATEX/IECEx electronic relay generation)
• Cross-Industry Equivalents: Mercoid DPA series, United Electric (UE) 120 Series differential switches (comparable span variants)

Frequently Asked Questions

What is the operating differential pressure range of the Dwyer 1950-0-2F?

The Dwyer 1950-0-2F features an adjustable operating range between 0.15 and 0.50 inches water column (approx. 37.3 to 124.4 Pa), making it ideal for low-velocity ventilation, airflow interlocks, and draft proving applications.

Can the Dwyer 1950-0-2F be mounted horizontally on a deckhead or panel?

No. The 1950-0-2F must be mounted with its internal diaphragm in a strict vertical plane. Mounting the switch horizontally causes the weight of the diaphragm to induce mechanical offset, severely shifting both the setpoint and the reset deadband.

What is the maximum overpressure rating for this differential switch?

The continuous overpressure rating for the Series 1950 diaphragm is 45 inches water column (0.11 bar or 11.2 kPa). The switch can withstand brief surge pressures up to 10 psi (0.69 bar) without catastrophic diaphragm rupture, though sustained operation above 45 in w.c. must be prevented with overpressure snubbers.

How do you adjust the setpoint on the Dwyer 1950-0-2F?

Setpoint adjustment is made via the slotted screw located at the top of the enclosure housing. Turning the screw clockwise increases the setpoint pressure, while counter-clockwise rotation lowers the setpoint. Setpoint calibration should always be confirmed using a calibrated manometer and syringe pump.

Does the Dwyer 1950-0-2F require an intrinsic safety barrier?

Because the Dwyer 1950-0-2F utilizes a heavy, copper-free cast-aluminum explosion-proof (NEMA 7/9) enclosure, it can directly switch line-voltage loads up to 15 A without an external intrinsic safety (IS) barrier, provided all electrical wiring and conduit seal fittings adhere to Class I Div 1 code standards.