Series-1950

Supported Applications

The Series 1950 Explosion-Proof Differential Pressure Switch combines the features of the Dwyer Series 1900 Pressure Switch with an integral explosion-proof and weatherproof housing. It is totally rain-tight for outdoor installations and is used to sense differential pressure of air and non-combustible, compatible gases in hazardous locations.

• Explosion-proof differential pressure sensing in hazardous atmospheres
• Outdoor, rain-tight pressure switching
• Air and non-combustible, compatible gas service

Each unit is CE, UL and CSA listed and FM approved for use in Class I, Div 1, Groups C and D; Class II, Groups E, F and G; and Class III atmospheres, with an enclosure rating of NEMA 3 (IP54), NEMA 7 and 9. CAUTION: for use only with air or compatible gases; applications with hazardous atmospheres and a single positive pressure may require special venting.

Operating Conditions & Performance

The switch element is Single-pole double-throw (SPDT) with an electrical rating of 15 A @ 125, 250, 480 VAC, 60 Hz, and resistive ratings of 1/8 HP @ 125 VAC and 1/4 HP @ 250 VAC. Electrical connections are 3 screw type: common, normally open and normally closed. The process connection is 1/8" female NPT.

• Temperature limits: -40 to 60°C; 1950P-8, 15, 25 and 50 models are limited to -17.8 to 60°C, and the 1950-02 model to -34.4 to 54.4°C.
• Continuous pressure: 1950 models 45 in w.c. (0.11 bar); 1950P models 35 psi (2.41 bar); 1950P-50 only 70 psi (4.83 bar).
• Surge pressure: 1950 models 10 psi (0.69 bar); 1950P models 50 psi (3.45 bar); 1950P-50 only 90 psi (6.21 bar).
• Mounting: diaphragm in vertical position; set point adjustment is screw type on top of the housing.

Because of the restrictive effect of the flame arrestors, switch response time may be as much as 10-25 seconds where applied pressures are near the set point. The three-part aluminum housing weighs 3.25 lb (1.5 kg), with the 1950-02 model at 4.4 lb (2 kg). Wetted materials are consult factory.

Configuration Options

Models divide into two range families that let the switch be matched to the magnitude of the differential pressure being monitored, each ordered with the same explosion-proof housing and SPDT switch.

• 1950 (w.c. range) models cover low inches-of-water-column set points and carry a continuous rating of 45 in w.c. (0.11 bar).
• 1950P (psid range) models cover higher psid set points with a continuous rating of 35 psi (2.41 bar).
• 1950P-50 extends the highest range and is uniquely rated to 70 psi (4.83 bar) continuous and 90 psi (6.21 bar) surge.

Each model has a factory-set operating range with an approximate deadband that widens from the minimum to the maximum set point.

Key Product Differences

The model number is built as 1950-<range>-<suffix>, for example 1950-00-2F; a P designates PSID-range models while other models are in w.c. The inches-water-column models are:

• 1950-00-2F — 0.07 to 0.15 in w.c.
• 1950-0-2F — 0.15 to 0.5 in w.c.
• 1950-1-2F — 0.4 to 1.6 in w.c.
• 1950-5-2F — 1.4 to 5.5 in w.c.
• 1950-10-2F — intermediate in w.c. range model.
• 1950-20-2F — 4.0 to 20.0 in w.c.

The PSID-range models are:

• 1950P-2-2F — 0.5 to 2 psid
• 1950P-8-2F — 1.5 to 8 psid
• 1950P-15-2F — 3 to 15 psid
• 1950P-25-2F — 4 to 25 psid
• 1950P-50-2F — 15 to 50 psid