1900-10-MR Compact Low Differential Pressure Switches

Supported Applications

The Dwyer Series 1900 Compact Low Differential Pressure Switches are designed for air conditioning, fluidics, refrigeration, oven, and dryer applications. These switches monitor differential pressure in systems handling air and non-combustible, compatible gases.

Operating Conditions & Performance

The series operates within an ambient and process temperature range of -30 to 180°F (-34 to 82.2°C), with a humidity limit of 80% RH (non-condensing) and a maximum altitude of 6560 ft (2000 m). Pressure limits are rated for 45 in w.c. (11.2 kPa) continuous service, with a surge capability of 10 psig (68.95 kPa).

Performance specifications include repetitive accuracy within ±3%. The switches utilize a force-motion amplifier to increase the leverage of diaphragm movement for high sensitivity and repeatability. Mounting orientation requires the diaphragm in a vertical position; other orientations require consultation with the factory.

Configuration Options

The Series 1900 offers multiple configuration options to meet specific installation requirements, including housing types, reset mechanisms, and accessories.

• Housing Options: Standard models are intended for indoor use. Weatherproof housings (NEMA 4, IP66) feature a 16 ga. steel enclosure with a gasketed cover suitable for wet or oily conditions, passing a 200-hour salt spray test. Explosion-proof housings (NEMA 7, 9; NEMA 3) utilize a cast iron base with an aluminum or brass cover.
• Switch Types: Standard models provide automatic reset functionality via a Single-pole double-throw (SPDT) switch. A Manual Reset Option is available for single positive pressure applications on specific ranges, featuring a snap switch that latches upon pressure increase and requires manual intervention to reset after the setpoint drops.
• Electrical Ratings: The switches support 15 A @ 120-480 VAC (~), 60 Hz resistive loads. Motor ratings are specified as 1/8 HP @ 125 VAC and 1/4 HP @ 250 VAC, with a recommendation to derate to 10 A for high cycle rates.
• Process Connections: Standard units feature two 1/8" female NPT connections. Accessories include brass street ell adaptors (A-329) for right-angle installations and static pressure tips (e.g., A-302F-A, A-489).

Key Product Differences

The series is organized by operating range models, each with specific deadband characteristics:

• Model 1910-00: Range 0.07 to 0.15 in w.c.; Deadband approx. 0.04 at min/max set points.
• Model 1910-0: Range 0.15 to 0.5 in w.c.; Deadband approx. 0.10 at min/max set points.
• Model 1910-1: Range 0.40 to 1.6 in w.c.; Deadband approx. 0.15 (min) and 0.16 (max).
• Model 1910-5: Range 1.40 to 5.5 in w.c.; Deadband approx. 0.30 at min/max set points.
• Model 1910-10: Range 3.0 to 11.75 in w.c.; Deadband approx. 0.40 at min/max set points.
• Model 1910-20: Range 4.0 to 20.0 in w.c.; Deadband approx. 0.40 (min) and 0.50 (max).

Housing variations are indicated by model prefixes: standard models use the 1910 base, weatherproof options change the base to 1911 with a -WP suffix, and explosion-proof options use the 1911 base with an -EXPL suffix. Manual reset variants utilize the 1900 base number with an -MR suffix.