PSW-850

Supported Applications

The Omega PSW-850 Series consists of general-purpose industrial pressure switches designed to actuate or de-actuate one, two, or three snap-acting switches at pre-determined set points. These mechanical control devices are intended for industrial applications requiring multiple switching capabilities. Documented application functions include alarm and shutdown, pre-alarm and alarm signaling, high/low limit monitoring, and level staging.

Triple-switch models within the series support liquid level control configurations where three pressure settings correspond to specific elevations in a sump pump system (e.g., pumping out). The units are manufactured in the USA and feature internal adjustments via knobs, pointers, or screws depending on the model type.

Operating Conditions & Performance

The PSW-850 Series operates across a pressure range of 30 inHg Vacuum to 3000 psi. Specific standard ranges include -300 to 0 inH₂O, -10 to +10 inH₂O, and various positive pressure spans up to 200 to 3000 psi. Setpoint repeatability is ±2% of the adjustable range for most models; model PSW-852E exhibits a repeatability of ±3% of the adjustable range.

Ambient operating temperature ranges from -40 to 70°C (-40 to 160°F), with an exception for model PSW-852A, which operates from -40 to 70°C (0 to 160°F). Setpoint shift is typically less than 1% of range for a 30°C (54°F) ambient temperature change. Storage temperature limits are specified as -54 to 71°C (-67 to 158°F).

Performance under mechanical stress includes setpoint repetition after shock events of 15 g, 10 ms duration, and vibration exposure of 2.5 g at frequencies from 5 to 500 Hz.

Configuration Options

• Switch Outputs: Configurable for 2 or 3 SPDT switches. Switches can be separated up to 100% of the range span, except models PSW-852A and PSW-852B which allow separation up to 30%. Wiring options include 'normally open' or 'normally closed'.
• Electrical Ratings: Rated for 15 A at 125/250/480 Vac resistive. Electrical connections are made via three 22 mm (⅞") diameter knockouts, with a maximum recommended wire size of 14 AWG.
• Housing & Enclosure: Die-cast aluminum housing that is epoxy powder coated and gasketed with captive cover screws. The enclosure complies with NEMA 1 requirements. Overall dimensions are 102 H x 125 W x 140 mm D (4 x 4.9 x 5.5"); maximum height including the pressure port is 210 mm (8.25").
• Process Connections: Standard connection is ¼ FNPT, except model PSW-852A which utilizes a ½ FNPT fitting.
• Approvals: UL and CE compliant.

Configuration Options

The series supports various wetted materials depending on the specific sensor element selected. Available options include BUNA-N diaphragm, 316 SS diaphragm, sealed brass bellows, welded 316L SS bellows, and a 303 SS piston. Sealing is provided by FKM O-rings or BUNA-N O-rings.

Key Product Differences

The PSW-850 Series includes distinct model families differentiated by switch count and adjustment mechanism:

• Type PSW-852, 853 Controls: Feature internal screw adjustments.
• Type PSW-855, 856 Controls: Utilize cam assemblies for internal calibrated adjustments. Triple-switch models (PSW-853 and PSW-856) include a reference dial.

Dual switch controllers omit the middle switch assembly, while single switch controllers omit the outer switch assemblies. Proof pressure ratings vary by model range; examples include 100 psi for low-pressure inH₂O models (PSW-852AA through AF), 225 psi for ranges up to 100 psi (models BI, BK, BL), and up to 10,000 psi proof pressure for high-range models PSW-852EO and EP.

Deadband settings are range-dependent. For instance, model PSW-852AA (-300 to 0 inH₂O) offers a deadband of 0.2 to 8 inH₂O, while model PSW-852AD (0.5 to 5 inH₂O) provides a deadband of 0.1 to 0.3 inH₂O.