Omega PSW20 User Manual

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PSW20 Series

Pressure, vacuum or differential pressure switches

INSTRUCTION

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M4067-0504

Installation Instructions for OMEGA PSW20 Series: Pressure, Vacuum and Differential

Pressure Switches.

General

The PSW20 series is single pole switch that can be used as a pressure or vacuum switch (from 0.40 in W. C. to
20 inches W. C.) or as a pressure differential switch. The switch can respond to rapid pulsing and the gold
plated silver contacts will handle low level switching currents.

Mounting Instructions

Switch may be mounted in horizontal or vertical position, through 0.12" (3mm) holes on 1.34" (34mm)
centerline, with suitable clearances to accommodate 0.15" I.D tubing and electrical connectors – see diagram
for dimensions.

Electrical, Pneumatic and Material/Mechanical Specification

Part
Number

Pressure range

(inches water, gauge)

Pressure Vacuum Differential
PSW20A 0.4-15 0.4-15 .04-15
PSW20B 1-20 1-20 1-20

Standard

Electrical rating

Number

PSW20A 750ma

PSW20B 1 amp

Body Acetal
Diaphragm EPDM is standard; Nitrile

Contacts Gold plated silver
Springs Plated phosphor bronze
Terminals Plated copper or brass
Adjusting screw Stainless steel or zinc plated SS
Weight 9 grams (0.3oz)
Operating temperature -30 C to +65 C (-23F to 149F)
Listings UL recognized for 100,000

Max.

Resistive

250VAC

250

VAC

Min

Resistive

5 ma

3 VDC

5 ma

3 VDC

available. NOTE: EPDM should
not be used in petroleum
applications

operations
CSA certified

Repeat
AccuracyPart

Constant

Temperature

+/- 4% 0.04

+/- 3% 0.02

Contact
Resistance
(ohms)

Connections and Adjustment

Pressure Switching – Normally Open Contacts

Connect the pressure source to inlet port B (see diagram) and set the adjusting screw to the desired pressure.
Turning the screw clockwise narrows the gap between contacts and decreases the pressure set point. Turning the
pressure adjusting screw counterclockwise increases the set point. Note: the media entering the
diaphragm through Port B is separated from the electrical contacts by the diaphragm.

Pressure Switching – Normally Closed Contacts

Connect the pressure source to Port A and monitor continuity across the terminals. Slowly turn the adjusting
screw clockwise, narrowing the gap between contacts until the contacts are closed. Apply the set point pressure
which will open the contacts. Continue to turn the adjusting screw clockwise until the contacts
make and break at the desired point.

Vacuum Switching

Repeat the above procedure using Port A for Normally Open Contacts and Port B for Normally Closed
Contacts.