User Guide

Technical Instructions SW 134 Pressure Electric Switch (Adjustable Differential)
Document Number 155-050P25
April 1, 2005
Page 2 Siemens Industry, Inc.
Warning/Caution Notations
WARNING
Personal injury/loss of life may occur
if you do not perform a procedure as
specified.
CAUTION
Equipment damage, or loss of data
may occur if you do not perform a
procedure as specified.
Application
These pressure electric switches are used wherever it is necessary to close (or open) an
electrical circuit on the basis of a predetermined air pressure signal. This switch should
be used in areas protected from the weather. Typical applications include the control of
air compressors, fans, pilot lights, and resistance heating elements.
WARNING:
The pressure electric switches are designed for use only as an operating
control. Where an operating control failure would result in personal injury
and/or loss of property, it is the installer’s responsibility to add devices
(safety, limit controls) or systems (alarm, supervisory systems) that
protect against, or warn of control failure.
Specifications
Medium Compressed air
Setpoint range 3 to 30 psig (20 to 200 kPa)
Differential Adjustable from 1.5 to 20 psig (10 to 138 kPa)
Switch DPST, snap acting
Maximum pressure 50 psig (345 kPa)
Pressure connection 1/8-inch male NPT
Electrical ratings See Table 1
Conduit opening 1/2-inch conduit
Ambient temperature 32 to 140°F (0 to 60°C)
Weight 2 lb (0.9 kg)
Dimensions See Figure 3
Approval (for 134-1450 only) UL file E 35198
Operation
Model 134-1450
Model 134-1451
The pressure electric switch incorporates a non-metallic diaphragm, which is positioned
by air pressure changes, to actuate a heavy-duty electrical contact mechanism.
When signal pressure is equal to or greater than setpoint pressure, switch contacts are
closed. When signal pressure is below setpoint pressure an amount equal to or greater
than the differential pressure, switch contacts are open.
When signal pressure is equal to or greater than setpoint pressure, switch contacts are
open. When signal pressure is below setpoint pressure an amount equal to or greater
than the differential pressure, switch contacts are closed.