Cameron BARTON 289A - Section 1-Introduction; General

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Model 289A Differential Pressure Indicating Switch Section 1
Section 1—Introduction
General
The weatherproof Model 289A is a differential pressure indicating switch.
The Model 289A has a NEMA-4 watertight die-cast aluminum case (nished
with a weather-resistant black epoxy resin paint). The cover lens is secured in
the bezel with an elastomer ring to reduce the possibility of accidental break-
age. This ring also acts as a seal between the bezel and the case to ensure a
moisture, fume and dust-free atmosphere for the indicator and switch mecha-
nism. The large cover lens allows maximum readability of the indicating
pointer.
Switches and all adjustments are readily accessible when the cover is re-
moved.
The built-in switches energize either single or dual alarm circuits when the
measured differential pressures exceed predetermined limits. These limits
may be either maximum, minimum, or both.
MainComponents
Low Alarm
Relay
Plunger
Screw
Switch
Lock
Low Alarm
Switch
Actuating
Cam
High Alarm
Switch
Switch
Lock
Plunger
Screw
Differential
Drive
Arm
High Alarm
Relay
Hex Hub
Zero
Adjust
Switch Link
Movement
Assembly
High Alarm
Switch
Adjust
Range
Adjust
Pointer
Low Alarm
Switch
Adjust
Terminal
Strip
Stop Screw
Stop Screw
Figure 1.1—Switch components