7
Model 289A Differential Pressure Indicating Switch
Section 2
Section 2—Installation
General
The instrument should be inspected at time of unpacking to detect any dam-
age that may have occurred during shipment.
IMPORTANT: The DPU was checked for accuracy at the factory. Do not change any of
the settings during examination or accuracy could be affected.
For applications requiring special cleaning/precautions, a polyethylene bag
is used to protect the instrument from contamination. This bag should be
removed only under conditions of extreme cleanliness.
Mounting/Piping/DPU Installation
Dimensional drawings are provided in
page 35.
See the Model 199 DPU
user manual in Appendix A for DPU installation and maintenance informa-
tion.
Electrical Connection (Switches/Relays)
Units are supplied with either single or dual alarm switches and/or relays
(depending on customer order). The direct-set switch contacts are adjustable
over 5% to 95% of the scale range for SPDT switches and 6% to 94% of the
scale range for DPDT switches.
Table 2.1, page 8,
shows switch and relay wiring color coding for legacy
and current configurations. Figures 2.1 through 2.6 show switch and relay
wiring.
The high switch and low switch set point adjustment procedures are covered
in
Changing Switch Set Point, page 22.
For physical location of switches, see
Figure 1.1, page 3
.
Switch Use
Switch contact life is influenced by various application conditions such as
temperature, humidity, airborne contamination, vibration, amount of plunger
travel, cycling rate, and rate of plunger travel (and others), as well as by the
electrical (circuit) characteristics.
IMPORTANT: Arc suppression for inductive loads will prolong the life of the switch
contacts.