7
Model 288A 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 aff ected.
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 Section 5, page 34. See Appendix A for
Model 224 DPU installation and maintenance information.
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.
Table 2.1, page 8, shows switch and relay wiring color coding for legacy and
current confi gurations. 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 and setpoint repeatability are infl uenced by various ap-
plication 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: Field calibrations and switch setpoint testing should be performed at
the same application conditions as expected when the instruments are
required to perform their safety functions. Performance testing at one ap-
plication condition may not necessarily ensure appropriate performance
at another condition.