IOMM ACZ/AGZ-1 9
Figure 5, Typical Evaporator Field Water Piping
Flow Switch
Mount a water flow switch in either the entering or leaving water line to shut down the unit when
water flow is interrupted.
A flow switch is available from McQuay (part number 017503300). It is a “paddle” type switch and
adaptable to any pipe size from 3” (76mm) to 8” (203mm) nominal. Certain minimum flow rates are
required to close the switch and are listed in Table 3. Installation should be as shown in Figure 6.
Connect the normally open contacts of the flow switch in the unit control center at terminals 5 and 6.
There is also a set of normally closed contacts on the switch that can be used for an indicator light or
an alarm to indicate when a “no flow” condition exists. Freeze protect any flow switch that is installed
outdoors.
NOTE: Differential pressure switches are not recommended for outdoor installation.
Table 3, Flow Switch Minimum Flow Rates
NOMINAL PIPE SIZE
INCHES (mm)
MINIMUM REQUIRED FLOW TO
ACTIVATE SWITCH - GPM (L/S)
1 (25.4) 6.00 (0.38)
1 1/4 (31.8) 9.80 (0.62)
1 1/2 (38.1) 12.70 (0.80)
2 (50.8) 18.80 (1.20)
2 1/2 (63.50 24.30 (1.50)
3 (76.20 30.00 (1.90)
4 (101.6) 39.70 (2.50)
5 (127.0) 58.70 (3.70)
6 (152.4) 79.20 (5.00)
Figure 6, Flow Switch Installation
Flow direction marked
on switch
1" (25mm) NPT flow
switch connection
Tee
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