16 AGZ 026B through 130B IOMM AGZ-5
Figure 17, AGZ 026 - AGZ 070, Typical Field Evaporator Water Piping
ir
Vent
Flow
Switch
Vibration
Eliminators
Drain
Outlet
Inlet
P
Isolation
Valves
Strainer
Thermowell
T
T
NOTE: Outdoor piping must be protected if freezing temperatures are a possibility.
Flow Switch
Mount a water flow switch in the leaving water line to shut down the unit when water
flow is interrupted. A flow switch is an equipment protection control and should never
be used to cycle a unit.
A “paddle” type flow switch is available from McQuay (part number 017503300).
Certain minimum flow rates are required to close the switch and are listed in Table 6.
Installation should be as shown in Figure 18. Connect the normally open contacts of
the flow switch in the unit control center at terminals 44 and 61. 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. Manufacturer’s instructions included with the switch should
be followed.
NOTE: Differential pressure switches are not recommended for outdoor installation.
They can freeze and not indicate a no-flow condition.
Table 6, Flow Switch Minimum/Maximum Flow Rates
Nominal Pipe Size
Inches (mm)
Minimum Required Flow To
Activate Switch - gpm (l/m)
Maximum Safe Flow Rate
gpm (l/m)
2 (50.8) 13.7 (51.8) 105 (397.4)
2 1/2 (63.50 17.9 (67.8) 149 (564.0)
3 (76.20 24.2 (91.6) 230 (870.6)
4 (101.6) 35.3 (134.0) 397 (1502.7)
5 (127.0) 48.6 (184.0) 654 (2475.4)
6 (152.4) 60.3 (228.0) 900 (3406.5)
Note: See pressure drop table on page 18 for minimum and maximum flow through the evaporator.
Figure 18, Flow Switch Installation
Flow direction marked on switch
1" (25mm) NPT flow switch
connection
Tee
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