Operating instructions

Figure 18, AGZ 026BM - AGZ 070BM, Typical Field Evaporator Water Piping

Air

Vent

Flow

Switch

Vibration

Eliminators

Drain

Outlet

Inlet

Isolation

Valves

Strainer

Thermowell

Flow Switch (Model AGZ-BM)

Mount a water flow switch in the leaving water line of the remote water chiller 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 flow switch is available from McQuay (part number 017503300). It is a “paddle” type switch and

adaptable to any pipe size from 2” (51 mm) to 6” (152 mm) nominal. Certain minimum flow rates

are required to close the switch and are listed in

Table 7. Installation should be as shown in Figure

. 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.

Table 7, Flow Switch Minimum/Maximum Flow Rates

Nominal Pipe Size Minimum Required Flow To Maximum Flow Rate

Inches (mm) Activate Switch - gpm (l/m) 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 25 for minimum and maximum flow through the evaporator.

Figure 19, Flow Switch Installation

Flow direction marked on switch

1" (25mm) NPT flow switch connection

Tee

Water Connections

Bring water piping to the evaporator through the side between the vertical supports. Provide taps for

the connection of pressure gauges and thermometers in the inlet and outlet lines. Check the inlet and

outlet labels on the unit against the certified drawings supplied on the job and be sure the water

piping is hooked up correctly. Contact the McQuay sales office if any discrepancies exist.

16 ACZ / AGZ-BM IMM ACZ/AGZ-4