035-19569-101 (0109)
4-6
GB
4.10 Stop Valves
Stop valves may be provided (by others) in the
evaporator and condenser water piping adjacent to
the unit to facilitate maintenance. Thermometer wells
and pressure taps should be provided (by others) in
the piping as close to the unit as possible to facilitate
operating check.
4.11 Flow Switches (Field Installed)
A fl ow switch or pressure differential control in the chilled
or condensed water lines is an accessory furnished for
connection to the control panel. If a fl ow switch is used,
it must be directly in series with the chiller and sensing
only water fl ow through the chiller. The fl ow switch can
be paddle type (fi eld installed) or thermal type (factory
mounted). A differential pressure switch that senses
pressure drop across the unit can also be supplied.
4.12 Drain and Vent Valves
Drain and vent valves (by others) should be installed
in the connections provided in the evaporator and
condenser liquid heads. These connections may be
piped to drain if desired.
4.13 Checking Piping Circuits and Venting Air
After the water piping is completed, but before any
water box insulation is applied. Tighten and torque (to
maintain between 41 and 82 Nm) the nuts on the liquid
head fl anges. Gasket shrinkage and handling during
Figure 4.4 Typical Refrigerant Vent Piping
transit may cause the nuts to loosen. If water pressure
is applied before tightening is done, the gaskets may be
damaged and have to be replaced.
Fill the chilled and condenser water circuits, operate
the pumps manually and carefully check the evaporator
and condenser water heads and piping for leaks. Repair
leaks as necessary.
Before initial operation of the unit both water circuits
should be thoroughly vented of all air at the high
points.
4.14 Refrigerant Relief Piping
Each unit is equipped with pressure relief valves located
on the condenser and on the evaporator for the purpose
of quickly relieving excess pressure of the refrigerant
charge to the atmosphere as a safety precaution in case
of an emergency, such as fi re. The pressure relief valve
is set at design pressure of the system and has discharge
capacity required by relevant standard.
Refrigerant relief vent piping (by others), from the relief
valves to the outside of the building, is required by code
in most areas and should be installed on all chillers. The
vent line should be sized in accordance with EN13136,
or local code. The vent line must include a dirt trap in
the vertical leg to intercept and permit clean out and to
trap any vent stack condensation. The piping MUST be
arranged to avoid strain on the relief valves, using a
fl exible connection, if necessary.
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