Technical data

7.6.4 Refrigerant Charging
When opening any part of the refrigerant
system for repairs, the refrigerant charge
must be removed. If the chiller is equipped
with optional valves, the refrigerant can be
isolated in either the condenser or evaporator
/ compressor while making repairs.
To prevent liquid freezing within the cooler tubes when
charging an evacuated system, only refrigerant vapour
must be added to the system until the system pressure
is raised above the point corresponding to the freezing
point of the cooler liquid. For water, the pressure
corresponding to the freezing point is 58.9 kPa for
R134a (at sea level).
While charging, care must be taken to prevent
moisture laden air from entering the system.
Make up a suitable charging connection from new
copper tubing to fit between the system charging valve
and the fitting on the charging drum. This connection
should be as short as possible but long enough to permit
sufficient flexibility for changing drums. The charging
connection should be purged each time a new container
of refrigerant is connected and changing containers
should be done as quickly as possible to minimise the
loss of refrigerant.
7.7 Condenser and Cooler
Maintenance of condenser and cooler shells is
important to provide trouble free operation of the chiller.
The water side of the tubes in the shell must be kept
clean and free from scale. The following
recommendation should be followed in determining the
condition of the water side of the condenser and cooler
tubes.
1. The condenser tubes should be cleaned annually
or earlier if conditions warrant. If the temperature
difference between the water off the condenser
and the condenser liquid temperature is more than
4° greater than the difference recorded on a new
unit, it is a good indication that the condenser tubes
require cleaning.
2. The cooler tubes under normal circumstances will
not require cleaning. If however the temperature
difference between the refrigerant and the chilled
water increases slowly over the operating season,
it is an indication that the cooler tubes may be
fouling or that there may be a water by-pass in the
water box requiring gasket replacement or
refrigerant may have leaked from the chiller.
7.7.1 Chemical Water Treatment
Since the mineral content of the water circulated
through the cooler and condenser varies with almost
every source of supply, it is possible that the water being
used may corrode the tubes or deposit heat resistant
scale in them. Reliable water treatment will greatly
reduce the corrosive and scale forming properties of
almost any type of water.
As a preventive measure against scale and corrosion
and to prolong the life of cooler and condenser tubes, a
chemical analysis of the water should be made
preferably before the system is installed. A water
treatment expert should be consulted to determine
whether water treatment is necessary, and if so, to
furnish the proper treatment for the particular water
condition.
035L02381-GB0 7-5