Vacuuming And Charging - McQuay M5RT 90 BR Technical Manual

Vacuuming And Charging

The rooftop package units are factory pre-charged with sufficient refrigerant. However, there may be a need
for charge recovery during service and maintenance works. Therefore, some precautions must be taken to
ensure optimum and trouble-free system operation:
(i) The system should be throughly vacuumed to ensure no incompressible gas and moisture in the system.
(ii) Use a vacuum pump for R410A exclusively. Using the same vacuum pump for different refrigerants may
damage the vacuum pump or the unit.
(iii) The refrigerant should never be released directly into the environment.
(iv) When charging R410A, ensure that only liquid is being withdrawn from the cylinder or can.
Dip-pipe
Normally, the R410A cylinder or can is equipped with a dip-pipe for liquid withdrawal. However, if the dip-pipe
is not a vailable, invert the cylinder or can so as to withdraw liquid from the valve at the bottom.
n
R410A must be charged as liquid. Usually R410A cylinder is equipped with a dip-pipe for liquid withdrawal. If there is no dip-pipe,
the cylinder should be inverted so as to withdraw liquid R410A from the valve.
n Do not top-up when servicing leak, as this will reduce the unit performance. Vacuum the unit thoroughly and then charge the
unit with fresh R410A according to the amount recommended in the specification.
Invert cylinder
without dip-pipe
Liquid
withdrawal
CAUTION
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