System design recommendations
Diameter of separate suction lines from
evaporators to condensing unit manifold should
be with appropriate size according evaporator
capacity (securing recommended speed for proper
oil return). Common manifold tube should be as
close as possible to condensing unit.
NOTICE
The installer is responsible for the
installation of the unit and complete refrigeration
system design according particular conditions
of each application as this is not scope of current
Guideline.
Moisture obstructs the proper functioning of both
the compressor and the refrigeration system. Air
and moisture reduce service life and increase
condensation pressure, which causes abnormally
high discharge temperatures that are then capable
of degrading the lubricating properties of the oil.
The risk of acid formation is also increased by air
and moisture, and this condition can also lead
to copper plating. All these phenomena may
cause both mechanical and electrical compressor
failures. The typical method for avoiding such
problems is a vacuum pump-down executed
with a vacuum pump, thus creating a minimum
vacuum of 500 microns (0.67 mbar).
NOTICE
The evacuation procedure is based
upon achieving an actual system Vacuum standard
and is NOT TIME DEPENDENT!
Evacuate the installation down to 0,67 mbar to
ensure quality vacuum.
It is recommended to evacuate on both high and
low pressure side to achieve fast and uniform
vacuum in the entire refrigeration system.
When the vacuum level has been reached, the
system must be isolated from the pump.
A vacuum of 0.67mbar has to be reached and
maintained for 4 hours. This pressure is to be
measured in the refrigeration system, and not at
the vacuum pump gauge.
If pressure increases rapidly, the system is not
airtight. Locate and repair leaks. Restart the
vacuum procedure.
If pressure increases slowly, the system contains
moisture inside. Break the vacuum with nitrogen
gas and restart the vacuum process again.
CAUTION
Do not use a megohmmeter nor
apply power to the compressor while it is under
vacuum as this may cause internal damage.
CAUTION
Leak detection must be carried
out using a mixture of nitrogen and refrigerant or
nitrogen and helium. Never use other gasses such
as oxygen, dry air or acetylene as these may form
an inflammable mixture. Pressurize the system on
HP side first then LP side.
5.2 Evacuation
27
FRCC.PC.044.A6.02
Application Guidelines
