Pro-Elec PEL01201 - Removal and evacuation; Charging procedures

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(Detection equipment shall be calibrated in a refrigerant-free area).
• Ensure that the detector is not a potential source of ignition and is suitable for the
refrigerant used. Leak detection equipment shall be set at a percentage of the
LFL of the refrigerant and shall be calibrated to the refrigerant employed and the
appropriate percentage of gas (25%maximum) is conrmed.
• Leak detection uids are suitable for use with most refrigerants but the use of
detergents containing chlorine shall be avoided as the chlorine may react with the
refrigerant and corrode the copper pipe-work.
• If a leak is suspected, all naked ames shall be removed/ extinguished.
• If a leakage of refrigerant is found which requires brazing, all of the refrigerant
shall be recovered from the system, or isolated (by means of shut off valves) in a
part of the system remote from the leak. Oxygen free nitrogen (OFN) shall then be
purged through the system both before and during the brazing process.
Removal and evacuation
• When breaking into the refrigerant circuit to make repairs – or for any other
purpose – conventional procedures shall be used. However, it is important that
best practice is followed since ammability is a consideration. The following
procedure shall be adhered to:
1. Remove refrigerant.
2. Purge the circuit with inert gas.
3. Evacuate.
4. Purge again with inert gas.
5. Open the circuit by cutting or brazing.
• The refrigerant charge shall be recovered into the correct recovery cylinders. The
system shall be “ushed” with OFN to render the unit safe. This process may need
to be repeated several times. Compressed air or oxygen shall not be used for this
task.
• Flushing shall be achieved by breaking the vacuum in the system with OFN
and continuing to ll until the working pressure is achieved, then venting to
atmosphere, and nally pulling down to a vacuum. This process shall be repeated
until no refrigerant is within the system. When the nal OFN charge is used, the
system shall be vented down to atmospheric pressure to enable work to take
place. This operation is absolutely vital if brazing operations on the pipe-work are
to take place.
• Ensure that the outlet for the vacuum pump is not close to any ignition sources and
there is ventilation available.
Charging procedures
• In addition to conventional charging procedures, the following requirements shall
be followed.
1. Ensure that contamination of different refrigerants does not occur when using
charging equipment. Hoses or lines shall be as short as possible to minimise
the amount of refrigerant contained in them.
2. Cylinders shall be kept upright.
3. Ensure that the refrigeration system is earthed prior to charging the system
with refrigerant.
4. Label the system when charging is complete (if not already).
5. Extreme care shall be taken not to overll the refrigeration system.