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English
2 - Safety
n
Replace components only with parts specified by the
manufacturer. Unspecified parts by manufacturer may result
ignition of refrigerant in the atmosphere from a leak.
Cabling
n
Check that cabling will not be subject to wear, corrosion,
excessive pressure, vibration, sharp edges or any other adverse
environmental effects.
n
The check shall also take into account the effects of aging or
continual vibration from sources such as compressors or fans.
Detection of flammable refrigerants
n
Under no circumstances shall potential sources of ignition be
used in the searching or detection of refrigerant leaks.
n
A halide torch (or any other detector using a naked flame) shall
not be used.
Leak detection methods
n
Electronic leak detectors shall be used to detect flammable
refrigerants, but the sensitivity may not be adequate, or may
need recalibration. (Detection equipment shall be calibrated in a
refrigerant-free area.)
n
Ensure that the detector is not a potential source of ignition and is
suitable for the refrigerant used.
n
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 confirmed.
n
Leak detection fluids 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.
n
If a leak is suspected, all naked flames shall be removed/
extinguished.
n
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
n
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
flammability is a consideration. The following procedure shall be
adhered to: • remove refrigerant -> • purge the circuit with inert
gas -> • evacuate -> • purge again with inert gas -> • open
the circuit by cutting or brazing
n
The refrigerant charge shall be recovered into the correct recovery
cylinders.
n
The system shall be “flushed” with OFN to render the unit safe.
n
This process may need to be repeated several times.
n
Compressed air or oxygen shall not be used for this task.
n
Flushing shall be achieved by breaking the vacuum in the system
with OFN and continuing to fill until the working pressure is
achieved, then venting to atmosphere, and finally pulling down to
a vacuum.
n
This process shall be repeated until no refrigerant is present
within the system.
n
When the final OFN charge is used, the system shall be vented
down to atmospheric pressure to enable work to take place.
n
This operation is absolutely vital if brazing operations on the pipe
work are to take place.
n
Ensure that the outlet for the vacuum pump is not close to any
ignition sources and there is ventilation available.
Charging procedures
n
In addition to conventional charging procedures, the following
requirements shall be followed.
- Ensure that contamination of different refrigerants does not
occur when using charging equipment.
- Hoses or lines shall be as short as possible to minimize the
amount of refrigerant contained in them.
- Cylinders shall be kept upright.
- Ensure that the refrigeration system is earthed prior to charging
the system with refrigerant.
- Label the system with the amount charged, when charging is
complete (if not completed prior to charging).
- Extreme care shall be taken not to over fill the refrigeration
system.
n
Prior to recharging the system it shall be pressure tested with OFN
(refer to Leak detection methods section).
n
On completion of charging, but prior to commissioning, the
system shall be leak tested.
n
A follow up leak test shall be carried out prior to leaving the site.
n
Electrostatic charge may accumulate and create a hazardous
condition when charging and discharging the refrigerant. To
avoid fire or explosion, dissipate static electricity during transfer
by grounding and bonding containers and equipment before
charging/discharging.
Decommissioning
n
Before carrying out this procedure, it is essential that the
technician is completely familiar with the equipment and all its
details.
n
It is recommended good practice that all refrigerants are recovered
safely.
