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8
ENGLISH
• Ensure that the area is in the open or that it is adequately venti-
lated before breaking into the system or conducting any hot
work. A degree of ventilation shall continue during the period
that the work is carried out. The ventilation should safely dis-
perse any released refrigerant and preferably expel it externally
into the atmosphere.
Refrigeration equipment Checking
Where electrical components are being changed, they shall be fit
for the purpose and to the correct specification. At all times the
manufacturer’s maintenance and service guidelines shall be fol-
lowed. If in doubt, consult the manufacturer’s technical department
for assistance.
The following checks shall be applied to installations using flam-
mable refrigerants:
• The actual refrigerant charge is in accordance with the room size
within which the refrigerant containing parts are installed;
• The ventilation machinery and outlets are operating adequately
and are not obstructed;
• If an indirect refrigerating circuit is being used, the secondary
circuit shall be checked for the presence of refrigerant;
• Marking to the equipment continues to be visible and legible.
Markings and signs that are illegible shall be corrected;
• Refrigeration pipe or components are installed in a position
where they are unlikely to be exposed to any substance which
may corrode refrigerant containing components, unless the
components are constructed of materials which are inherently
resistant to being corroded or are suitably protected against be-
ing so corroded.
Electrical devices checking
Repair and maintenance to electrical components shall include ini-
tial safety checks and component inspection procedures. If a fault
exists that could compromise safety, then no electrical supply shall
be connected to the circuit until it is satisfactorily dealt with. If the
fault cannot be corrected immediately but it is necessary to contin-
ue operation, an adequate temporary solution shall be used. This
shall be reported to the owner of the equipment so all parties are
advised.
Initial safety checks shall include:
• That capacitors are discharged: this shall be done in a safe man-
ner to avoid possibility of sparking;
• That no live electrical components and wiring are exposed while
charging, recovering or purging the system;
• That there is continuity of earth bonding.
Repairs to sealed components
During repairs to sealed components, all electrical supplies shall
be disconnected from the equipment being worked upon prior to
any removal of sealed covers, etc. If it is absolutely necessary to
have an electrical supply to equipment during servicing, then a
permanently operating form of leak detection shall be located at
the most critical point to warn of a potentially hazardous situation.
Particular attention shall be paid to the following to ensure that by
working on electrical components, the casing is not altered in such
a way that the level of protection is affected.
This shall include damage to cables, excessive number of connec-
tions, terminals not made to original specification, damage to
seals, incorrect fitting of glands, etc.
• Ensure that the apparatus is mounted securely.
• Ensure that seals or sealing materials have not degraded to the
point that they no longer serve the purpose of preventing the in-
gress of flammable atmospheres. Replacement parts shall be in
accordance with the manufacturer’s specifications.
NOTE :
The use of silicon sealant can inhibit the effectiveness of some
types of leak detection equipment. Intrinsically safe compo-
nents do not have to be isolated prior to working on them.
Cabling
Check that cabling will not be subject to wear, corrosion, excessive
pressure, vibration, sharp edges or any other adverse environmental
effects. The check shall also take into account the effects of aging
or continual vibration from sources such as compressors or fans.
Leak detection methods
The following leak detection methods are deemed acceptable for
all refrigerant systems.
Electronic leak detectors may be used to detect refrigerant leaks
but, in the case of flammable refrigerants, the sensitivity may not
be adequate, or may need re-calibration.
(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 em-
ployed, and the appropriate percentage of gas (25 % maximum) is
confirmed.
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.
If a leak is suspected, all naked flames shall be removed/extin-
guished.
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. For appliances containing flammable refrigerants, oxygen free
nitrogen (OFN) shall then be purged through the system both be-
fore 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, for flammable refrigerants it is important that best prac-
tice 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.
The refrigerant charge shall be recovered into the correct recovery
cylinders.
For appliances containing flammable refrigerants, the system shall
be “flushed” 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 purging refrigerant
systems.
For appliances containing flammable refrigerants, flushing shall be
achieved by breaking the vacuum in the system with OFN and
continuing to fill until the working pressure is achieved, then vent-
ing to atmosphere, and finally pulling down to a vacuum.
This process shall be repeated until no refrigerant is within the sys-
tem.
When the final 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 ig-
nition sources and that ventilation is available.
Charging procedures
In addition to conventional charging procedures, the following re-
quirements 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 minimise 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 when charging is complete (if not already).
– Extreme care shall be taken not to overfill the refrigeration sys-
tem.
Prior to recharging the system, it shall be pressure-tested with the
appropriate purging gas.
The system shall be leak-tested on completion of charging but pri-
or to commissioning.
A follow up leak test shall be carried out prior to leaving the site.
Decommissioning
Before carrying out this procedure, it is essential that the techni-
cian is completely familiar with the equipment and all its detail. It is
recommended good practice that all refrigerants are recovered
safely. Prior to the task being carried out, an oil and refrigerant
sample shall be taken in case analysis is required prior to re-use of
reclaimed refrigerant.
It is essential that electrical power is available before the task is
commenced.
a) Become familiar with the equipment and its operation.
b) Isolate system electrically.
c) Before attempting the procedure, ensure that:
• mechanical handling equipment is available, if required, for han-
dling refrigerant cylinders;
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