23
Installation and Maintenance
that the work is carried out. The ventilation should safely disperse
any released refrigerant and preferably expel it externally into the
atmosphere.
●Checks to the refrigeration equipment
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 followed. If in doubt, consult the manufacturer’s technical
department for assistance.
The following checks shall be applied to installations using
ammable 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 being so corroded.
●Checks to electrical devices
Repair and maintenance to electrical components shall include
initial 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
continue 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:
1.That capacitors are discharged: this shall be done in a safe
manner to avoid possibility of sparking;
2.That no live electrical components and wiring are exposed while
charging, recovering or purging the system;
3.That there is continuity of earth bonding.
●Repairs to sealed components
1. 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.
2. 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 aected.This shall include
damage to cables, excessive number of connections, terminals not
made to original specication, damage to seals, incorrect tting 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
ingress of flammable atmospheres.
Replacement parts shall be in accordance with the manufacturer’s
specications.
NOTE : The use of silicon sealant can inhibit the effectiveness of some
types of leak detection equipment. Intrinsically safe components do not
have to be isolated prior to working on them.
●Repair to intrinsically safe components
Do not apply any permanent inductive or capacitance loads to the
circuit without ensuring that this will not exceed the permissible
voltage and current permitted for the equipment in use.
Intrinsically safe components are the only types that can be
worked on while live in the presence of a flammable atmosphere.
The test apparatus shall be at the correct rating.
Replace components only with parts specified by the
manufacturer. Other parts may result in the ignition of refrigerant
in the atmosphere from a leak.
●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.
●Detection of ammable refrigerants
Under no circumstances shall potential sources of ignition be used
in the searching for or detection of refrigerant leaks. A halide torch
(or any other detector using a naked flame) shall not be used.
●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
employed, and the appropriate percentage of gas (25 %
maximum) is conrmed.
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/
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 o 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
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, for flammable refrigerants it is important that best
practice is followed since flammability is a consideration. The
following procedure shall be adhered to:
1.remove refrigerant;
2.purge the circuit with inert gas; evacuate;
3.purge again with inert gas;
4.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
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