En-3
CAUTION
8-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
fl
ammability is a consid-
eration.
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.
• The system shall be “
fl
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
fi
ll until the working pressure is achieved, then venting to atmosphere,
and
fi
nally pulling down to a vacuum.
• This process shall be repeated until no refrigerant is within the system.
• When the
fi
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.
9-Charging procedures
• 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 when charging is complete (if not already).
- Extreme care shall be taken not to over
fi
ll the refrigeration system.
• Prior to recharging the system it shall be pressure tested with OFN.
• The system shall be leak tested on completion of charging but prior to commission-
ing.
• A follow up leak test shall be carried out prior to leaving the site.
10-Decommissioning
• Before carrying out this procedure, it is essential that the technician is completely
familiar with the equipment and all its details.
• 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 handling refriger-
ant cylinders;
• all personal protective equipment is available and being used correctly;
• the recovery process is supervised at all times by a competent person;
• recovery equipment and cylinders conform to the appropriate standards.
d) Pump down refrigerant system, if possible.
e) If a vacuum is not possible, make a manifold so that refrigerant can be removed
from various parts of the system.
f) Make sure that cylinder is situated on the scales before recovery takes place.
g) Start the recovery machine and operate in accordance with manufacturer’s
instructions.
h) Do not over
fi
ll cylinders. (No more than 80 % volume liquid charge).
i) Do not exceed the maximum working pressure of the cylinder, even temporarily.
j) When the cylinders have been
fi
lled correctly and the process completed, make
sure that the cylinders and the equipment are removed from site promptly and all
isolation valves on the equipment are closed off.
k) Recovered refrigerant shall not be charged into another refrigeration system un-
less it has been cleaned and checked.
11-Labelling
• Equipment shall be labelled stating that it has been de-commissioned and emptied
of refrigerant.
• The label shall be dated and signed.
• Ensure that there are labels on the equipment stating the equipment contains
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am-
mable refrigerant.
CAUTION
2-8 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 con-
nected 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.
- That capacitors are discharged: this shall be done in a safe manner to avoid pos-
sibility of sparking.
- That there no live electrical components and wiring are exposed while charging,
recovering or purging the system.
- That there is continuity of earth bonding.
3-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 servic-
ing, 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 electri-
cal 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 connections, terminals not
made to original speci
fi
cation, damage to seals, incorrect
fi
tting of glands, etc.
• Ensure that apparatus is mounted securely.
• Ensure that seals or sealing materials have not degraded such that they no longer
serve the purpose of preventing the ingress of
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ammable atmospheres.
• Replacement parts shall be in accordance with the manufacturer’s speci
fi
cations.
NOTE: The use of silicon sealant may inhibit the effectiveness of some types of leak
detection equipment.
Intrinsically safe components do not have to be isolated prior to working on
them.
4-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
fl
ammable atmosphere.
• The test apparatus shall be at the correct rating.
• Replace components only with parts speci
fi
ed by the manufacturer.
• Other parts may result in the ignition of refrigerant in the atmosphere from a leak.
5-Cabling
• Check that cabling will not be subject to wear, corrosion, excessive pressure, vibra-
tion, 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.
6-Detection of
fl
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
fl
ame) shall not be used.
7-Leak detection methods
• Electronic leak detectors shall be used to detect
fl
ammable refrigerants, but 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 con
fi
rmed.
• Leak detection
fl
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
fl
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.
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