CAUTION
Prior to beginning work on systems containing flammable refrigerants, safety checks are necessary to ensure
that the risk of ignition is minimised. For repair to the refrigerating system, the following precautions shall be
complied with prior to conducting work on the system.
the charge size 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 circuits shall be checked for the presence of
refrigerant; marking to the equipment continues to be visible and legible.
marking 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.
7. INFORMATION SERVICING
7.9 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, and 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 possibility 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.
7.10 REPAIRS TO SEALED COMPONENTS
10.1 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.
10.2 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 affected.This shall include damage to
cables, excessive number of connections, terminals not made to original specification, damage to seals,
incorrect fitting 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 flammable atmospheres. Replacement parts shall be in accordance with the
manufacturer s specifications.
NOTE: The use of silicon sealant may inhibit the effectiveness of some types of leak detection equipment.
Instrinsically safe components do not have to be isolated prior to working on them.
7.11 REPAI 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. Intrinscially 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.
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7.12 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.
7. INFORMATION SERVICING
7.13 DETECTION OF FLAMMABLE 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.
7.14 LEAK DETECTION METHODS
The following leak detection methods are deemed acceptable for systems containing flammable refrigerants.
Electronic leak detectors shall be used to detect flammable 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. 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. 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 or
extinguished. If a leakage of refrigernat 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.
7.15 REMOVAL AND EVACUATION
When breaking into the refrigerant circuit to make repairs of 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.
The refrigerant charge shall be recovered into the correct recovery cylinders. 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 this task.
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. This process
shall be repeated until no refrigerant is within the system.
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 closed to any ignition sources and there is ventilation available.
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