8
9
Dehumidifier
6) No ignition sources
No person carrying out work in relation to a refrigeration system which involves exposing any
pipe work that contains or has contained flammable refrigerant shall use any sources of ignition
in such a manner that it may lead to the risk of fire or explosion. All possible ignition sources,
including cigarettesmoking, should be kept sufficiently far away from the site of installation,
repairing, removing and disposal, during which flammable refrigerant can possibly be released
to the surrounding space. Prior to work taking place, the area around the equipment is to be
surveyed to make sure that there are no flammable hazards or ignition risks. No Smoking signs
shall be displayed.
7) Ventilated area
Ensure that the area is in the open or that it is adequately ventilated 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 disperse any released refrigerant and
preferably expel it externally into the atmosphere.
8) 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 flammable refrigerants:
• 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 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.
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, an adequate
temporary solution shall be used. This shall bereported 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;
• Grounding is continuous.
7. 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 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. Intrinsically safe components do not have to be isolated prior to working on them.
8. 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.
9. 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.
10. 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.
11. Leak detection methods
The following leak detection methods are deemed acceptable for systems containing
flammablerefrigerants. 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 used. Leak detection equipment shall be set at a percentage of
the LFL of the refrigerantand 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/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.
