Fujitsu ASTG12CMCB Installation Manual page 2

2-2 Work
• Prior to beginning work on systems containing fl ammable refrigerants, safety checks
are necessary to ensure that the risk of ignition is minimised. For repair to the refrig-
erating system, the precautions in 2-2 to 2-8 shall be complied with prior to conduct-
ing work on the system.
• Work shall be undertaken under a controlled procedure so as to minimize the risk of
a fl ammable gas or vapour being present while the work is being performed.
• All maintenance staff and others working in the local area shall be instructed on the
nature of work being carried out.
• Work in confi ned spaces shall be avoided.
• The area around the workspace shall be sectioned off.
• Ensure that the conditions within the area have been made safe by control of fl am-
mable material.
2-3 Checking for presence of refrigerant
• The area shall be checked with an appropriate refrigerant detector prior to and during
work, to ensure the technician is aware of potentially fl ammable atmospheres.
• Ensure that the leak detection equipment being used is suitable for use with fl am-
mable refrigerants, i.e. nonsparking, adequately sealed or intrinsically safe.
2-4 Presence of fi re extinguisher
• If any hot work is to be conducted on the refrigeration equipment or any associated
parts, appropriate fi re extinguishing equipment shall be available at hand.
• Have a dry powder or CO fi re extinguisher adjacent to the charging area.
2
2-5 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 fl ammable refrigerant shall
use any sources of ignition in such a manner that it may lead to the risk of fi re or
explosion.
• All possible ignition sources, including cigarette smoking, should be kept suffi ciently
far away from the site of installation, repairing, removing and disposal, during which
fl ammable 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 fl ammable hazards or ignition risks. "No Smoking" signs shall
be displayed.
2-6 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.
2-7 Checks to the refrigeration equipment
• Where electrical components are being changed, they shall be fi t for the purpose
and to the correct specifi cation.
• 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 fl ammable 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 compo-
nents, unless the components are constructed of materials which are inherently
resistant to being corroded or are suitably protected against being so corroded.
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.
En-2
CAUTION
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 specifi 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 fl ammable atmospheres.
• Replacement parts shall be in accordance with the manufacturer's specifi 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 specifi 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 confi 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.
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.
CAUTION