Supra DU100 RESPIRE Manual page 13

PRESENCE OF FIRE EXTINGUISHER
- If any hot work is to be conducted on the refrigeration
equipment or any associated parts, propriate fire
extinguishing equipment shall be available to hand.
Have a dry powder or CO 2 fire extinguisher adjacent
to the charging area.
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 igarette
smoking, 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 equip-ment is to be
surveyed to make sure that there are no flammable
hazards or ignition risks. "No Smoking" signs shall be
displayed.
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 atmo-sphere.
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 as-sistance.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 obstruct-ed; 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: 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.
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 absolute-ly
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.
-Particular attention shall be paid to the following
to ensure that by working on electrical compo-
nents, 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, incor-rect
fitting of glands, etc. Ensure that appara-tus is
mounted securely. Ensure that seals or sealing
materials have not degraded such that they no
longer serve the purpose of prevent-ing 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.
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 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.
LEAK DETECTION METHODS
- The following leak detection methods are
deemed acceptable for systems contain-
ing flammable refrigerants. Electronic leak
detectors shall be used to detect flammable
refrigerants, but the sensitivity may not be
adequate, or may need recalibration. (Detection
equipment shall be calibrated in a refriger-ant-
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 refrig-
erant 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 contain-ing
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.
REMOVAL AND EVACUATION
-When breaking into the refrigerant circuit to
make repairs – or for any other purpose – con-
ventional 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 refriger-
ant; 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 cylin-ders.
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 pipework are to take
place.
-Ensure that the outlet for the vacuum pump is
not close to any ignition sources and there is
ventilation available.
CHARGING PROCEDURES
-In addition to conventional charging proce-dures, the
following requirements shall be followed.
-Ensure that contamination of different refrig-erants
does not occur when using charging equipment.
Hoses or lines shall be as short as possible to
minimise 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 overfill 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 commissioning. A
follow up leak test shall be carried out prior to leaving
the site.