Hisense Hi-Therma Serie Manual De Instalación Y Mantenimiento página 13

GENERAL INFORMATION
- 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.
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
that all parties are advised.
- Initial safety checks shall include:
(1) that capacitors are discharged: this shall be done in a
safe manner to avoid possibility of sparking;
(2) that no live electrical components and wiring are
exposed while charging, recovering or purging the system;
(3) that there is continuity of earth bonding.
Repairs to sealed components
•
- During repairs to sealed components, all electrical
supplies shall be disconnected 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.
- Ensure that by working on electrical components, the
casing is not altered in such a way that the level of
protection is affected, including damage to cables,
excessive number of connections, terminals not made to
original specification, damage to seals, incorrect fitting of
glands, etc.
- Ensure that the apparatus is mounted securely.
- Ensure that seals or sealing materials have not
degraded to the point 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.
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.
- 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
•
- Electronic leak detectors may be used to detect
refrigerant leaks but the sensitivity may not be adequate, or
may need re-calibration for the flammable refrigerants.
- 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 confirmed.
- The use of detergents containing chlorine shall be
avoided.
- 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
•
- The refrigerant charge shall be recovered into the
correct recovery cylinders and 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 purging
refrigerant systems.
- 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.
- The outlet for the vacuum pump is not close to any
ignition sources and that ventilation is available.
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