Inhoudsopgave
Advertenties
ENGLISH
•
that no live wiring or electrical components are exposed while loading, recovering, or
purging the system;
•
that there is continuity in the earth connection.
2. Repair of sealed components
•
During the repair of sealed components, all power supplies should be disconnected
from the equipment being worked on prior to any removal of sealed covers, etc. If it is
absolutely necessary to have a power supply to the equipment during service, then a
permanently operating form of leak detection should be placed at the most critical point
to warn of a potentially hazardous situation.
•
Particular attention must be paid to the following to ensure that, when working on
electrical components, the housing is not altered in such a way as to affect safety. This
must include damage to cords, an excessive number of connections, terminals not
conforming to the initial specification, damage to seals, incorrect fitting of the stuffing
box, etc.
•
Ensure that the instrumentation is securely mounted.
•
Ensure that seals or sealing materials have not degraded until no longer being useful
to preventing the penetration of flammable atmospheres. Spare parts must be in
accordance with the manufacturer's specifications.
NOTE: the use of silicone sealant may inhibit the effectiveness of some types of leak-
detection equipment. Intrinsically safe components do not have to be isolated before work.
3. Repair of intrinsically safe components
•
Do not apply any permanent inductive or capacitive load to the circuit without ensuring
that it will not exceed the permissible voltage and current rating for the equipment in
use.
•
Intrinsically safe components are the only type of components that can be worked on
in a flammable atmosphere. The test instrumentation must have the correct assigned
features.
•
Replace components only with parts specified by the manufacturer. Other parts can
ignite the refrigerant in the atmosphere from a leak.
4. Wiring
Verify that the wiring is not subject to wear, corrosion, excessive pressure, vibration, sharp
edges, or any other environmental effects. The verification should also take into account the
effects of ageing or continuous vibration from sources such as compressors or fans.
5. Detection of flammable refrigerants
Under no circumstances should potential ignition sources be used in the search for or
detection of refrigerant leaks. Do not use a halide lamp or any other detector using a naked
flame.
72
FORCECLIMA 9400 SOUNDLESS HEATING
6. Leak-detection methods
•
The following leak-detection methods are considered acceptable for systems containing
flammable refrigerants.
•
Electronic leak detectors should be used to detect flammable refrigerants, but the
sensitivity may not be adequate, or may need recalibration (the detection equipment
should be calibrated in a refrigerant-free area). Ensure that the detector is not a
potential ignition source and that it is suitable for the refrigerant used. The leak-
detection equipment must be set to a percentage of the lower flammability limit of the
refrigerant and calibrated for the refrigerant used with the appropriate percentage of
gas (maximum 25%) confirmed.
•
Leak-detection fluids are suitable for use with most refrigerants, but the use of
detergents containing chlorine must be avoided, as chlorine can react with the
refrigerant and corrode copper pipes.
•
If a leak is suspected, all naked flames must be eliminated/extinguished.
•
If a refrigerant leak is found and requires brazing, all refrigerant must be recovered from
the system, or isolated (by means of shut-off valves) in a part of the system far away
from the leak. Oxygen-free nitrogen must then be purged through the system both
before and during the brazing process.
7. Removal and evacuation
When intervening in the cooling circuit for repairs or any other purpose, conventional
procedures must be followed. However, it is important that best practices are followed, as
flammability is a matter to be taken seriously. The following procedure is to be followed:
1.
Remove the refrigerant.
2.
Purge the circuit with inert gas.
3.
Evacuate.
4.
Purge again with inert gas.
5.
Open the circuit by cutting or brazing.
•
The refrigerant charge must be recovered from the correct recovery cylinders. The
system must be flushed with oxygen-free nitrogen to render the unit safe. This process
may need to be repeated several times. Oxygen or compressed air must not be used for
the task.
•
Cleanliness must be achieved by breaking the vacuum in the system with oxygen-
free nitrogen and continuing to fill until working pressure is reached, then venting to
atmosphere, and finally pushing to a vacuum. This process must be repeated until there
is no refrigerant left in the system. When using the oxygen-free nitrogen end-charge,
the system must be vented to atmospheric pressure to allow for work. This operation is
absolutely vital if brazing operations are to take place on pipes.
•
Ensure that the vacuum pump outlet is not near any source of ignition and that
ventilation is available.
ENGLISH
73
FORCECLIMA 9400 SOUNDLESS HEATING
Advertenties
Inhoudsopgave
