INVENTOR V5MFI32-60, User & Installation Manual

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9. Checks to electrical devices
10. Repairs to sealed components
marking 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.
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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 circuits shall be checked
for the presence of refrigerant; marking to the equipment continues to be visible and
legible.
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, and 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.
10.1 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.
10.2 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.
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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. Instrinsically safe components do not have to be isolated prior to working on them.
11. 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. Intrinscially 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.
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The refrigerant charge shall be recovered into the correct recovery cylinders. 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.
12. 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.
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15. Removal and evacuation
When breaking into the refrigerant circuit to make repairs of for any other purpose
conventional 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 refrigerant;
purge the circuit with inert gas;
evacuate;
purge again with inert gas;
open the circuit by cutting or brazing.
13. 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.
14. Leak detection methods
The following leak detection methods are deemed acceptable for systems containing flammable
refrigerants. 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. 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. 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 or extinguished. If a leakage of refrigernat
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.
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.
Ensure that the outlet for the vacuum pump is not closed to any ignition sources and there
is ventilation available.