Tesla TT68X71 - Инструкция по эксплуатации - Страница 62

62

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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. 
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. 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. 
Intrinsically safe components do not have to be isolated prior to working on them.

18.   

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.

19. 

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.

20. 

 Detection of flammable refrigerants 

Under no circumstances shall potential sources of ignition be used in the searching for or detection of 
refrigerant leaks. Ahalide torch (or any other detector using a naked flame) shall not be used.

21. 

 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 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. 
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/ 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.

22. 

 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 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. 
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. 
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 close to any ignition sources and there is ventilation 
available.

23. 

 Decommissioning 

Before carrying out this procedure, it is essential that the technician is completely familiar with the equipment