Aktobis WDH-520EB User Manual - Page 7

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INSTRUCTION FOR REPAIRING APPLIANCES CONTAINING R 290

12.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.

13.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.

14.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 OFNcharge is used, the system shall be vented

down to atmospheric pressure to enable work to takeplace. 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 isventilation available.

15. Charging procedures

In addition to conventional charging procedures, the following requirements shall be

followed.

- Ensure that contamination of different refrigerants does not occur when using

charging equipment. Hoses or lines shall be as short as possible to minimise the