Panasonic CS-CZ25WKE Service Manual page 8

Detection of flammable refrigerants

Under no circumstances shall potential sources of ignition be used in the searching or detection of refrigerant leaks.

A halide torch (or any other detector using a naked flame) shall not be used.

The following leak detection methods are deemed acceptable for all refrigerant systems.
- No leaks shall be detected when using detection equipment with a sensitivity of 5 grams per year of refrigerant or
better under a pressure of at least 0,25 times the maximum allowable pressure (>1.04MPa, max 4.15MPa) for
example, a universal sniffer.
- Electronic leak detectors may 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.)
6.
- 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 also suitable for use with most refrigerants, for example, bubble method and fluorescent
method agents. 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. The precautions in #7 must be
followed to remove the refrigerant.
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 with inert gas ->
• open the circuit by cutting or brazing

The refrigerant charge shall be recovered into the correct recovery cylinders.
7.

The system shall be purged with OFN to render the appliance safe. (remark: OFN = oxygen free nitrogen, type of inert gas)

This process may need to be repeated several times.

Compressed air or oxygen shall not be used for this task.

Purging 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 potential ignition sources and there is ventilation available.
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 minimize the amount of refrigerant contained in them.
- Cylinders shall be kept in an appropriate position according to the instructions.
- Ensure that the refrigerating system is earthed prior to charging the system with refrigerant.
- Label the system when charging is complete (if not already).
8.
- Extreme care shall be taken not to over fill the refrigerating system.

Prior to recharging the system it shall be pressure tested with OFN (refer to #7).

The system shall be leak tested on completion of charging but prior to commissioning.

A follow up leak test shall be carried out prior to leaving the site.

Electrostatic charge may accumulate and create a hazardous condition when charging and discharging the refrigerant.
To avoid fire or explosion, dissipate static electricity during transfer by grounding and bonding containers and equipment
before charging/discharging.
CAUTION
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