17/19
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.
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. REMOVAL AND EVACUATION
When breaking into the refrigerant circuit to make repairs – or for any other purpose –
conventional procedures shall be used. However, for
flammable refrigerants
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. For
appliances containing
flammable refrigerants
the system shall be purged with
oxygen-free nitrogen to render the appliance safe for
flammable refrigerants
. This
process may need to be repeated several times. Compressed air or oxygen shall not be
used for purging refrigerant systems.
For appliances containing
flammable refrigerants
,
refrigerants
purging shall be
achieved by breaking the vacuum in the system with oxygen-free nitrogen 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 oxygen-free nitrogen 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 that
ventilation is 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
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).
•
Extreme care shall be taken not to overfill the
refrigerating system
.
Prior to recharging the system, it shall be pressure-tested with the appropriate purging
gas. 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.
16. DECOMMISSIONING
