INVENTOR P8MVI32-09WiFi, Service Manual

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7
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 or 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.
15. 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:
l
remove refrigerant;
l
purge the circuit with inert gas;
l
evacuate;
l
purge again with inert gas;
l
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.
16. Charging procedures
In addition to conventional charging
procedures, the following requirements
shall be followed:
l
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.
l
Cylinders shall be kept upright.
l
Ensure that the refrigeration system is
earthed prior to charging the system with
refrigerant.
l
Label the system when charging is
complete (if not already).
l
Extreme care shall be taken not to
overfill the refrigeration system.