Carrier 42QTD007D8S series Installationshandbuch Seite 19

7. INFORMATION SERVICING
7.12 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.
7.13 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.
7.14 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. 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 refrigernat 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.
7.15 REMOVAL AND EVACUATION
When breaking into the refrigerant circuit to make repairs of 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 closed to any ignition sources and there is ventilation available.
GB-18 7