Zephir ZRP9000CB Manual page 28

Intrinsically safe components are the only types that can be worked on while live in the presence of a flammable
atmosphere. The test apparatus shall be at the correct rating. Replace components only with parts specified by the
manufacturer. Other parts may result in the ignition of refrigerant in the atmosphere from a leak.
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.
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.
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
recalibration. (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.
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 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 pipework are to take place.
Ensure that the outlet for the vacuum pump is not close to any ignition sources and there is ventilation available.
Charging procedures
In addition to conventional charging procedures, the following requirements shall be followed.