4-Repair to intrinsically safe components
• Do not apply any permanent inductive or capacitance loads to the circuit without
ensuring that this will not exceed the permissible voltage and current permitted for
the equipment in use.
• Intrinsically safe components are the only types that can be worked on while live in
the presence of a ﬂ ammable atmosphere.
• The test apparatus shall be at the correct rating.
• Replace components only with parts speciﬁ ed by the manufacturer.
• Other parts may result in the ignition of refrigerant in the atmosphere from a leak.
• Check that cabling will not be subject to wear, corrosion, excessive pressure, vibra-
tion, 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.
6-Detection of ﬂ ammable 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 ﬂ ame) shall not be used.
7-Leak detection methods
• Electronic leak detectors shall be used to detect ﬂ ammable 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
• 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 conﬁ rmed.
• Leak detection ﬂ uids 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 ﬂ ames 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.
8-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 ﬂ ammability is a consid-
The following procedure shall be adhered to:
• remove refrigerant
• purge the circuit with inert gas
• 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 “ﬂ ushed” 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 ﬁ ll until the working pressure is achieved, then venting to atmosphere,
and ﬁ nally pulling down to a vacuum.
• This process shall be repeated until no refrigerant is within the system.
• When the ﬁ nal 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
• Ensure that the outlet for the vacuum pump is not close to any ignition sources and
there is ventilation available.
• In addition to conventional charging procedures, the following requirements shall be
- Ensure that contamination of different refrigerants does not occur when using
Hoses or lines shall be as short as possible to minimize the amount of refrigerant
contained in them.
- Cylinders shall be kept upright.
- Ensure that the refrigeration system is earthed prior to charging the system with
- Label the system when charging is complete (if not already).
- Extreme care shall be taken not to overﬁ ll the refrigeration system.
• Prior to recharging the system it shall be pressure tested with OFN.
• The system shall be leak tested on completion of charging but prior to commission-
• A follow up leak test shall be carried out prior to leaving the site.