EPD 50 | EPD 70
EN
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to cables, excessive number of connections, terminals not made to original specification, damage to
seals, incorrect fitting of glands, etc. Ensure that apparatus is mounted securely. Ensure that seals or
sealing materials have not degraded such that they no longer serve the purpose of preventing the
ingress of flammable atmospheres. Replacement parts shall be in accordance with the manufacturer’s
specifications. NOTE: The use of silicon sealant may inhibit the effectiveness of some types of leak de-
tection equipment. Intrinsically safe components do not have to be isolated prior to working on them.
3. 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 com-
ponents 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.
4. 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 ccount the effects of aging or continual
vibration from sources such as compressors or fans.
5. 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.
6. LEAK DETECTION METHODS
The following leak detection methods are deemed acceptable for systems containing flammable refrige-
rants.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/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.
7. REMOVAL AND EVACUATION
When breaking into the refrigerant circuit to make repairs – or for any other purpose – conventional pro-
cedures shall be used. However, it is important that best practice is followed since flammability is a consi-
deration. Thefollowing 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
