07
Do not apply any permanent inductive
or capacitance loads to the circuit with-
out 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 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.
8.Repair to intrinsically safe components
10.Detection of flammable refrigerants
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 equip-
ment 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
11.Leak detection methods
Check that cabling will not be subject
to wear, corrosion, excessive pressure,
vibration, sharp edges or any other
adverse environmental eects. The
check shall also take into account the
eects of aging or continual vibration
from sources such as compressors
or fans.
9.Cabling
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.
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 o 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.
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 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.
12.Removal and evacuation
13.Charging procedures
In addition to conventional charging
procedures, the following requirements
shall be followed. Ensure that
contamination of dierent refrigerants
does not occur when using charging
equipment. Hoses or lines shall be as
short as possible to minimise the
amount of refrigerant contained in them.
Cylinders shall be kept upright.
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