14
should be used.
Leak detection method:
For systems with refrigerant R290, electronic
leak detection instrument is available to detect
and leak detection should not be conducted
in environment with refrigerant. Make sure
the leak detector will not become a potential
source of ignition, and is applicable to the
measured refrigerant. Leak detector shall be
set for the minimum ignitable fuel concentra-
tion (percentage) of the refrigerant. Calibrate
and adjust to proper gas concentration (no
more than 25%) with the used refrigerant.
The fluid used in leak detection is applicable
to most refrigerants. But do not use chloride
solvents to prevent the reaction between
chlorine and refrigerants and the corrosion of
copper pipeline.
If you suspect a leak, then remove all the fire
from the scene or put out the fire.
If the location of the leak needs to be welded,
then all refrigerants need to be recovered, or,
isolate all refrigerants away from the leak site
(using cut-off valve). Before and during the
welding, use OFN to purify the entire system.
Removal and Vacuum Pumping
1. Make sure there is no ignited fire source
near the outlet of the vacuum pump and
the ventilation is well.
2. Allow the maintenance and other opera-
tions of the refrigeration circuit should be
carried out according to the general pro-
cedure, but the following best operations
that the flammability is already taken into
consideration are the key. You should fol-
low the following procedures:
• Remove the refrigerant.
• Decontaminate the pipeline by inert gases.
• Evacuation.
• Decontaminate the pipeline by inert gases
again.
• Cut or weld the pipeline.
3. The refrigerant should be returned to the
appropriate storage tank. The system
should be blown with oxygen free nitrogen
to ensure safety. This process may need to
be repeated for several times. This opera-
tion shall not be carried out using com-
pressed air or oxygen
Through blowing process, the system is
charged into the anaerobic nitrogen to reach
the working pressure under the vacuum state,
then the oxygen free nitrogen is emitted
to the atmosphere, and in the end, vacuumize
the system. Repeat this process until all
refrigerants in the system is cleared. After the
final charging of the anaerobic nitrogen,
discharge the gas into the atmosphere pres-
sure, and then the system can be welded.
This operation is necessary for welding the
pipeline.
Procedures of Charging Refrigerants
As a supplement to the general procedure, the
following requirements need to be added:
• Make sure that there is no contamination
among different refrigerants when using a
refrigerant charging device. The pipeline
for charging refrigerants should be as short
as possible to reduce the residual of refrig-
erants in it.
• Storage tanks should remain vertically up.
• Make sure the grounding solutions are
already taken before the refrigeration sys-
tem is charged with refrigerants.
• After finishing the charging (or when it is
not yet finished), label the mark on the
system.
• Be careful not to overcharge refrigerants
Scrap and Recovery
Scrap:
Before this procedure, the technical personnel
shall be thoroughly familiar with the equipment
and all its features, and make a recommended
practice for refrigerant safe recovery. For recy-
cling the refrigerant, shall analyze the refriger-
ant and oil samples before operation. Ensure
the required power before the test.
1. Be familiar with the equipment and opera-
tion.
2. Disconnect power supply.
3. Before carrying out this process, you have
to make sure:
• If necessary, mechanical equipment opera-
tion should facilitate the operation of the
refrigerant tank.
• All personal protective equipment is effec-
tive and can be used correctly.
• The whole recovery process should be car-
ried out under the guidance of qualified
personnel.
• The recovering of equipment and stor-
age tank should comply with the relevant
national standards.
4. If possible, the refrigerating system should
be vacuumized.
5. If the vacuum state can't be reached, you
should extract the refrigerant in each part
of the system from many places.
6. Before the start of the recovery, you should
ensure that the capacity of the storage
