09/2019
- 12 -
Copyright © 2019, Fast ČR, a.s.
Prior to starting work, the area around the appliance must be checked to ensure that
there are no fire hazards or ignition risks present. A "smoking forbidden" sign must
be installed.
1.7 Ventilated area
It must be ensured that the area is ventilated or appropriately ventilated prior to
penetrating the system or performing any work under heat. The intensity of ventilation
must continue for the time that works are performed. Ventilation should safely dissipate
any released refrigerant and draw it out into the atmosphere as a priority.
1.8 Cooling system checks
In places where electrical components are replaced, these components must be suitable
for this purpose and conform to correct specifications. The manufacturer's instructions
for maintenance and service must always be followed. If any doubts arise, it is necessary
to request help from the manufacturer's technical department.
On installations containing flammable refrigerants, it is necessary to perform the
following checks:
– the amount of refrigerant corresponds to the size of the room in which components
containing refrigerant are installed;
– ventilation systems and outlets are in full working order and are not clogged;
– if any indirect cooling circuit is used, the second circuit must be checked for the
presence of refrigerant;
– the markings on the appliance must remain constantly visible and legible, and marking
and signs that are illegible must be repaired;
– The cooling pipes and components are installed in locations where it is not probable
that they will be exposed to any substances that could corrode the parts containing
refrigerant, unless these components are built using materials that are inherently
resistant to corrosion or are appropriately protected against corrosion.
1.9 Electrical device check
The repair and maintenance of electrical components must include safety checks and
inspections of components.
In the event of a malfunction that could affect safety, no electrical power may be
connected to the circuit until the malfunction is satisfactorily resolved. In the event
that the malfunction cannot be immediately repaired but it is necessary to continue
running the appliance, an appropriate temporary solution must be used. The owner of
the appliance must be informed in such a way that all parties know about it.
The initial safety check must ensure:
– that capacitors are discharged: this must be performed in a safe way to prevent the
possibility of sparking;
– that no electrical components or wiring is uncovered during the process of filling,
draining or cleaning the system;
– that the grounding is not interrupted.
2. Repair of sealed components
When repairing sealed components, all the electrical power supply must be disconnected
from the appliance on which work is being performed before sealed lids, etc. are removed.
When it is absolutely necessary to have live power supply going into the appliance while
servicing the appliance, it is necessary to install a permanent device in the most critical
point to detect leakage so that a dangerous situation is averted.
Special attention must be paid to ensuring that as a result of the work performed on
electrical components the cover is not changed to the extent of affecting the level of
protection. This must also include damage to cables, excessive number of connections
and terminals not performed according to original specifications, damaged gaskets,
incorrect configuration of plugs, etc.
It is necessary to ensure that the appliance is mounted safely.
It is necessary to ensure that gaskets or sealing materials are not damaged in such a way
that they no longer serve to prevent the entry of a flammable atmosphere. Spare parts
must conform to the manufacturer's specifications.
Note:
The use of silicone gaskets and seals may suppress the efficiency of certain
type of leak detection devices. Intrinsically safe components do not need to
be disconnected prior to being worked on.
3. Repairs of intrinsically safe components
No permanently inductive or capacitative load may be placed on the circuit without it
being ensured that thereby the permitted voltage and current for the used appliance
is not exceeded.
Intrinsically safe components are the only type on which it is possible to work in
a flammable environment even while under live current. Testing equipment must have
correct specifications.
Parts are replaced using only parts specified by the manufacturer. Different parts could
result in ignition of refrigerant upon leakage into the environment.
4. Cabling
Check that cabling is not exposed to wear and tear, corrosion, excessive pressure,
vibrations, sharp edges or any other negative environmental effects. This check must
also take into consideration the effects of ageing and permanent vibrations from sources
such as compressors or fans.
5. Detection of flammable refrigerants
Under no circumstances may potential sources of ignition be used for locating or
detecting refrigerant leaks.
A halogen burner (or any other type of detector utilising an open flame) must not be used.
6. Leak detection methods
The following leak detection methods are considered acceptable for systems containing
flammable refrigerants.
For the detection of flammable refrigerants, electronic leak detectors must be used,
however their sensitivity may not be appropriate or they may require recalibration.
(Detection equipment must be calibrated in an area without any refrigerant present).
It is important to ensure that the detector is not a potential ignition source and that
it is suitable for the used refrigerant. The leak detector must be set to a percentage of
LFL refrigerant and must be calibrated for the used refrigerant and the respective gas
percentage is confirmed (maximum 25 %).
Leak detection liquids are suitable for use on most refrigerants, however, detergents
containing chlorine must be excluded since chlorine may react with the refrigerant
and corrode copper pipes.
In the event of a suspected leak, all open flames must be removed/extinguished.
In the event that the refrigerant leak is found and requires hard soldering, then all the
refrigerant must be drained from the system or separated (by closing a valve) in a part of
the system distant from the leak. The system must then be cleaned out using oxygen-free
nitrogen (OFN) both before as well as after the hard soldering process.
7. Collection and pump discharge
In the event that the cooling circuit is breached due to repairs – or for any other reason –
conventional procedures must be followed. It is, however, important to adhere to the
best method due to flammability. It is necessary to adhere to the following procedure:
– remove the refrigerant;
– clean out the circuit using inert gas;
– pump out;
– again clean out using inert gas;
– open the circuit by cutting or hard soldering.
The contents of the circuit must be collected into correct collection cylinders. The system
must be "flooded" with OFN (oxygen-free nitrogen) for the unit to remain safe. It may
be necessary to repeat the procedure several times. For this task, neither compressed
air nor oxygen may be used.
Flooding may be achieved by disrupting the vacuum in the system with the use of
OFN, and by continued filling until the operating pressure is achieved, then venting
into the atmosphere and finally lowering to a vacuum. This process must be repeated
if refrigerant still remains in the system. When the last OFN cartridge is used, the system
must be ventilated to atmospheric pressure to enable work to be performed. This activity
is absolutely necessary if hard soldering is to be performed on the pipes.
It is necessary to ensure that the vacuum pump outlets are not nearby to any ignition
source, and ventilation must be provided.
8. Filling procedure
Apart from conventional filling procedures, also the following requirements must be
adhered to.
– It is necessary to ensure that no contamination by various refrigerants occurs when
the filling device is used. Hoses or pipes must be as short as possible to minimise the
amount of refrigerant contained inside of them.
– Cylinders must be held vertically.
– It is important to ensure that the cooling system is grounded prior to being filled with
refrigerant.
– When filling is complete, the system must be marked with a label (if it does not have
one already).
– It is necessary to pay extreme care to ensure that the cooling system is not overfilled.
A pressure test using OFN must be performed before refilling the system. In the case
of a leak, the system must be tested after being refilled but also before being put into
operation. A verification test must be performed before leaving the installation location.
9. Taking out of operation
Prior to performing this procedure it is essential that the technician fully acquaints
him/herself with the device and all its particulars. Correct practice of safely collecting
all refrigerant is recommended. Prior to performing this activity, oil and refrigerant
samples must be taken if an analysis is required prior to using the using the regenerated
refrigerant for the first time. It is essential that prior to starting this activity that electricity
is available.
a) Acquainting one's self with the device and its activity.
b) Electrical disconnection of the system.
c) Prior to starting the procedure, ensure that:
– if required, mechanical device for handling the cylinder with refrigerant is available;
– all personal protective devices are available and used correctly;
– the collection process is constantly under the supervision of a competent person;
– the collection device and cylinders comply with respective norms.
d) Pump out the cooling system if possible.
e) If achieving vacuum is not possible, collection pipes are created to enable the
collection of refrigerant from various parts of the system.
f) Ensure that the cylinder is placed on the scale before the collection of refrigerant is
started.
g) The collection device is turned on and runs according to the manufacturer's instructions.
h) Cylinders are not overfilled. (No more than 80% of liquid content capacity).
i) The maximum operating pressure of the cylinder is not exceeded, even temporarily.
j) When the cylinders are properly filled up and the procedure is complete, ensure that
the cylinders and devices are immediately removed from the installation location and
that all the separation valves on the device are closed.
k) The collected refrigerant must not be filled into a different cooling system until it is
cleaned and checked.
10. Marking with a label
The appliance must be marked with a label indicating that it has been put out of
operation and is without refrigerant. The label must be dated and signed. It is ensured
that there are labels on the appliance indicating that it contains flammable refrigerant.
11. Collection
When the refrigerant is collected from the system, either due to servicing or when
it is put out of operation, it is recommended to adhere to proper practice and safely
collect all the refrigerant.
When the refrigerant is transferred into the cylinders, it is necessary to ensure that
appropriate cylinders for collecting refrigerant are used.
It is necessary to ensure that there is a sufficient number of cylinders available to contain
the complete contents of the system. All the cylinders that are to be used must be
intended for collecting refrigerant and be marked with a label for this refrigerant (i.e.
special cylinders for collecting refrigerant). The cylinders must be complete with a safety
valve and associated closing valves in good working condition. The empty collection
cylinders are pumped empty and if possible cooled prior to collecting refrigerant.
The collection device must be in good operating condition with a set of manuals relating
to the device, which are on hand and it must be suitable for collecting flammable
refrigerants. Apart from this, a set of calibrated scales in good operating condition must
