5
The relief valve must only be removed if the fire risk is
fully controlled and after checking that this is allowed by
local regulations and authorities. This is the responsibility
of the operator.
When the unit is subjected to fire, safety devices prevent
rupture due to over-pressure by releasing the refrigerant.
The fluid may then be decomposed into toxic residues
when subjected to the flame:
- Stay away from the unit.
- Set up warnings and recommendations for personnel in
charge to stop the fire.
- Fire extinguishers appropriate to the system and the
refrigerant type must be easily accessible.
The external relief valves must in principle be connected
to discharge pipes for units installed in a room. Refer to
the installation regulations, for example those of European
standards EN 378 and EN 13136.
They include a sizing method and examples for configura-
tion and calculation. Under certain conditions these stan-
dards permit connection of several valves to the same
discharge pipe. Note: Like all other standards these EN
standards are available from national standards organi-
sations.
These pipes must be installed in a way that ensures that
people and property are not exposed to refrigerant leaks.
These fluids may be diffused in the air, but far away from
any building air intake, or they must be discharged in a
quantity that is appropriate for a suitably absorbing
environment.
It is recommended to install an indicating device to show
if part of the refrigerant has leaked from the valve. The
presence of oil at the outlet orifice is a useful indicator
that refrigerant has leaked. Keep this orifice clean to
ensure that any leaks are obvious.
The calibration of a valve that has leaked is generally
lower than its original calibration. The new calibration
may affect the operating range. To avoid a nuisance
tripping or leaks, replace or re-calibrate the valve.
Periodic check of the relief valves: See paragraph 1.3
“Maintenance safety considerations”.
Provide a drain in the discharge circuit, close to each
relief valve, to avoid an accumulation of condensate or
rain water.
All refrigerant handling precautions must comply with
local regulations.
Ensure good ventilation, as accumulation of refrigerant
in an enclosed space can displace oxygen and cause
asphyxiation or explosions.
Inhalation of high concentrations of vapour is harmful
and may cause heart irregularities, unconsciousness, or
death. Vapour is heavier than air and reduces the amount
of oxygen available for breathing. These products cause
eye and skin irritation. Decomposition products are
hazardous.
1.2 - Equipment and components under pressure
These products incorporate equipment or components under
pressure, manufactured by Carrier or other manufacturers.
We recommend that you consult your appropriate national
trade association or the owner of the equipment or compo-
nents under pressure (declaration, re-qualification, retesting,
etc.). The characteristics of this equipment/these components
are given on the nameplate or in the required documenta-
tion, supplied with the products.
The units are intended to be stored and operate in an
environment where the ambient temperature must not be
less than the lowest allowable temperature indicated on
the nameplate.
See section “9.6 - Pressure vessels”.
1.3 - Maintenance safety considerations
Carrier recommends the following drafting for a logbook
(the table below should not be considered as reference
and does not involve Carrier responsibility):
Intervention
Name of the
commissioning
engineer
Applicable
national
regulations
Verification
Organism
Date
Nature
(1)
(1) Maintenance, repairs, regular verifications (EN 378), leakage, etc.
Engineers working on the electric or refrigeration compo-
nents must be authorized, trained and fully qualified to do so.
All refrigerant circuit repairs must be carried out by a trained
person, fully qualified to work on these units. He must have
been trained and be familiar with the equipment and the
installation. All welding operations must be carried out by
qualified specialists.
The insulation must be removed and heat generation must
be limited by using a wet cloth.
Any manipulation (opening or closing) of a shut-off valve
must be carried out by a qualified and authorised engineer.
These procedures must be carried out with the unit shut-
down.
NOTE: The unit must never be left shut down with the
liquid line valve closed, as liquid refrigerant can be trapped
between this valve and the expansion device. (This valve
is situated on the liquid line before the filter drier box.)
During any handling, maintenance and service operations
the engineers working on the unit must be equipped with
safety gloves, glasses, shoes and protective clothing.
Never work on a unit that is still energized.
Never work on any of the electrical components, until the
general power supply to the unit has been cut using the
disconnect switch(es) in the control box(es).
