Carrier 30KAV-ZE Series Installation, Operation And Maintenance Instructions page 6

1 - SAFETY CONSIDERATONS
Do not remove valves/fusible plugs, even if the fire risk is
under control for a particular installation. There is no
guarantee that the accessories have been re-installed if the
system is changed or for transport with a gas charge.
When the unit is subjected to fire, a safety device prevents
rupture due to over-pressure by releasing the refrigerant.
The fluid may then break down into toxic residues when in
contact with flames:
■ Stay away from the unit;
■ Ensure the personnel in charge of extinguishing the fire
are duly warned and issued with recommendations;
■ Fire extinguishers appropriate to the system and the
refrigerant type must be easily accessible.
NOTE : Pressure equipment for the hydraulic side (optional)
are delivered as separate items. Their integration in the
complete hydraulic installation remain under the user's
responsibility.
All factory-fitted relief valves are lead-sealed to prevent any
calibration change.
The external relief valves must always be connected to drain
pipes for units installed in a closed room. Refer to the
installation regulations, for example those of European
standard EN 378 and EN 13136. These pipes must be installed
in a way that ensures that people and property are not
exposed to refrigerant leaks. As the fluids can be diffused in
the air, ensure that refrigerant is discharged away from
building air intakes or that it is discharged into a sufficient
quantity of suitable absorbent material (note that R1234ze(E)
refrigerant is heavier than air). The valves must be checked
periodically.
If the relief valves are factory-fitted on a changeover valve,
this is equipped with a relief valve on each of the two outlets.
Only one of the two relief valve is in operation, the other one
is isolated. Never leave the changeover valve in the
intermediate position, i.e. with both circuits open (move the
lever fully forwards or backwards depending on the output
to be isolated). If a valve is removed for checking or
replacement, make sure there is still a valve active on each
of the changeover valves installed on the unit.
Provide a drain in the drain pipe, close to each relief valve,
to avoid an accumulation of condensate or rain water.
It is recommended to install an indicating device to check
whether any refrigerant has leaked from the relief 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 nuisance
tripping or leaks, replace or re-calibrate the valve.
6
CHECKING THE PROTECTIVE DEVICE:
■ External overpressure devices (external relief valves) must
be replaced or checked to ensure that their settings and
operation are correct at least every five years or in
accordance with national regulations, at the earliest
opportunity.
■ The high pressure (SRMCR) safety loop must be tested at
least once a year to check it is operating correctly; this
must include the compressor shut-down and its activation
and deactivation values.
The company or organisation that conducts a pressure switch
test must establish and implement detailed procedures for:
- Safety measures,
- Measuring equipment,
- Values and tolerances for cut-off and discharge devices,
- Test stages,
- Recommissioning of the equipment.
The manufacturer recommends contacting Carrier Service
for this type of test. An example of the test procedure without
removing the pressure switch is given in section 10.8.4 of
this manual.
WARNING: If the test results in the replacement of the
pressure switch, it is necessary to recover the refrigerant
charge. These pressure switches are not installed on
Schraeder type automatic valves.
If the machine operates in a corrosive environment, inspect the
protection devices more frequently.
Do not attempt to repair or recondition a valve if there has been
any corrosion or build-up of foreign material (rust, dirt, scale, etc.)
on the valve body or mechanism. In this case, it must be replaced.
Do not install relief valves in series or backwards.