Hitachi AirCore 700 Installation & Maintenance Manual page 10

1. Safety Summary
connected to the circuit until it is satisfactorily dealt with. If the fault cannot be corrected immediately
but it is necessary to continue operation, an adequate temporary solution shall be used. This shall be
reported to the owner of the equipment so all parties are advised. Initial safety checks shall include:
○ that capacitors are discharged: this shall be done in a safe manner to avoid possibility of sparking;
○ that no live electrical components and wiring are exposed while charging, recovering or purging the
system;
○ that there is continuity of earth bonding.
•
Sealed electrical components shall not be repaired.
•
Check that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges or
any other adverse environmental effects. The check shall also take into account the effects of aging or
continual vibration from sources such as compressors or fans.
•
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.
•
Air-tightness test shall be carried out as guaranteed. Charging oxygen, acetylene or other flammable
and toxic gases during leakage inspection and air-tightness test may lead to explosions. It
recommended to use nitrogen gas for this test.
•
The following leak detection methods are deemed acceptable for all refrigerant systems.
○ Electronic leak detectors may be used to detect refrigerant leaks but, in the case of flammable
refrigerants, the sensitivity can be inadequate, or can 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 equipment 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 (no more than 25 %) is confirmed.
○ 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 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 in a part of the system remote from the leak. Removal of refrigerant shall
be according to this manual.
•
When breaking into the refrigerant circuit to make repairs – or for any other purpose – conventional
procedures shall be used. However, for flammable refrigerants it is important that best practice is
followed since flammability is a consideration. The following procedure shall be adhered to:
○ safely remove refrigerant following local and national regulations;
○ evacuate;
○ purge the circuit with inert gas;
○ continuously flush with inert gas when using flame to open circuit;
○ open the circuit.
•
The refrigerant charge shall be recovered into the correct recovery cylinders.
•
The inert gases that can be used are specified. Compressed air or oxygen shall not be used for purging
refrigerant systems.
•
Purging of the refrigerant circuit shall be achieved by breaking the vacuum in the system with inert gas
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. The
system shall be vented down to atmospheric pressure to enable work to take place.
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