Hitachi RAS-18FSXNS2E - Vacuuming

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PMML0628 rev.0 - 05/2023
3
VACUUMING
PIPING WORK AND REFRIGERANT CHARGE
! DANGER
Be sure to use Nitrogen Gas for air-ght test. If other gases such as oxygen gas, acetylene gas or
uorocarbon gas are accidentally used, it may cause an explosion or gas intoxicaon.
3.5.3 Insulaon work
1 Securely insulate high/low pressure and low pressure (for heat recovery system only) gas piping
side and liquid piping side individually. Make sure to insulate the union are nut for the piping
connecon as well.
2 Mount the piping cover equipped with the outdoor unit aer connecng the pipe. Completely
seal the penetraon part at the boom of the pipes with insulaon in order to prevent rain
water from entering the conduit.
3 Cover the gap between the piping cover and pipes with a packing (eld-supplied) aer the
insulaon work is completed.
 NOTE
If the gap is not covered, the unit may be damaged if snow, rain water or animals enter the unit.
3.6 Vacuuming
Connect a manifold gauge and vacuum pump to the check joints.
Heat pump system
High/low pressure gas stop valve
Liquid stop valve
Heat recovery system
High/low pressure gas stop valve
Low pressure gas stop valve
Liquid stop valve
3.6.1 Basic Method
If the penetraon of moisture is suspected, perform “Triple Evacuaon Method” that is described
in the next paragraph.
1 Vacuum unl the pressure reaches 500 microns (0.5 mmHg) or Lower for two hours.
2 Aer vacuum pumping work, stop the vacuum pumping and leave the gauge for one hour.
3 Check to ensure that the pressure in the vacuum gauge does not increase.
4 Tighten the caps of check joint according to the specied torque aer the vacuum drying work.
5 If the pressure inside the gauge does not reach 500 microns, it is considered that there is gas
leakage.
6 Check for any gas leakage once again.
7 If no leakage exists, it might be moisture remains inside the pipes. Perform “Triple Evacuaon
Method”.