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If the temperature is higher than 30and the humidity
is higher than RH 80, then thickness of the sealing
materials should be at least 20mm in ouder to avoid
condensation on the surface of the sealing.
Be sure to insulate the liquid and gas-side field piping.
NOTICE
Any exposed piping may cause condensation.
(The highest temperature that the gas-side
piping
can reach is around 120°C, so be sure to
use
insulating material which is very resistant.)
DANGER
No not touch piping and internal parts.
7.7. Cautions for necessity of a trap
To avoid the the risk of oil held inside the riser piping flowing
back into the compressor when stopped and causing
liquid compression phenomenon, or cases of deterioration
of oil return, it will be necessary to provide a trap at each
difference in height of 10m in the riser gas piping.
A trap is not necessary when the outdoor unit is
installed at higher position than the indoor unit.
8. Leak test and vacuum
drying
When all piping work is complete and the outdoor unit is
connected to the indoor unit, it is necessary to :
check for any leakages in the refrigerant piping
to perform vacuum drying to remove all moisture in
the refrigerant piping.
If there is a possibility of moisture being present in the
refrigerant piping (for example, rainwater may have
entered the piping), first carry out the vacuum drying
procedure below until all moisture has been removed.
8.1. General guidelines
All piping inside the unit has been factory tested for
leaks.
Use a 2-stage vacuum pump with a non-return
valve which can evacuate to a gauge pressure of-
100.7kPa(5 Torr absolute,-755mm Hg).
Connect the vacuum pump to both the service port
of the gas stop valve and the liquid stop valve to
increase efficiency.
NOTICE
Do not purge the air with refrigerants. Use a
vacuum pump to evacuate the installation. No
additional refrigerant is provided for air purging.
Make sure that the gas stop valve and
liquid
stop valve are firmly closed before
performing
the leak test or vacuum drying.
8.2. Leak test
The leak test must satisfy specification EN378-2.
1. Vacuum leak test
1.1 Evacuate the system from the liquid and gas
piping to -100.7 kPa(5 Torr).
1.2 Once reached, turn off the vacuum pump and
check that the pressure does not rise for at least
1 minute.
1.3 Should the pressure rise, the system may
either contain moisture (refer to the paragraph "
Vacuum drying ") or have leaks.
2. Pressure leak test
2.1 Break the vacuum by pressurizing with nitrogen
gas to a minimum gauge pressure of 0.2 MPa (2
bar). Never set the gauge pressure higher than
the maximum operation pressure of the unit, i.e.
4.0MPa (40bar).
2.2 Test for leaks by applying a bubble test solution
to all piping connections.
NOTICE
Make sure to use a recommended bubble test
solution from your wholesaler.
Do not use soap water, which may cause cracking of
falre nuts (soap water may contain salt, which absorbs
moisture that will freeze when the piping gets cold).
and/or lead to corrosion of flared joints (soap water
may contain ammonia which causes a corrosive effect
between the brass flare nut and the copper flare).
8.3. Vacuum drying
To remove all mositure from the system, proceed as follows:
1. Evacuate the system for at least 2 hours to a target
vacuum of -100.7 kPa(=-1.007 bar).
2.
Check that, with the vacuum pump turned off, the
target vacuum is maintained for at least 1 hour.
3.
Should you fail to reach the target vacuum within 2
hours or maintain the vacuum for 1 hour, the system
may contain too much moisture.
4.
In that case, break the vacuum by pressurizing with
nigrogen gas to a gauge pressure of 0.05 MPa (0.5bar)
and repeat steps 1 to 3 unit all moisture has been
removed.
5.
The stop valves can now be opened, and/or
additional refrigerant can be charged.
