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7) Evacuation, Vacuum Pump and Refrigerant Charge [R290]
Never allow the oil in the vacuum pump to flow backward. The vacuum level and vacuum
pump may be the same as those for the current refrigerants. However, the rubber hose
and gauge manifold to be used for evacuation and refrigerant charge should be exclusively
for R290.
8) Refrigerant Leak Check
Refrigerant leaks can be detected by charging the unit with a little refrigerant, raising the
pressure with nitrogen and using an electronic detector. Do not use air or oxygen instead
of nitrogen for this purpose, or rise in pressure as well as in temperature may cause R290
to suddenly react with oxygen and explode. Be sure to use nitrogen to prevent explosion.
[b] REFRIGERANT RECOVERY
WARNING
Do not recover the R290 refrigerant in a refrigerant recovery cylinder for
R404A or R134a.
The R290 refrigerant has almost no effect on global warming, so can be released to
outdoors atmosphere without risk to the environment. Recovery should only be considered
if the unit cannot be taken outdoors to evacuate the circuit. If R290 is recovered in a
refrigerant recovery cylinder for R404A or R134a, there is a risk of ignition and a refrigerant
destruction operator may reject collection.
[c] REFRIGERANT REMOVAL
WARNING
Remove the R290 refrigerant from the unit in an area well-ventilated and free
from open flames.
When removing the refrigerant from the unit, be sure the surrounding area is well-ventilated
and free from open flames. Discharge refrigerant in small amounts into the atmosphere. If
the surrounding area is not well-ventilated and exposed to open flames, recover the
refrigerant in a refrigerant recovery cylinder and discharge it in small amounts into the
atmosphere outdoors.
[d] EVACUATION AND RECHARGE
1) Attach charging hoses, service manifold and vacuum pump to the low-side and high-side
(to be fitted by service engineer) access valves.
2) Turn on the vacuum pump.
3) Allow the vacuum pump to pull down to a 760 mmHg vacuum. Evacuating period
depends on the pump capacity.
