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6) Replacement Copper Tubing [R290]
The copper tubes currently in use are suitable for R290. But do not use them if oily
inside. The residual oil in copper tubes should be as little as possible. (Low residual oil
type copper tubes are used in the shipped units.)
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.
