Hoshizaki KM-40B, Service Manual

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7) Evacuation, Vacuum Pump and Refrigerant Charge [R134a]
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 R134a.
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 R134a to suddenly react with oxygen and explode. Be sure to use nitrogen to
prevent explosion.
[b] REFRIGERANT RECOVERY
No refrigerant Access Valve is provided in the unit. Install a proper Access Valve on the
low-side line (ex. Compressor Process Pipe). Recover the refrigerant from the Access
Valve, and store it in a proper container. Do not discharge the refrigerant into the
atmosphere.
[c] EVACUATION AND RECHARGE
1) Attach Charging Hoses, a Service Manifold and a Vacuum Pump to the system.
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.
4) Close the Low-side Valve on the Service Manifold.
5) Disconnect the Vacuum Pump, and attach a Refrigerant Charging Cylinder.
Remember to loosen the connection, and purge the air from the Hose. See the
Nameplate for the required refrigerant charge.
6) Open the Low-side Valve. Do not invert the Charging Cylinder. A liquid charge will
damage the Compressor.
7) Turn on the icemaker when charging speed gets slow. Turn off the icemaker when
the Low-side Gauge shows approximately 0 kg/cm
2
. Do not run the icemaker at
vacuum pressures. Close the Low-side Valve when the Charging Cylinder gets
empty.