Hitachi RAS-10HRNM, Service Manual, Page: 64 / 482

3.2.5 Refrigerant charge
C A U T I O N
• Do not charge OXYGEN, ACETYLENE, or other flammable and poisonous gases into the refrigerant because
an explosion will occur. It is recommended that oxygen free nitrogen be charged for these types of tests cycle
when performing a leakage test or an airtight test. These types of gases are extremely dangerous.
• Insulate the unions and flare-nuts at the piping connection part completely.
• Insulate the liquid piping completely to avoid a decrease of performance; if not, it will cause sweating on the
surface of the pipe.
• Charge refrigerant correctly. Overcharging or insufficient charging could cause a compressor failure.
• Check for refrigerant leakage in detail. If a large refrigerant leakage occurred, it would cause difficulty with
breathing or harmful gases would occur if a fire were being used in the room.
• If the flare nut is tightened too hard, the flare nut may crack after a long time and cause refrigerant leakage.
3.2.6 Caution of the pressure by check joint
When the pressure is measured, use the check joint of gas stop valve (A), and use the check joint of liquid piping (B) in the
figure below.
At that time, connect the pressure gauge according to the following table because of high pressure side and low pressure
side changes by operation mode.
Cooling operation Heating operation
Check joint for gas stop valve -A- Low pressure High pressure
Check joint for piping -B- High pressure Low pressure
Check joint for liquid stop valve -C- Exclusive for vacuum pump and refrigerant charge
N O T E
Be careful that refrigerant and oil do not splash to the electrical parts at removing the charge hoses.
The below figures show examples of 3 HP and 5 HP:
•
The one on the right is an RAS-5H(V)RNM1E case and the one in the left is an RAS-3HVRNME in case for IVX Series.
• The one on the right is an RAS-5HVRNS1E case and the one in the left is an RAS-3HVRNS in case of ES Series.
3 Piping work and
refrigerant charge
56
SMGB0060 rev. 1- 12/2010