(The nature and amount of the extraneous material inside the pipe can be checked during
flushing by placing a rag lightly over the end of the pipe. In the unlikely case that even a small
quantity of moisture is found then the inside of the pipe should be dried out thoroughly.)
1. Flush the inside of the pipe with nitrogen gas. (Until such time as the moisture disappears.)
2. Carry out a thorough vacuum drying operation. (See page 39)
a) Refrigerant piping
Selection of piping material
1. Foreign materials inside pipes (including oils for fabrication) must be 30mg/10m or less.
2. Use the following material specification for refrigerant pipping:
3. Make sure to use the particular branches of piping that have been selected referring to
4. The piping minimum thickness and material.
1 Close the main valve on the nitrogen cylinder.
2 Repeat the above operation for unit B.
3 When the liquid pipe operations have been completed then do the same with the gas
• construction material: Phosphoric acid deoxidized seamless copper for refrigerant.
• size: Determine the proper size referring to chapter "Example of connection".
• The wall thickness of the refrigerant piping should comply with relevant local and national
For R-410A the design pressure is 4.0 MPa.(40.8kgf/cm
chapter "Example of connection".
* The min. thickness of the pipes shows the requirements of Japanese High Pressure Gas Control
low. (As of Jan. 2003)
And the temper grade (
The thickness and material should comply with relevant local and national regulations for
the design pressure 4.0MPa (40bar).
Select the wall thickness in accordance with relevant local and national regulations.
, 1/2H) shows the material type of JIS H 3300.
Minimum thickness (mm)