Daikin VRV II Series, Design, Installation & Testing Instructions, Page: 155 / 242

Si39-303 Appendix
General Information 149
7.12.6 Example 6: Cracks develop in field pipes due to thermal expansion
and contraction
Situation
Refrigerant piping has developed cracks in soldered points and is leaking gas.
Cause
Both ends of the pipe have been tightly fixed in place.
↓
Starting and stopping the compressor has caused temperature to vary, thus the pipes have expanded and
contracted which places stress on soldered parts.
↓
Cracks have formed because of repeated expansion and contraction.
Remedial Action
Fit the pipe with a loop as shown in the below drawing.
Main Points
!
Take thermal expansion and contraction along the spline into consideration when installing pipe
supports.
For Your
Reference
Expansion (m) = Full length × Coefficient of thermal expansion × Rise in temperature
Coefficient of thermal expansion for copper: 16.5 × 10
-6
Example For a pipe length of 10 m and a rise in temperature of 50°C, expansion reaches 8.2 mm.