Daikin VRV Plus Series General Information Manual page 124

Si33-003.book Page 120 Monday, June 25, 2001 9:06 AM
Appendix
7.9.6 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
Expansion (m) = Full length × Coefficient of thermal expansion × Rise in temperature
For Your Reference
Coefficient of thermal expansion for copper: 16.5 × 10
Example For a pipe length of 10 m and a rise in temperature of 50˚C, expansion reaches 8.2 mm.
120
Take thermal expansion and contraction along the spline into consideration when installing pipe
supports.
-6
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SiE33-003
General Information