Daikin VRV System R-22 PLUS Series Manual page 125

Si33-102.book Page 123 Tuesday, June 26, 2001 3:18 PM
SiE33-102
7.8.6 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.
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Starting and stopping the compressor has caused temperature to vary, thus the pipes have expanded and
contracted which places stress on soldered parts.
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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.
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.
General Information
-6
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Appendix
123