# PVC Pipes - Expansion Loops

## Temperature expansion and contraction in PVC piping systems

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Temperature expansion and contraction in PVC piping systems can be compensated with

- expansion loops consisting of pipes and 90
^{o}elbows - flexible bends
- bellows and rubber expansion joints
- piston type expansion joints

### Expansion Loops

Expansion loops are made of standard pipes and elbows and can be produced on the site and adapted to the actual situation.

The length of leg A can be calculated as

A = 0.72 (D δl)^{1/2}(1)

where

A = length of leg A (ft)

D = nominal outside diameter (inches)

δl = thermal expansion of pipe (inches)

The length of leg B can be calculated as

B = 1.44 (D δl)^{1/2}(2)

where

B = length of leg B (ft)

### Example - Expansion Loop

A *2" *PVC Schedule 40 straight pipe with length *300 ft* is installed at* 75 ^{o}F* and operated at

*120*. The expansion coefficient of PVC is

^{o}F*28 10*.

^{-6}in/in^{o}FThe expansion of the PVC pipe can be calculated as

δl = α L_{o}δt

= (28 10^{-6 }in/in^{ o}F) (300 ft) (12 in/ft) ((120^{o}F) - (75^{o}F))

= 4.5 inches

where

δl = expansion (inch)

L_{o}= length of pipe (inch)

δt = temperature difference (^{o}F)

α = linear expansion coefficient (inch/inch^{o}F)

The length of leg A can be calculated:

A = 0.72 (D δl)^{1/2}=

0.72 [(2.375 in) (4.5 in)]^{1/2}

= 2.4 ft

The length of leg B can be calculated:

B = 1.44 (D δl)^{1/2}=

1.44 [(2.375 in) (4.5 in)]^{1/2}

= 4.7 ft

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