Page 39 - +GF+ PPR Aquasystem Catalogue 2017_Neat
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Thermal Expansion & Contraction
Thermoplastics are subject to greater thermal expansion and contraction than metals.
Pipes installed above ground, against walls or in ducts, especially those exposed to temperature
variations, require changes in length to be absorbed in order to prevent strain on the pipes.
Length changes can be absorbed by:
a) Flexible sections
b) Compensators
Flexible sections are the most common solution, being the simplest and the most economical.
Calculation of the positioning of flexible section are therefore described in detail.
Calculation of change in length
During the design and installation of plastic pipes, it is very important to calculate the expansion caused
by the possible difference between operating temperature and installation temperature.
The change in length is calculated with the following formula:
Where:
L = change in length (mm)
L = initial pipe length (m)
T = temperature difference (°C)
α = expansion coefficient (mm/m°C)
The expansion Coefficient
α indicates the elongation of a 1m pipe under a temperature increase of 1°C
Medium thermal expansion coefficient for PP-R pipelines :
Example
Changes in length for PP-R pipe:
L=5m
T=50°C
α = 0.15mm/m°C technical features
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