Heating the pipes, one should take into consideration the coefficient of linear expansion of the product. In the plastic materials, it is higher than the one of metal materials.
For systems in the walls, these values should not be considered, as expansion is absorbed by the product self. In the graphic example, different kinds of material for pipes and fittings have been taken into consideration.
The same temperature and piping length has been considered, to compare the different linear elongation.
The linear expansion can be calculated also through the following formula; Dl = α * L * ∆t
Meaning: Dl = linear elongation in (mm)
α = coefficient of linear elongation
Pipes (mean value) = 0.15 mm/mK
Pipe Fiber and pipe with metal shell (mean value) = 0.05 mm/mK
L = pipe length in m
∆t= difference of temperature between warm water and room temperature.
Example no.1: linear expansion calculation
Data: α = 0.15 mm/mk
L = 6 m
∆ t = 40°C
Calculation: α * L * ∆ t = Dl
0.15 * 6 * 40 = 36 mm
To avoid the linear movements of the brackets for the PP-R pipes in free laying and in case it is necessary, SupraTherm suggests to use the zinc-plated steel shells, available for all the diameters of pipes produced and sold. This accessory reduces the PP-R expansion and prevents the formation of bad bending on the piping, above all in case of warm fluids conveyance and/or where temperatures affect the pipe bending (for ex. industrial buildings, shafts, thermal power station).
1) Refer to the table “Clamping with support bracket for pipes, with metal shell”.
2) Fix the support bracket of the pipe (with rubber protection for warm fluid).
3) Instal the pipes on the support brackets.
4) Put the shell on, taking care that length is in coincidence with both the support points and, if necessary, cover with insulating sheath according to law.