Linear expansion
The linear expansion of pipes bases on the difference between the operating temperature and the installation temperature.
The coefficient (a) of linear expansion of Dacta Therm - Fiberglass Reinforced PP-R pipes is α Dacta Therm - Fiber glass Reinforced PP-R Pipe: 0.035 mm/mK The Dacta Therm - Fiberglass Reinforced PP-R pipes require enough space to expand (see page 7). An expansion control is necessary for straight and long fiberglass pipes (over 120 ft). The Dacta Therm PP-R pipes without the sta- bilizing compound should have expansion control on every 30 ft of straight runs.Risers made of - composite pipes may be installed tightly without expansion compensation. The following for-mula, data tables, calculation examples and diagrams help to determine the linear expansion. The difference between working temperature and maximum or minimum installa-tion temperature is fundamental to calculate the linear ex-pansion. ∆L=LDt* a ∆L=Linear Expansion (mm) L =Pipe Length (m) ∆T=Temperature Difference between Working and Installation temperature (° K, °C or °F) a = Coefficient of Linear Expansion (mm/mK) Example; if a 2m long Dacta Therm - fiberglass re-inforced PP-R pipe operates in 65 °C and is installed in 25° C, the linear expansion will be calculated as follows; ∆L=L*∆t* α ∆L=2*40*0,035 ∆L=2,8 mm
The linear expansion of pipes is based on the difference be- tween the operating temperature and the installation tem- perature:
T = T operating temperature - T installation temperature
For this reason cold water pipes have practically no linear expansion. Due to the heat-dependent expansion of the material, the linear expansion must be given special consideration for hot water and heating installations. There is a difference between the installation types: • Open installation • Installation in ducts • Concealed installations with piping insulated In the case of exposed installation pipes (e.g. in the base- ment), perfect visual characteristics and dimensional sta-bility are significant. Dacta Therm PP-R pipes for hot water and heating systems facilitate this. The coefficient (a) of linear expansion of Dacta Therm PP-R pipes is comparable to the linear expansion of metal pipes: The coefficient of linear expansion of Dacta Therm PP-R standard piping systems without stabilizing compo-nents is α Dacta Therm Standard PP-R Pipe: 0.150 mm/mK
Pipe Length (mt) Difference in temperatures (°C) ΔT = T operating temperature - T installation temperature 10°C 20°C 30°C 40°C 50°C 60°C 70°C 80°C 10°C 20°C 30°C 40°C 50°C 60°C 70°C 80°C 10°C 20°C 30°C 40°C 50°C 60°C 70°C 80°C 1,0 1.50 3.00 4.50 6.00 7.50 9.00 10.50 12.00 0.40 0.70 1.10 1.40 1.80 2.10 2.50 2.80 0.30 0.60 0.90 1.20 1.50 1.80 2.10 2.40 2,0 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 0.70 1.40 2.10 2.80 3.50 4.20 4.90 5.60 0.60 1.20 1.80 2.40 3.00 3.60 4.20 4.80 3,0 4.50 9.00 13.50 18.00 22.50 27.00 21.50 36.00 1.10 2.10 3.20 4.20 5.30 6.30 7.40 8.40 0.90 1.80 2.70 3.60 4.50 5.40 6.30 7.20 4,0 6.00 12.00 18.00 24.00 30.00 36.00 42.00 48.00 1.40 2.80 4.20 5.60 7.00 8.40 9.80 11.20 1.20 2.40 3.60 4.80 6.00 7.20 8.40 9.60 5,0 7.00 15.00 22.50 30.00 37.50 45.00 52.50 60.00 1.80 3.50 5.30 7.00 8.80 10.50 12.30 14.00 1.50 3.00 4.50 6.00 7.50 9.00 10.50 12.00 6,0 9.00 18.00 27.00 36.00 45.00 54.00 63.00 72.00 2.10 4.20 6.30 8.40 10.50 12.60 14.70 16.80 1.80 3.60 5.40 7.20 9.00 10.80 12.60 14.40 7,0 10.50 21.00 31.50 42.00 52.50 63.00 73.50 84.00 2.50 4.90 7.40 9.80 12.30 14.70 17.20 19.60 2.10 4.20 6.30 8.40 10.50 12.60 14.70 16.80 8,0 12.50 24.00 36.00 48.00 60.00 72.00 84.00 96.00 2.80 5.60 8.40 11.20 14.00 16.80 19.60 22.40 2.40 4.80 7.20 9.60 12.00 14.40 16.80 19.20 9,0 13.50 27.00 40.50 54.00 67.50 81.00 94.50 108.00 3.20 6.30 9.50 12.60 15.80 18.90 22.10 25.20 2.70 5.40 8.10 10.80 13.50 16.20 18.90 21.60 10,0 13.50 27.00 40.50 54.00 67.50 81.00 94.50 108.00 0.00 9.00 12.00 15.50 18.00 21.00 24.00 Difference in temperatures (°C) ΔT = T operating temperature - T installation temperature Difference in temperatures (°C) ΔT = T operating temperature - T installation temperature
Table 7
Linear expansion of Dacta Therm Solid PP-R pipes Linear expansion ∆L (in): Dacta Therm Standard PP-R Pipe = α - 0.150 mm/mK
Linear expansion of Dacta Therm- fiberglass reinforced PP-R pipes Linear expansion DL (in): Dacta Therm - Fiberglass Reinforced PP-R Pipe = α - 0.035 mm/mK
The linear expansion is calculated according to the following formula: ∆L = Lo x α x ∆T ∆L : Amount of elongation α
: Linear expansion coefficient
Lo ∆T
: First length
: Difference in temperatures
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