|Calculation of Linear Expansion|
The linear expansion of pipe depends on the difference between the installation temperature and the operating temperature:
? T = Toperating temperature - Tinstallation temperature
Therefore, cold water pipes have practically no linear expansion. They can experience some contraction, but this is not a concern. The heat-fused connections will not pull apart.
Hot water installations can expand visibly and may require expansion loops or sliding elbows to prevent bowing or curving. Aquatherm has significantly reduced the issues related to heat expansion with the introduction of patented faser-composite pipes.
Aquatherm Faser-composite pipes
The faser-composite layer is a unique feature of Aquatherm piping systems. Made from a blend of the Fusiolen® PP-R material and e-glass fibers, this layer is perfectly integrated into the center of the Aquatherm pipes. By extruding this special layer into the center of the pipe, the exterior and interior layers remain unaltered.
The e-glass fibers expand less than the PP-R material when heated, which prevents the material they are bonded to from expanding. Because the faser-composite layer does not expand, the outside and inside layers can’t either, reducing the overall expansion and contraction of the pipe by 75% when compared to non-faser plastic pipes.
The faser-composite layer is only 18% glass fibers, so the fusion properties of the pipe remain the same. There is also no issue with recycling the pipe, as the fibers can be removed during the process.
Unlike most piping materials, PP-R is able to absorb the stress caused by expansion within certain limits. The faser-composite layer helps keep the pipe within these limits for most applications.
Concealed installations generally do not require additional consideration for the expansion of faser-composite pipes. Most insulations give enough expansion space for the pipe. In the case where the expansion is greater than the room to move in the insulation, the material absorbs any stress arising from a residual expansion.
The same applies to pipes which do not have to be insulated according to current regulations. The expansion on pipes that don’t need to be insulated is minimal because of the lower difference in temperature. The pipe itself can absorb the remaining stress.
Embedding the pipe in concrete or plaster will negate most of the linear expansion. The compressive strain and tensile stress arising from this are no longer critical, as the extra forces are absorbed by the pipe itself. This is also true of pipe that is buried in soil or sand.
In the case of exposed installations, it is important to maintain the visual trueness of the pipe as well as compensate for any expansive forces. Aquatherm’s faser-composite pipes make this an easy process.
It is important to calculate the expansion of the system and allow the piping to expand. Expansion can be compensated for using sliding elbows and expansion loops. The flexible heat fusion joints will not crack or leak from the tension of expanding and contracting if the bending side is long enough.