Linear expansion of polypropylene pipes

In the construction of modern buildings, as a rule, they use polypropylene pipes. They are easy to install and install, convenient to transport, they do not make a lot of noise. Structures made of polypropylene are modified more metal in length when temperature indicators change, that is, they lengthen with increasing temperature and decrease with cooling. For this reason, the thermal expansion of a pipeline made of polypropylene is certainly calculated when designing a pipeline system with a long length. Taking into account that temperature transformations in the cold water supply system are not expressed, the expansion of polypropylene pipes is not taken into account. They attach importance to the linear expansion parameter only in heating systems and in hot water supply.

At system installation, designs are set so that they easily move within the boundaries of the design expansion parameters. A similar alignment can occur as a result of the compensating ability of the pipes, mounting temperature compensators and the proper settings of the fasteners.

What happens when neglecting thermal expansion?

1. The increase in temperature in polypropylene pipes can contribute to pulling out clips and other compounds. A similar effect occurs in long sections (over 10 meters) of the heating pipeline.
2. Air chambers appear in the uppermost sections of the pipeline system. In this case, the cross section of the pipe narrows, the throughput decreases, and therefore, it takes on a wave-like shape.
3. Battery warming up in the heating system it becomes smaller, the pressure of hot water decreases. There are cases when the linear expansion of polypropylene pipes causes a breakdown in the heating system.

Linear Expansion Ratio Considerations

When creating pipeline projects, the coefficient of thermal elongation is taken into account.

Calculating changes during heating, the standard expansion coefficient and the indicator of the difference in temperature values ​​outlined in the pipeline when the system is turned on and during installation are used.

In unreinforced structures, the coefficient of thermal expansion corresponds to 0.15 mm / mK, in reinforced pipes, a similar indicator ranges from 0.03 ─ 0.05 mm / mK. A pipe reinforced with fiberglass or aluminum has a low coefficient, unlike polypropylene pipes. When mounting systems, this fact is decisive.

It is necessary to take into account the length of the pipes, calculating the value by which the structure lengthens when heated. For example, when the length of the pipeline section is 5 m, the expansion value reaches 17.5 mm.

Ways to eliminate the effect of thermal expansion of pipes

• When installing a heating system, a certain size of gaps is assumed between the pipeline and the wall. Consequently, the pipes have the opportunity to expand when heated by several centimeters. In order to avoid a complete breakdown, the heating system is not laid strictly along the walls;
• Most carefully, it is necessary to monitor the soldering of polypropylene pipes in areas of the corners of the room. It is necessary to maintain gaps of a certain size to prevent the pipes from stopping against the wall;
• On sections of a continuous pipeline, special compensators are required to be installed. In U-shaped zones, thermal expansion promotes the mobility of polypropylene pipes. So that the air chambers do not form in the upper sections of such compensators, they are installed with an inclination. In this case, during the filling of the system with hot coolant, air plugs will leave them;
• With the proper use of supports and the selection of a certain shape of the pipeline, the problem of linear expansion is eliminated.
• The main mounting recommendations: a flexible system device, with a minimum number of rigid joints with a low ability to deform.

Polypropylene pipes, subject to the manufacturer's recommendations and installation rules, differ from other types of their low cost, ease of installation, long life and security.