FAQ - Fränkische Rohrwerke

Q: Can alpex pipe connections be used for concealed installations or under screed?

The alpex pipe and system connections for drinking water and heating installations are suited for concealed installations or installations under screed without any concerns. For detailed information, please refer to DIN 1988 / DIN EN 806.

Q: Is it necessary to insulate alpex multilayer composite pipes for cold water lines against condensation water?

Yes, insulation of cold drinking water pipes is required according to DIN 1988-200 tab. 8 and 9 in order to prevent condensation and to protect drinking water from warming-up due to elevated ambient temperatures. Pipes that come into contact with the structure (floating, screed, etc.) must be protected with at least one layer of insulation (pipe with protective sheathing). Sound insulation according to DIN 4109 must be provided. Appropriate insulation is recommended for prevention of cracking and flow noise.

Q: Are alpex installations possible with de-mineralised water?

No, since the installation of multilayer composite pipe systems usually includes brass fittings. Brass fittings may be affected by corrosion damage in connection with de-mineralised water (aggressive).

Q: Are alpex installations possible with softened water?

Yes, alpex installations (pipe + PPSU + brass) can be operated with softened water of up to 0°dH. The limit value for sodium ions of 200 mg/l may not be exceeded during softening. For reasons of corrosion protection, it is recommend that the water hardness level should be of at least 3°dH. If drinking water is intended for human consumption, water hardness of 4 to 8°dH is ideal.

Q: Can I use antifreeze agents with alpex multilayer composite pipes?

The alpex multilayer composite pipes can be used with antifreeze agents at temperatures between -20 °C and +95 °C (max. permissible continuous operating temperature) and a maximum constant operating pressure of 10 bar. However, make sure that the antifreeze agent used has no impact on polyethylene, EPDM, PPSU and brass. For reasons of corrosion protection, minimum concentration shall not fall below 25 % vol.

Q: Can I use alpex multilayer composite pipe systems in stables?

The alpex multilayer composite pipe system is limitedly resistant to ammonia content in the atmosphere that often occurs in stables. Corresponding alpex fittings and connectors, however, are exposed to a high risk of corrosion under these conditions. The installation should therefore be of concealed type. If it is not possible, fittings and connectors must be protected by means of appropriate measures such as wrapping in a corrosion protection tape (e.g. DENSO tape, KEBU tape) or a vapour-tight insulation (e.g. Armaflex). We recommend that the alpex system should be protected with a vapour-tight insulation.

Q: Are alpex multilayer composite pipes free from plasticisers and CFC?

Yes, alpex composite pipes are free from plasticisers and CFC, since pure polyethylene (PE) is used as a material during production. Thus, there are no materials that emit gases as is the case with e.g. PVC.

Q: How do I pressure test drinking water installations with alpex?

Pressure testing must be carried out according to DIN EN 806-4 and the ZVSHK advisory leaflet "Leak Testing of Drinking Water Installations" (Dichtprüfungen von Trinkwasserinstallationen). Detailed requirements of pressure testing must be complied with depending on the test medium (water or air); please refer to pressure test reports water / air available in the download centre.

Q: What applications can I use alpex multilayer composite pipes for?

The alpex multilayer composite pipes can be used for various media, such as drinking water, heating, stormwater and compressed air. Please refer to the alpex Technical information for more details.

Q: Up to which max. heat capacity can I connect alpex pipes?

Please refer to the Technical information for detailed alpex performance and pressure loss tables for heating applications. We recommend that the following standard flow values are not exceeded when designing the pipework system: Radiator connection pipe ≤ 0.3 m/s Radiator distribution pipes ≤ 0.5 m/s Heating riser and basement pipes ≤ 1.0 m/s The max. pressure loss in the pipe must not exceed 2 mbar/m.