There are solutions that significantly improve safety of use, and here we mean, for example, a backflow preventer. It is worth learning more about it and getting to know the principles of securing the water supply network in a building.
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What is a backflow preventer?
A backflow preventer is a small mechanical device used to protect the water supply network in a building. It is worth knowing that various types of contamination can occur as a result of backflow. They then pose a potential pathogenic threat. There are several types of backflow preventers , which are selected for the building or installation. Here we distinguish BA valves . These are mainly backflow preventers. They are used in public places or multi-family buildings. In heating installations without inhibitors, backflow preventers from the CA family are used. There is also the EA family. These are valves that are extremely sensitive to pressure fluctuations.
Current building regulations require that every new building be equipped with a water supply system that has anti-contamination valves. They should meet the PN-EN 1712 standards. In Poland, the PN-92/B-01706 standard has been in force since 1992. It concerns the design of water supply systems. However, at that time, there was no requirement to use anti-contamination valves. You can only read the formulations on general safety principles.
The regulations changed in 1999 when Annex Az1 was introduced. At that time, the recommendations of pan-European standards also came into force. In 2003, the PN-EN 1717:2003 standard was published, in which you can read how important it is to introduce solutions that prevent secondary water contamination in water installations. The use of anti-contamination valves is currently necessary because it prevents contamination of drinking water. It is worth being aware that reverse flow can occur when the pressure in the water supply network drops. This happens, for example, when a pipe bursts or a major pump failure occurs. Reverse flow can also occur when there is a back pressure from a source outside the water supply installation. Water contamination would then pose a very high health risk. For this reason, an anti-contamination valve should be used, which prevents this type of safety.
How does a backflow preventer work?
The anti-contamination valve has a very simple 
method of operation. It opens access to atmospheric air inside the installation. This occurs when negative pressure occurs. The valve prevents contaminated water from being sucked into the installation. It prevents water from flowing back. Of course, the tightness of the non-return valve should always be carefully checked. This type of device has an inspection hole, which is located on the drain side. It is also important to know that when the shut-off valve is closed before the anti-contamination valve, no further leakage should occur.
The operation of the anti-contamination valve is based on specific phenomena. In this case, the vacuum breaker opens automatically with a pressure drop. This prevents a pressure difference in the inlet direction, while the non-return valve closes when water flows in the opposite direction. Aeration can occur naturally through atmospheric pressure and this should also be taken into account.
Where should the anti-contamination valve be installed?
Legal regulations require the installation of a backflow preventer. It should be located at each connection of the internal cold water installation or external installation on the building plot with the water supply network. In such a case, a main water meter set should be installed. It is best to install the backflow preventer at the initial point in the water supply network.
The appropriate place will be the section located behind the water meter on the installation side. Many people wonder whether the anti-contamination valve can be installed vertically. The answer is yes. It can be installed in both vertical and horizontal installations, but on condition that the medium flows from the bottom to the top. There must also be a possibility of taking water samples. The Regulation of the Minister of Infrastructure of 12 April 2002 imposes the obligation to install an anti-contamination valve behind each set of the main water meter on the installation side.