Back flow preventers

Backflow prevention devices are used in potable water, industrial water, and fire protection systems to prevent reverse flow of contaminated or technically unsuitable water into the main supply. Backflow may occur either from upstream negative pressure, caused by supply interruption or pipeline rupture, or from downstream backpressure when the connected system develops a pressure higher than the supply line.

This category includes the Brandoni ECO 3F and ECO 3T, type BA assemblies in accordance with EN 1717, with a controllable reduced pressure zone and approval to EN 12729. The assembly consists of two spring-loaded check valves and an intermediate chamber with a relief valve, so that under backflow conditions the primary network is hydraulically separated from the user side system.

The ECO 3F is supplied with flanged ends, DIN drilling, EN-GJL-250 body material, and PN10 pressure rating. The ECO 3T is supplied with threaded ends to ISO 228-1, with body material in DZR brass or bronze depending on size, also rated PN10. Both types are specified for protection against water contamination up to fluid category 4 under EN 1717; for category 5 fluids, protection requires separation by air gap rather than a mechanical backflow preventer.

Installation should include an upstream strainer, isolation valves on both sides of the assembly, access for inspection of the intermediate zone, and provision for periodic functional testing. Selection should consider operating pressure, potential backpressure conditions, fluid category, discharge routing from the relief valve, and maintenance requirements in water distribution systems, boiler rooms, laboratories, industrial plants, and fire protection networks.