BACKFLOW PREVENTION
WHAT IS BACKFLOW AND WHEN CAN IT OCCUR? ALTECNIC HAS THE SOLUTIONS…
Backflowprevention inmodern systems
P otable water from the mains system may suffer from hazardous pollution caused mainly by contaminated fluids from plumbing systems flowing back directly into the mains supply. This phenomenon, termed “back flow”, occurs when: a) the pressure in the main water system is less than that in the downstream circuit (back siphoning). This situation may occur when a pipe is broken in the mains system or when consumer demand on the mains supply is very heavy; b) the pressure in the downstream circuit rises (counter pressure) due, for example, to water being pumped from a well. A backflow prevention device is used to protect potable water supplies from being contaminated or polluted. These include RPZ valves, double check valves, single check valves, non-return valves and are used in both domestic and commercial systems. LEGISLATION In the case of RPZ valves, in the UK there are legal requirements regulating water installations in domestic, commercial and
healthcare premises. The legislation that governs water installations within private premises is set out in: • The Water Industry Act 1991 • The Water Supply (Water Fittings) Regulations 1999 • The Water Byelaws 2000, Scotland • European Standard/British Standard 1717 To prevent the contamination of the wholesome water supply system, the Water Regulations require backflow protection devices to be installed at or near to all points where water is to be drawn off for use. FLUID CATEGORIES As part of regulations, Fluid Categories identify the level of contamination risk that needs to be prevented. They include: Fluid Category 1: Wholesome water supplied by the undertaker and complying with the requirements made
under section 67 of the Water industry Act 1991/ the Water Supply (Water Quality) (Scotland) Regulations 1990 and any amendment. Fluid Category 2: Water in fluid category 1 whose aesthetic quality is impaired owing to:
- a change in its temperature, or - the presence of substances or
organisms causing a change in its taste, odour or appearance, including water in hot water distribution systems. Fluid Category 3: Fluid which represents a slight health hazard because of the concentration of substances of low toxicity, including any fluid which contains: - ethylene glycol, copper sulphate solution or similar chemical additives, or - sodium hypochlorite (chloros and common disinfectants) Fluid Category 4: Fluid which represents a significant health hazard because of the concentration of toxic substances, including any fluid which contains:
“The device should be well suited to the system to ensure the safety of the end user.”
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