Shipping Notice: Orders placed between Monday And Friday before 15:30 will be dispatched the same day. Orders placed after the cut off time and weekend will be processed on the following business day.
Available for plumbing and heating spares orders placed before 4pm GMT
An introduction to Fluid Categories and Backflow Prevention Types to ensure the safe delivery of wholsome water
European / UK Classification
Suitable Backflow Prevention Device
Fluid Category 5
Air Gap – AA, AB / Pipe Interrupter – DC
Fluid Category 4
RPZ – BA / Pipe Interrupter – DB
Fluid Category 3
Double Check – ED
Fluid Category 2
Single Check – EB
Fluid Category 1
No device required
Fluid category 1
Wholesome water supplied by a water undertaker and complying with the requirements of regulations made under section 67 of the Water Industry Act 1991(1).
Fluid category 2
Water in fluid category 1 whose aesthetic quality is impaired owing to–
(a)a change in its temperature, or
(b)the presence of substances or organisms causing a change in its taste, odour or appearance,
including water in a hot water distribution system.
Fluid category 3
Fluid which represents a slight health hazard because of the concentration of substances of low toxicity, including any fluid which contains–
(a)ethylene glycol, copper sulphate solution or similar chemical additives, or
(b)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–
(a)chemical, carcinogenic substances or pesticides (including insecticides and herbicides), or
(b)environmental organisms of potential health significance.
Fluid category 5
Fluid representing a serious health hazard because of the concentration of pathogenic organisms, radioactive or very toxic substances, including any fluid which contains–
(a)faecal material or other human waste;
(b)butchery or other animal waste; or
(c)pathogens from any other source.
Backflow Prevention Device
Type BA – Verifiable backflow preventer with reduced pressure zone
Type CA – Non-verifiable disconnector with different pressure zones
Type DA – Anti-vacuum valve (or vacuum breaker)
Type DB – Pipe interrupter with atmospheric vent and moving element
Type DUK1 – Anti-vacuum valve combined with a single check valve
Type EA – Verifiable single check valve
Type EB – Non-verifiable single check valve
Type EC – Verifiable double check valve
Type ED – Non-verifiable double check valve
Type HA – Hose union back flow preventer
Type HC – Diverter with automatic return
Type HUK1 – Hose union tap incorporating a double check valve
Type LA – Pressurised air inlet valve
Type LB – Pressurised air inlet valve combined with a check valve downstream
Please follow the link below to view our available Backflow Prevention Devices
Backflow Prevention Devices
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