Backflow Prevention Devices

An introduction to Fluid Categories and Backflow Prevention Types to ensure the safe delivery of wholsome water

European / UK ClassificationSuitable Backflow Prevention Device
Fluid Category 5Air Gap – AA, AB / Pipe Interrupter – DC
Fluid Category 4RPZ – BA / Pipe Interrupter – DB
Fluid Category 3Double Check – ED
Fluid Category 2Single Check – EB
Fluid Category 1No 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