Additional Information

Site Information

  • Image 1
  • Inline Backflow (Non Return Valve) installed on a Waste Pipe under a Sink.
  • How the Non Return Valve works.
  • Lockable Lever on the 50mm Back Flow Valve enables it to be closed off in emergencies or maintenance of plumbing systems.
  • Dimensions of the 50mm Backflow Valve.

Inline Backflow Valve - Anti Flood Non Return Valve, 50mm


Prices include VAT


Product Description

Backflow Prevention Device (BPD) for 50mm Waste Pipes (Grey)

These Backwater Non Return Valves (NRVs) protect buildings against flooding from back flow of storm water and sewage travelling back up the sewerage, drain or toilet systems during intense rains, thaws, floods or blockage of nearby drainage-related systems such as toilets, washing basins, kitchen sinks, shower bases and dishwashers.

Suitable for Waste Pipes as well as Water and Rainwater Pipes. The simple and effective design also inhibits unpleasant smells from the sewage or drainage system.

KARMAT backwater valves are equipped with a manual closure lever. Changing of the lever from OPEN position to CLOSED position causes a complete arrest of sewage/grey water backflow in emergencies or for maintenance/plumbing works. The interior of the non return valve is smooth ensuring non-interrupted flow water through the device.

The flap guard (as well as all assembly elements (screws, nuts, washers)) are made from corrosion resistant chromium nickel giving effective protection against rats and other rodents.

The backflow valves are a perfect solution where it is impossible to install a non-return valve to protect the whole building e.g. in an apartment block or where access to the main sewage pipe is difficult. It can be installed in such a way as to protect several facilities at the same time if they are connected to the same sewage system such as a bath or shower base traps.

Meets the requirements of the standard EN 13564-1 and they are marked with the CE mark.

How does the Backflow Valve Work?

The Backflow Prevention Device has a Single Flap that allows sewage to flow through it from one direction, but the flap closes tightly shut when sewage or water pushes at it from the other direction. This simple mechanism ensures that, during flood events, basements and rooms located at lower levels are protected from sewage from the sewer system. It is a fully automatic operation that requires no external power supply and includes a lockable lever for emergency lockdown of the pipe network or for maintenance.


Comes with 24 months warranty from the date of purchase when the buyer adheres to the guidelines in the instruction manual (included).

Technical Information

  • Body Material: High Quality Polypropylene
  • Colour: Grey
  • Single Flap design
  • Flap Guard Material: Corrosion resistant chromium nickel
  • Screws, nuts, washers: Corrosion resistant chromium nickel
  • Gasket Material: Rubber
  • Self Operating (Automatic) Mechanism with Lockable Lever for emergency closure
  • Suitable for 50mm Horizontal Sewage Pipes as well as Water and Rainwater Pipes.
  • Maximum operating temperature 95°C
  • Maximum operating pressure 0.5 bar
  • Meets BS EN13564-1
  • CE Mark

Included Components

  • Backflow Valve (Grey)
  • Installation Instructions with Guarantee Card in English, Polish, German, Russian.

Other Options

  • Backflow Valves for 110mm Vertical Pipes
  • Backflow Valves for Horizontal Pipes 110mm, 160mm and 200mm

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