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Waste waters must be expelled and also be prohibited from returning !

A check valve is a device used in plumbing drains that prevents the flow of fluids (primarily sewage) from returning “backward”, i.e. in the opposite direction it is supposed to go: towards the outside of the building. outside of the building

The weather hazards of recent months: heavy rain s and ice, have exposed the need to protect properties with a functionning check valve gainst the backflow of sewage and rainwater, which have caused numerous insurance claims and damaged several residences in particular in urban areas. Check valves are used in residential, commercial and industrial plumbing.

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The operation mode of a check valve is quite simple, note that it is also mandatory equipment that must be installed on residential drain pipes to prevent backflows, article 2.4.6.4 of the Quebec plumbing code. Every owner must ensure that their non-return valve complies with the Quebec Construction Code. If you are not sure or suspect a break in yours, call a plumber for a camera inspection.

There are three types of check valves:

  1. normally closed check valve
  2. normally open check valve
  3. insertion valve (found on manholes)

The closed check valve its name describes quite well in which position it is oriented, is open to let the gray waters (waste) run which is then evacuated by the main drain towards the sewers. If, however, the latter become clogged with water and they begin to back up – return the water towards the residences and buildings – the valve will close and prevent any return of water.* Among the disadvantages of this type of valve: l lack of ventilation in the ducts. It must therefore be installed on a pipe that is otherwise ventilated.

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Closed check-valve

The open valve, you can probably guess its default position 😊 has the benefit of the disadvantage of its cousin (the closed valve), that is to say that it is permanently open which allows it to freely circulate the air. When the sewers back up, the valve closes, preventing wastewater from returning back into the pipes. This type of damper is only authorized on a single-family home (serving only one dwelling) and certain municipal regulations refuse its use, we recommend that you obtain detailed information from local public works. picture

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Open check-valve

In addition, if your residential building has a flat roof – for example a condo building, a multiplex – the presence of a normally open valve risks closing when the sewers back up; therefore rainwater risks causing significant damage to the property. Installing more than one check valve in strategic locations could therefore be the solution for you. If in doubt, an experienced professional will be able to advise you on this equipment.

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