Check valve for sewerage: types, types, installation

At times, we are faced with a situation where their contents flow through the sewer pipes in the opposite direction. The main reason for this phenomenon is a blockage in the sewer. In a private house, this can happen when the well overflows. It is possible to avoid such trouble. You need to put a check valve on the sewer. This simple but effective device completely blocks the reverse flow of drains. 

Why and who needs it

The purpose of the sewer check valve is to block the flow of fluid going in the opposite direction. In this regard, the main area of ​​uXNUMXbuXNUMXbapplication looms – lower-floor apartments in high-rise buildings, especially in old buildings.

In multi-storey buildings, the owners of apartments on the first floors very often have problems with toilet bowls, from which the contents of the sewer flow. The blockage usually occurs somewhere in the “beds” – horizontal pipes in the basement. Then all the contents rise through the pipe to the first branch and pour out through the first available point – the toilet bowl, spill onto the floor, sometimes even bathtubs and washbasins are filled. Here, to solve this problem, it is necessary to put a check valve on the sewer. It will cut off the return flow going to your apartment. True, those who live on the floor above will have a problem – fecal water can even rise there. Then they will also have to install a sewer check valve. Above this level, the drain column usually does not rise – it pushes through the cork, everything goes away.

However, residents of high floors should not rejoice – they can also suffer. Sometimes blockages happen somewhere between floors. This comes mainly due to violations of the rules for operating the sewer – someone lowers objects that should not be there, they get stuck, a traffic jam forms. In this case, toilet bowls on any floor can “gush” – it depends on where the blockage has formed. So on any floor, except for the last one, it makes sense to put a check valve – “just in case”.

The third group of consumers are the owners of private houses. In principle, the sewerage of a private house should be designed so that the reverse flow of drains is impossible. Even so, many prefer to play it safe than to scoop out foul-smelling “treasures” from the house later. The non-return valve for the sewer in a private house also performs another function – it does not allow rodents and other living creatures to penetrate through the sewer pipe.

Ventilation in the bathroom and toilet is described here. 

Types of check valves and the principle of their operation

The main task of the check (shut-off) valve is to block the flow going in the opposite direction. To do this, a movable barrier is placed in these mechanical devices. The basic principle of operation is that in a calm state, the mechanical damper is lowered down, blocking the lumen of the sewer pipe and preventing the reverse flow from passing. When drains appear, it rises (moves to the side), the drains leave, and it closes again. By the type of this barrier and the principle of its operation, this equipment differs.

Swivel (petal)

In sewer valves of this type, a spring-loaded round membrane (plate) is installed. If the flow moves in the “right” direction, it turns, rising up does not prevent drains from leaving. If the movement starts in the other direction, the membrane (plate) is pressed against the rim inside the valve, tightly and hermetically blocking the pipe lumen. Some models have a manual shutter. This is the second membrane, which can be controlled using a button mounted on the body.

Due to the shape of the membrane, such shut-off valves are also called petal valves, and sometimes you can hear the term “slams” – this is because of the way they work – the membrane slams if there is no drain.

The device itself is larger than the pipe on which it is installed. So in the pipeline there is first an expansion, and then a narrowing of the lumen, and these are potential places for blockages to form. To be able to quickly eliminate blockages, a removable cover is made in the upper part of the check valve body. By removing it, the problem can be quickly eliminated.

Lift check valve for sewerage

This type of locking device for a sewer pipe is so named because when the drains pass in the “correct” direction, the locking element rises. Drains press on the plate blocking the passage, compressing the spring, which rises. There are no drains – the spring is unclenched, the passage is locked. When effluents come in from the “wrong” side, there is no way to open the passage. This is achieved by a non-linear hull shape.

The lift check valve is more reliable, but its design is such that it often clogs and requires periodic cleaning. Why do you need to remove the cover (unscrew four bolts), clean or replace the mechanism.

Ball check valve

Another option for a locking device in a check valve is a ball. In these devices, the internal structure of the case plays an important role. Its upper part is designed in such a way that when passing drains, the ball rolls into a special recess in the body, opening the passage.

When it is dry in the pipe, it blocks the section; when the flow passes in the opposite direction, it blocks the lumen of the pipe. The main disadvantage of this design is the leakage of drains during flooding – the ball and the side wall of the body do not always fit perfectly, which leads to the fact that some of the drains still seep through. But mass flooding and a geyser from the toilet will not be for sure.

Why you need an air valve in the sewer and how to install it, read here.

Wafer type

Many people like this type of check valves more because of their miniature size. This is a very small cylinder, inside of which a rotary damper is installed. It may consist of two parts that are attached to the central rod, or it may look like a small plate, attached to the housing wall in one place with the help of a spring.

Despite its compactness, it is better not to install this type of check valve on the sewer: this is plumbing equipment and it will not work well on the sewer. The second disadvantage is the impossibility of quick cleaning – the design is such that you can get to the valve only by disassembling the connection.

What are they made of and what sizes are there?

The most common sewer check valves are made of plastic (PVC) and cast iron. If your sewer pipes are plastic, it makes sense to install the same valve, choosing it in size. Exactly the same situation with cast iron. The point is not that the materials do not fit, but the need for additional adapters that make the design even more cumbersome.

According to the installation method, the shut-off valve for the sewer can be horizontal and vertical. Choose the type depending on the installation location. It must be installed with the same diameter as the pipe, narrowing is not allowed. Accordingly, there are valves for each size. The parameters of some are given in the table.

When and where to put

As already mentioned, the sewer check valve is a rather bulky device. In apartments, bathrooms are usually small, it’s difficult to find a place, but you have to – if you don’t want to have a geyser instead of a toilet bowl.

The exact dimensions of the sewer valves depend on the diameter of the pipe on which the device is placed. For example, for a 100 sewer pipe diameter, the minimum length is 40 cm, the height and width are slightly less. Such a box must be installed before entering the riser.

In this case, it is often necessary to break the floor, the tiles already laid – it is necessary to combine the holes in the body with the pipes, center everything, follow the required angle of inclination. Such a prospect is especially “pleasing” if a renovation has recently been made. In this case, there is also an option – to embed a check valve in the riser above your entrance. But for such work – interference in the general house system (the installation of plumbing fixtures on your branch does not fall under this category), and they require written permission, you will have to notify the residents, turn off the water, representatives of the operating organization or the water utility will work. In general, it’s still a hassle, because this method of solving a problem is used very rarely.

If there was no place for a common device, they put back sewer valves on each plumbing fixture – separately on the toilet, bathtub, washbasin, sink, etc. This is if pipes from each of the devices separately go to the riser. If you have only two directions – to the toilet, and then to the bath-washbasin-sink, etc., then it will cost to install two devices – one personal on the toilet (the diameter matches the diameter of the outlet pipe) and the second – common, on a branch that goes to all other devices. Its size must match the diameter of the wiring pipe, and most often it is 50 mm.

How to install a toilet with your own hands, see here. 

Installation rules

The main thing to consider is the direction of movement of effluents. It is marked with a large arrow on the body. The device must be rotated so that the normal direction of the drains coincides with the arrow. The following are the features of the installation:

• The installation of a plastic check valve on the sewer takes place in the standard way for this type of pipe: there is a socket and sealing gum. The straight end of the pipe is inserted into this socket. Such a connection is already tight, but for greater reliability, the junction can be additionally smeared with sanitary silicone.
• Installation of cast-iron models – with the help of sealing rubber bands and bolts that tighten the mounting plates, there are models with sockets – for traditional installation on tow and filling the seam with sealant.
• It is necessary to set it so that there is free access to the lid – periodically the check valve for the sewer becomes clogged, so it must be cleaned.