Preliminary calculations at the device of the sewerage protect from potential technological problems, for example, from a blockage. Properly selected pipe diameter and proper installation ensure long and comfortable use of the waste system.
One of the important indicators in the design and construction of communications is the slope of the sewer pipe, necessary for the free movement of wastewater.
We will tell you how to calculate a sufficient angle of inclination of the pipeline, which rules should be followed when setting up an internal and external sewer system.
The content of the article:
- What is the slope angle of sewer pipes
- How the functionality of the system depends on the slope
What standards must be observed
- Features of the house sewer
- Sample internal layout project
- External pipe laying
- How to control the slope
- Calculation of the level of fullness of the highway
- Conclusions and useful video on the topic
What is the slope angle of sewer pipes
One of the principles of installation of pipes, which is used in practice by experienced builders, is the possibility of installing a line so that the waste water moves by gravity. This principle is used everywhere - and in the arrangement of apartments in high-rise buildings, and in the construction of private 1- or 2-storey cottages.
Horizontal elbows, for which they calculate the angle of the slope, are installed after the risers are laid and fixed - vertical sewers. Risers have a larger diameter than the other pipes.
Horizontal branches are attached to the risers with the help of fittings (tees) and are directed towards the sanitary appliances (toilets, sinks, bathtubs, shower stalls) along the smallest path.
Most often, near the sprue mount toilets - sanitary appliances, "giving" the most solid waste. The shorter the path of movement of solid waste to the exit, the less likelihood of congestion
And now let us analyze the definition of the angle of inclination of a horizontal sewer pipe - external or internal.
Imagine that a straight line runs along the laid highway, parallel to the floor or surface of the earth in the case of external pipes. If the beginning of the line is connected to the lower end of the pipeline, then we get an angle - with proper installation. This is the slope angle.
It is measured in degrees or, which is easier to read, in centimeters per meter - cm / bar.
In the course of construction, for ease and ease of calculations, they simply tension the horizontally aligned cord. Its beginning is fixed at the lowest point of the highway, and the end is brought under the top. Angle measurements are relative to it.
The slope calculation is directly related to pipe parameters such as length and diameter.
According to the standards set forth in the SNiP, the diameter of the horizontal branches of the internal wiring should meet the following standards:
- D 40-50 mm - from dishwashing or washing equipment;
- D 50 mm - from sinks, sinks, bathtubs, urinals (that is, appliances with liquid drains;
- D 110 mm - from toilet bowls.
For external sewage, a diameter of 110-160 mm is provided.
There are options when you have to combine pipes of different diameters. For example, a toilet bowl pipe is attached to a tap from a sink (50 mm). Obviously, an adapter to a 110 mm (+) pipe is required
It is important to choose the right diameter and slope of communications, otherwise the system will often fail. Consider the possible negative effects.
How the functionality of the system depends on the slope
In the process of installing the sewer system, pipes are laid either directly (parallel to the floor) or at a certain angle. The first option is clearly erroneous, since it blocks the movement of stocks and, ultimately, makes the entire system inoperable.
Judging by the photo, the pipes are not even laid parallel to the floor, but with some inclination towards the bath - that is, it is wrong. When you turn on the water in the sink, it will flow not in the direction of the riser, but straight into the bath
The second solution is correct, but it can be executed in different ways:
- Ensure the sharpest angle possible.
- Minimize slope.
- Perform installation, focusing on the figures recommended by regulatory documents.
What happens in each of these cases?
Option 1. It would seem that too sharp a corner, therefore, a steep descent of drains is not dangerous. This opinion is erroneous, as the rapid flow of a liquid does not fully erase the solid waste.
As a result, they accumulate and form blockages. The second trouble is associated with a breakdown hydraulic locksThe result is a peculiar smell of sewage in the whole house or apartment.
Another undesirable and disturbing comfort effect is loud noise, which is generated at high speed by falling down sewage.
Option 2. The minimum slope is not much different from horizontal installation. Slow movement of the fluid leads to silting, the formation of a thick layer of dirt on the pipe walls, and then regular blockages. By the way, the SNiP recommends sticking to the speed of drains in the range of 0.7-1.0 m / s.
Option 3. The most optimal solution is to ensure the slope specified in the regulatory documentation, where the dependence of the laying angle of the pipeline on the diameter or length of the pipe is indicated. We turn directly to the norms and calculations.
What standards must be observed
We will dwell more on building codes, which are detailed in the SNiP. About the features of the internal sewage can be read in SNiP 2.04.01-85, external - SNiP 2.04.03-84. It is also useful to refer to the regulatory documentation GOST 25150-82.
Features of the house sewer
There are two options. domestic sewage - hidden and open installation. The first is the masking of the wiring behind the wall panels, under the floor covering and in the floors, the second is to lay on the open areas.
One of the options for hidden installation - full or partial penetration into the walls. In brick and panel houses for this type of camouflage, shaving is practiced followed by finishing - plaster, drywall, ceramic veneer
The type of installation, in particular, determines the permissible length of the pipeline:
- hidden lines must be no longer than 10 m;
- open pipes may be of greater length, but subject to installation under a certain slope and with free access for maintenance purposes.
The diameter of the pipes must necessarily coincide with the diameter of the releases from the sanitary devices. For joining highways to the risers, shaped elements are used - crosses and direct tees for connecting at 90 ° and oblique for fixing at 45-60 ° angles.
Despite the correct, with a slope, the location of the hidden pipes for the purpose of maintenance arrange inspection cameras - both at the corners and on long straight sections of the highway (+)
Demands are also made on turns: they must be smooth, from 90 ° or more, that is, not sharp. For a safer change of direction, the pipes create a two-turn construction of 135 °. When connecting parts, the bell should be turned against the flow of wastewater. The only exception is the installation of double-socket couplings.
In SNiP specified allowable slope of sewer pipes. The data are given in the following table:
Regulatory values are given depending on the diameter of the pipes, in units that are read as the number of centimeters per linear meter. For example, when installing branches with a diameter of 50 mm, it is necessary to withstand a slope from 0.025 m to 0.035 m (from 2.5 cm to 3.5 cm per meter) (+)
It turns out that when the length of the sewer line is 5 m, the difference in height above the floor between the beginning and the end of the pipe is 12.5 (17.5) cm = 2.5 (3.5) x 5.
Let us return to the "help" of the building cord - it can just be useful. If you stretch it along the entire length of the pipe, but parallel to the floor, it just happens that the distance from the cord to the lower end of the line is 0 mm, and to the upper end - 12, 5 (17.5) cm.
As is clear from the table, with an increase in the diameter of the pipe, the slope value decreases, that is, for D 110 mm, the optimum angle of inclination is 2 cm / running meter.
The table presents the minimum values of the norms. There is also a maximum slope - it is 0.15 m / rm. The value is relevant for pipes of various types and sizes, except for the shortest branches, whose length is less than one and a half meters.
It can be concluded that the slope angle for domestic sewage pipes should be between the data from the table and 15 cm / rm.
Sample internal layout project
The project should begin with the drawing up of diagrams, drawings and sketches with simultaneous calculations relating to all taps.
Special attention should be paid to the following points:
- the location of pipes, fittings, connections;
- diameter of pipes and fittings;
- the length of each section to the riser;
- floor height or elevation of floors, niches, etc.
In addition to accurate measurement values, tolerances should be taken into account: for each branch of the main line ± 20 cm, for the length of the riser and for the outlet ± 1.5 cm.
Sample metering card for the installation of sewer pipes for two apartments connected to a common riser. The two parts are absolutely identical and are located in a mirror image (+)
For this scheme sewer comb important measurements of the distance between individual points, namely the central axes:
- standpipe and car wash;
- bathtubs and washbasin;
- toilet bowl and washbasin.
It is also necessary to take into account the thickness of the wall that separates the plumbing blocks of two adjacent apartments.
Read more about the design of the internal sewer layout of a private house in the this article.
External pipe laying
Unlike pipes of the internal sewerage which can be both opened, and disguised in overlappings, external highways belong to the hidden communications - pipeline is placed in the ground.
Pipelines most often have an outlet at the basement level of a house and lead to sewage treatment or storage facilities. Throughout their length, they should have a diameter of at least 110 mm and a clearly marked slope of 0.02 m per linear meter.
In addition to the mandatory bias to external highways, there are a number of requirements. For example, they should also be equipped throughout. manholes.
If the highway is straight, then a well is arranged every 10 m, if it has bends, then it is also in the places of turns. Technical wells are also required where several highways intersect or have a stepped transition.
The maximum number of inspection wells is necessary in order to foresee blockages in the most susceptible places: corners, junctions, etc. (+)
For outdoor sewage use different types of pipes, their cross section is from 110-200 m. As we have already found out above, the gradient depends on the internal diameter of the pipeline, therefore we take this into account when setting up trenches and laying communications.
Do not forget that for large diameter pipes, smaller values apply:
- with D 150 mm - from 0.007 m to 0.01 m;
- at D 200 mm - from 0005 m to 0.008 m.
These are the minimum values. When installing a short piece of pipe with a large cross-section, a miserable incline can be imperceptible, but for long pipelines the differences can be pronounced.
For example, when laying a pipe with a diameter of 15 cm, it was decided to make a slope of 1 cm / meter. It turns out that for every 10 m the difference is 10 cm, and after 100 m - 1 m. This must be taken into account and combined with the parameters of GWL, as well as with indicators of the level of freezing. ground.
How to control the slope
For an example of mounting an external highway, let's take the laying of a single straight pipe leading from the building to the septic tank.
The purpose of the pipe is to move sewage coming from plumbing fixtures to the common tank. These include fat waste from the kitchen sink, and fecal matter from the toilet bowl, and dirty water from the shower stall.
It is reasonable that the pipe should be at least 110 mm in cross section. It is important for us that the required slope is maintained throughout the pipe, in this case - 0.02 m / running meter.
Using a laser level, you can measure the angle of inclination at different stages of work. The photo gallery will help to visualize the working areas under control.
A photo of
The first measurement of the angle of slope should occur at the stage of digging the trench
Check the angle you need and after the device gravel-sand "pillow" - the base under the pipe
The following measurement is necessary after the main line is insulated, if it is required by the climatic conditions and installation features
Another critical place - at the entrance to the opening of the storage tank
1st stage - trenching
2nd stage - sand cushion device
3rd stage - pipe insulation
4th stage - entering the tank
If the angle of inclination is maintained in all places, there will be no problems with the movement of sewage. However, it should be remembered that the result of unnoticed errors in the future may be a complete dismantling highway, therefore, each measurement must be approached very seriously and not “ peephole.
Calculation of the level of fullness of the highway
Additional calculations of the level of fullness, along with the angle of inclination determined by the norms of SNiP, ensure the smooth movement of sewage through the pipeline.
Calculations are made according to the formula:
Y = H / dwhere
- Y - the level of fullness;
- H - fluid level in the pipe;
- d - diameter
A value of 1.0 means that the highway is completely filled with drains - this can happen only if the layout of the wiring elements is absolutely horizontal.
The SNiP specifies the norms for the minimum and maximum permissible fullness - 0.3 and 1.0, respectively. That is, if the pipe diameter is selected correctly, the waste will move at the desired speed, not sticking to the inner walls (+)
In this regard, it is customary to take values in the range of 50-60%. In practical application, occupancy is taken into account, which is greater than 0.3 and less than 0.6. The optimal value is considered to be 0.5-0.6.
Let's try to calculate independently the speed of movement of the flow. According to regulations, it should be 0.7 m / s or more. Only at such values the liquid freely reaches the final goal.
Suppose that H is 60 mm and D is 110 mm, the pipes are made of plastic, that is, they have a smooth inner surface and a minimum degree of resistance. According to the formula 60 divide by 110, we get 0.55 - this is the level of fullness (Y), it corresponds to the norm.
Conclusions and useful video on the topic
Information from video clips will help you understand the complex nuances of installing a sewer pipeline.
An example of properly mounted pipes in the bathroom:
Detailed explanation of the theoretical part:
Useful device for observance of the slope:
Compliance with the rules when calculating the angle of the sewer pipe is of great importance in the technological plan. It is better to perform the calculations at the design stage of internal wiring or external piping.
If there are difficulties, we recommend to contact professional design engineers.
Is there anything to supplement, or are there any questions about the definition of slope and layout of sewer pipes? You can leave comments on the publication. The form for communication is in the lower block.