Drainage systems is a piping system which disposes household effluents. It consists of two features which work together: the outdoor and domestic pipelines.
Main requirements for outdoor systems
The outdoor drainage system is distribution pipelines which are extend from the building to the pump station where the waste water is stored. When designing the outdoor drainage system the requirements presented in the SNIP 2.04.03-85 should be observed:
- The minimum diameter of pipes and fittings for outdoor pipelines is 100 mm and in this case deviation is not less than 0.01%, and deviation for pipeline DN150 is 0.008%;
- The angle between the discharge pipe and affiliable pipe must be at least 90°;
- The minimum installation depth of the pipeline must be 0.7 m in areas where vehicles may ride, and in other areas it must be 0,5 m. However, the outdoor drainage system should installed below the depth of soil freezing. If installation of the pipeline below the depth of soil freezing is not possible, it should be insulated, that there was no obstruction of pipes.
Also when selecting pipes for outdoor drainage system and their installation you should take into account the following:
- For regular cleaning and maintenance of pipelines inspection chambers must be installed;
- If local factors do not allow to design gravity pipe system, force main sewerage should be installed, and for it the special pipes must be used - they are designed for the work under pressure. Usually they are made of cast iron, asbestos cement or plastic;
- Connections of the pipeline should not have displacement which disturb integrity of the system during seasonal increase level of ground waters;
- Pipes, which can withstand the load of vehicles and pedestrians, should be installed in areas that intersect with highways, as well as in areas with increased load.
Main requirements for domestic drainage systems
Domestic drainage system consists of the following elements:
- Plumbing fixture, work of which produces effluents (exception – heated towel rail);
- Pipes which dispose effluents from plumbing fixture to drainage system;
- Main sewer.
As for outdoor drainage system, specific requirements are developed, and they must be followed when installation of drainage system. All pipeline equipment for domestic drainage system should have high capacity - this will avoid frequent and time consuming cleaning of the pipeline. Also it should withstand test pressure which exceedes the working pressure by 1.5 times, but not less than 0.68 MPa or about 7 bar, and the permanent pressure corresponding to the operating pressure, but not less than about 0.45 MPa or 4.5 bar. Also the pipes should be:
- Durable;
- Resistant to low and high temperatures;
- Smooth inside – smooth inner surface allows to avoid frequent clogging;
- Mechanically and chemically wear resistant;
- Robust;
- Compatible with outdoor drainage system.
Additionally, you shoukd choose such pipes that are easy to install.
Basic requirements to storm-water drainage system
Storm-water drainage system is installed for diversion rainwater and melt water from roofs of residential and public buildings. Effluents are transported through storm-water drainage system to major stormwater drain.
Storm-water drainage system can be both above-ground and underground, and pipeline equipments for this drainage system should meet the following requirements:
- They should be resistant to UV - if pipeline is installed above ground, it is exposed to sunlight every day, so that equipment which is sensitive to UV light reduces durability of the pipeline;
- They should be strong - the storm-water drainage system should be high resistant to mechanical stress, because this system is built for several decades;
- They should be resistant to aggressive reagents - the the storm-water drainage system disposes not just rainwater, but also melt water in which can be a lot of aggressive reagents, because in the winter time the road is covered with chemicals;
- They should be resistant to temperature extremes.
When installing the storm-water drainage system you shoul consider the following:
- On the flat roofs of public and residential buildings you can install only one roof drain on section;
- Roof drains should be located at distance no more than 48 m from each other;
- You shouls install access pipes and manholes for cleaning of pipeline.
Operation rules of drainage systems
All drainage systems should be operated following the basic rules:
- Cleaning and maintenance of the pipeline should be carried out regularly;
- All of the pipeline elements must be sealed completely for reducing likelihood of leakage;
- Diameters of the pipeline equipments must be such that the wastewater will be disposed without interruption;
- You should avoid the overload not only the whole system but also its separate elements;
- You should monitor the concentration of toxic substances contained in the effluents, because high concentration of toxic substances can damage the treatment facilities
If you will observe this rules, the pipeline will serve a long time with minimum of failures.
