Building drainage
It is very essential to provide various facilities for drainage of building in order to maintain good healthy environment. For this purpose it is very essential to provide various fitting such as wash basins, sinks, water closets, urinal etc. in order to provide the entry of foul gases into the building traps have to be provided.
The arrangement provided in a building for collection and carrying the west through drain pipes gravity to join sewer is referred as building drainage.
Aims of building drainage
The aims of providing drainage facilities in a building are
1. To provide healthy condition in the building.
2. To depose of liquid waste as early as possible.
3. To avoid the entry of foul gases from the sewer.
4. To provide facilities for the quick removal of foul matter eg. Human excerta
5. To collect and remove the waste matters systematically.
Requirements of sanitary fitting
The requirement of sanitary fitting depends upon the type of the building of the people type of the area etc. For office building following approximate requirement can be used for calculating the number of sanitary fitting.
1. Urinals
1) Upto 20 persons
2) From 21 to 45 person
3) From 46 to 75 person
4) From 76 to 100 person
Add 3.5 % for the next 100 i.e. upto 200 and over 200 add 2.5 %
2. Wash basins
1 for every 20 person
3. Bath
1 for each floor
4. Water closets
1 for every 20 person
5. Drinking foundation
1 for every 100 person
6. Cleaner’s sink
1 for each floor
Traps
The depression or bend provided in a drainage system which is always full of water to prevent the foul air or gases to entre in the atmosphere is called a trap.
The trap prevents the passage of foul gases through it but on the other hand it allows the sewage to flow through it.
Diagram
Requirement of good trap
The following are the requirements of good trap
1. It should be made upto a non-obserbent material.
2. It should provide an adequate water seal at or times.
3. It should not restrict obstruct or retard the flow of water by presenting any rough surface projection angles or contraction inside it.
4. It should have self cleaning property.
5. It should retain a minimum quantity of water consistent by providing deep water seal and large surface.
6. It should be fixed easily with the drain.
Seal in trap
The vertical distance between the inside lowest and inside highest point is called seal in trap or water seal. The efficiency of trap depends upon the depth of a water seal. Therefore deeper the seal in trap more efficient in the trap the depth varies from 2.5 to 10 cm.
Causes of breaking seal
The following are the cause of breaking seal
1. The seal may break due to faulty joint.
2. The seal may break due to any crack in bottom of seal.
3. The seal may break due to certain of partial vaccum in the sewer fittings.
4. The seal may break due to increase in the pressure of sewer gases. The increase in pressure may occur due to blockage.
5. The seal may break if it is not used for a long time.
Precautions for preventing breaking of seal
1.The portion between the soil pipe and the trap must be connected to the vent pipe in order to avoid the breaking of seal to creation of partial vaccume.
2. The anti-siphonage pipe should be used in building.
Classification of traps
The traps are classified in the following
a) According to the shape of the trap
b) According to the particular use of the trap
c) According to the shape of trap
1. ‘P’ trap
2. ‘Q’ trap
3. ‘S’ trap
‘P’ trap
The trap having the shape of latter P called ‘P’ trap. In this case the leg of the trap are at right angle to each other.
‘Q’ trap
The trap having the shape of latter as showing in fig. In this case the legs of trap meet at an angle other than right angle.
‘S’ trap
The trap having the shape of latter is called ‘S’ trap. In this case the edges are parallel to each other.
According to particular use of trap
a) Floor traps
b) Gully traps
c) Intercepting traps
d) Crease traps
Floor trap
The traps which are used for admitting surface wash or waste water from the floors of bath and kitchen are called floor traps. This traps is placed in bath rooms, kitchen and sinks etc. and the starting point of waste water flow. It is covered at the top with an iron grating so as to prevent the entry of solid matter in it the cover providing on the top can be removed for cleaning the nahani trap.
Gully trap
The trap which is used to receive waste water from sinks, baths, wash basins and rain water is called as gully trap. It is usually used placed near the external face of wallet a distance of about 450 mm. It is generally made with stoneware with iron grating at the top. A water seal about 20 to 60 mm is provided into the gully trap. It consist of an opening at the top called as cleaning eye or rodding arm with a light fitting plug.
Intercepting trap
The trap which is provided at the junction of house drain and sewer is called intercepting trap. It is provided in the last man hole of the building. It’s main function to prevent the entry of foul gases from sewer into the building and as such it is called as interceptor or disconnecting trap.
Grease trap
The trap provided in the plumbing system for remaining grease oil and gasoline called grease trap. A grease trap consist of a smaller container with an inlet placed just near the tap. An outlet is provided through bend pipe having its lower end near the floor.
Plumbing system
The plumbing system is two types.
1. One pipe system
2. Two pipe system
One pipe system
The collection of water from wash basin, bath and kitchen, water closets and urinals into main pipe for disposal of drainage system is called one pipe system. The following point should be kept in mind while adopting this system.
Diagram
Diagram
a) The traps should be provided with a deep water seal of 75 mm depth.
b) The diameter of the vent pipe should not be less than 50 mm.
c) The joints of the waste pipe should be air tight.
d) The fall of the waste pipe in the direction of the flow should be continuous and gradual. The slope of waste pipe should be l in 20 to l in 48
Two pipe system
The collection of waste from closets and urinals in one pipe and waste from bath kitchen etc. in an other pipe is called two pipes system. The soil pipe and waste pipe are provided with separate ventilation on pipe. The following point should be noted.
Diagram
Diagram
1. Use of building
2. Location of building
3. Availability of funds
Maintainance of building
1. The maintainance problem become easy if the points discussed earlier and kept in mind while planning the drainage system.
2. The entire system should be cleaned once in a month.
3. The waste matter should not be thrown such that it should joint to the sewer.
4. The partical of sand, grit etc. should be collected separately and should not be allowed to move along with the sullage water.
5. Phenyl or any such approved disinfectants should be used regularly to maintain good sanitary conditions.
Testing of building drainage
The following test are commonly employed for testing drains and pipes
1. Air test
2. Coloured water test
3. Hydraulic test
4. Smell test
5. Smoke test
Air test
In this test air is forced in a selected section after plugging the ends then the soap solution is applied. If there is any leaked joint then bubbles will form moves it which can be noticed.
Coloured water test
If coloured water test is added from one side then it will come through the leak joints if any.
Hydraulic test
It is also known as water test
Smell test
In this case first air is filled with some smelling gas. Then it is allowed to pass through the drainage pipe. If there is any leaky joint then the same can be detected by smelling.
Smoke test
Smoke test is passed through the smoke will come out of the leaky. If any joint is found defective should be repaired immediately
Pipe fitting for building drainage
Diagram
Dome
It is use to out going of gases creating due to humen excreta and gases from the soil pipe.
