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Drainage system

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Drainage system

  1. 1. Building Services DRAINAGE SYSTEM
  2. 2. DRAINAGE SYSTEM basically refers to All the piping within the private and public premises which conveys sewage, rainwater and other liquid waste to a point of disposal. A drainage system does not include the mains of public sewer systems or a private or a public sewage treatment or disposal plant. STACK A general term used for any vertical line of soil, waste or vent piping. SOIL PIPE A pipe that conveys the discharge of Black water (liquids containing fecal matter) WASTE PIPE A pipe that conveys the disvharge of only Grey Water ( liquid waste free of fecal matter. ) A waste pipe is generally smaller than a soil pipe because of the nature of matter being discharged into the system. BRANCH Any part of the piping system other than the main, riser or stack. BUILDING/HOUSE DRAIN That part of the lowest horizontal piping of a plumbing system which receives the discharge from soil, waste and other drainage pipes inside a building and conveys it to the building sewer/house sewer.
  3. 3. BUILDING/HOUSE SEWER That part of the drainage system that extends from the end of the building drain and conveys its discharge to the public sewer, private sewer, individual sewage disposal system, or other appropriate point of disposal.
  4. 4. SOIL STACK
  5. 5. Parts of a Drainage System „ ESSENTIAL COMPONENTS: – House Sewer – House Drain – House Trap – Fresh-air inlet – Soil and Waste Stacks – Fixture Branches – Traps – Vents „ SPECIAL DEVICES: – Interceptors – Sumps and Ejectors – Backwater Valves – Roof and Floor Drains House Sewer – It extends from the public sewer to the private sewage-disposal tank to the wall of the structure and is entirely outside the building - Plastic pipe –10’ to 20’ long – 12” deep with concrete pavement – 18” deep without concrete covering – Slope at 1/8” or ¼” to the foot
  6. 6. ESSENTIAL COMPONENTS OF DRAINAGE SYSTEM
  7. 7. House Drain – The horizontal main into which the vertical soil and waste stacks discharge. It connects directly to the house sewer. – Sanitary drain – Leader drain • Copper • Plastic • Extra heavy cast-iron – Slope at 1/8” or ¼” per foot – A cleanout at the cellar/basement wall is recommended to clear obstructions – A cleanout at the foot of each waste and soil stack should be installed Fresh-air inlet – It is intended to admit fresh air to the drainage system so that there will be a free circulation without compression throughout the house drain and stacks discharging above the roof – A necessary adjunct to the house trap
  8. 8. Soil and Waste Stacks – The soil and waste stacks collect the sewage from the fixtures through their branches. • Should rest solidly at the bottom on masonry piers or heavy posts • The upper ends should extend through the roof for ventilation • Made of heavy cast-iron, copper, plastic • Supported at intervals of 10’ with stout wall hangers or brackets or on beams • Min 4” Ø 1’ below the roof • It should be straight free of bends and turns
  9. 9. Fixture Branches – Connect the fixtures with the stacks – Waste or soil branches are connected to the trap of each fixture – 1/8” – ½” per foot – Horizontal branch should not be more than 5’ (from the vertical inlet of the trap to the vent opening – Cast-iron, plastic, copper or galvanized steel
  10. 10. Traps – Traps catches water after each discharge from a fixture so as not to allow unpleasant ad obnoxious gases in a sanitary drainage system to escape through the fixture – All fixtures are to be provided with its own trap except for three laundry and kitchen sinks connected to a single trap
  11. 11. – Trap seal must have a min depth of 2” and max of 4” depth – Placed within 2’ of the fixture accessible for cleaning through its bottom with a plug – Made of steel, cast-iron, copper, plastic and brass except those in urinals and water closets which are made of vitreous china cast integrally with the fixture
  12. 12. Vents – Vents are the extension of soil and waste stacks through the roof and a system of pipes largely paralleling the drainage system for the admission of air and discharging of gases.
  13. 13. SPECIAL DEVICES IN DRAINAGE SYSTEM
  14. 14. Interceptors – device designed and installed so as to separate and retain deleterious, hazardous, or undesirable matter from normal waste and permit normal sewage or liquid waste to discharge into the disposal terminal by gravity
  15. 15. Sump and Ejectors – A sump is a tank or a pit which receives sewage or liquid waste, located below the normal grade of the gravity system and must be emptied by a mechanical means – Sewage ejectors may be motor-driven centrifugal pumps or they may be operated by compressed air. Ejector pump for submersible system Ejector for Vertical lift submerge pump
  16. 16. Backwater valves/check valve – A backwater valve closes to prevent reverse flow from a sewer to low facilities when there is a heavy drainage load for short periods that can cause building up and over flow of wastes. Roof Drain – Is a receptacle designed to collect surface or rain water from an open area and discharge to a catch basin Floor Drain – Is any pipe which carries water or waterborne wastes in a building drainage system
  17. 17. Sizing rain water piping Local regulations on the disposal of rain or storm water are apt to vary. Some places permit this water to run off into the septic tank or public or private sewer; others insist that it be drained into a dry well. Regardless of which rule prevails, it is recommended that rain water be kept separate from sewage and that a separate pipe be used to connect the drained area with the disposal area. If this is done, the rain-water drainage piping can be a smaller, more economical size, and the danger of flooding the sewage system during a cloudburst or thunder shower is eliminated. Storm-water piping size is determined by the area drained in horizontal projection, that is, the flat area in square feet on which rain may fall. Measurements of roof and other such areas may be estimated, but in doubtful cases the larger of two possible pipe sizes should be used. Sizing house drain The size of pipe to be used in a house drain is determined by the number of units drained by it. Proper diameters are: for 2 units, 1 1/2"; for 9 units, 2"; for 25 units, 2 1/2". The size of any stack, house drain, or sewer must be, however, at least the size of the largest branch connected to it. The minimum size of a house drain receiving the discharge from a water closet should be 4" in diameter, and this pipe should continue full size to the vertical stacks receiving the discharge of water closets. Even without any water closets discharging into a system, the drainage system should have at least one 3" diameter stack extended full size through the roof.

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