During construction, while discussing the house drainage system or drainage plan with Engineer or Plumber, often we hear some technical terms about which we don’t know. Here we have listed such important terms which are very important and used in the house drainage system.
1) Soil Pipe: This term is used to indicate the pipe which carries discharge from urinals and water closets only. Thus pipe is usually vertical and use to collect sewage from urinals and W.C.’s fitted on different floors of a multi-storeyed building. It may be made of PVC, Cast Iron or Earthenware.
2) Waste pipe: This term is used to indicate the pipe which carries discharges from house fittings other than urinals and W.C.’s like bathroom, kitchen, sink, wash basin etc.
3) Vent pipe: It main function is the ventilation of the sewers and septic tanks. It should be open at top and bottom.
4) Cowl: The top of vent pipe is provided with cowl so that the birds may not build their nests. Cowls are provided with slit of narrow openings.
5) Ventilating Pipe: The drain intended to carry waste water and sewage from a house should be provided with at least one ventilating pipe situated as near as practicable to the house and as far as possible from the point at which the drain empties into the sewer or other carrier. Such ventilating pipe should be carried up vertically to such a high that it will not cause nuisance.
6) Inspection chamber: It is a masonry chamber constructed on the house drain to provide access for cleaning, inspection and repairs. Drainage pipes at inspection chambers are made rectangular in shape and covered with precast concrete slab. The floor of the chamber is made of cement concrete floor, having steep slope towards the drain. It is provided at regular intervals of 3m or more in straight and at every bend. The size of the chamber depends on the depth below ground and number of branch connections. Upto 900mm depth its size may be 600mm x 750mm.
7) Anti-syphonage pipe: The main function of the anti-syphonage pipe is to prevent breaking of water seal of the traps. If several lavatory blocks situated on different storeys are discharging into a common soil pipe, anti-syphonage pipe is always essential. Suppose W.C. at second floor has been flushed. The flush water goes down the soil pipe with a rush, thus creating partial vacuum in the soil pipe. This causes sucking of water from water seals of traps fitted in other storeys. This may lead to breakage of water seal. Anti-syphonage pipe keeps all the traps well ventilated and avoids possibility of seal break.
8) Fresh air inlet: The last manhole which connects the house drain with public sewer is provided with an inlet of fresh air. This fresh air inlet dilutes the sewage gases. Fresh air inlet pipe is kept at about 2m height from the ground level and it is provided with mica flap valve at its top. This valve opens inside only and thus admits fresh air and prevents escape of foul gases through it.
9) Flushing cistern: Flushing cistern is a device which is used for flushing water closets and urinals. It consists of a casing box in which a float connected to inlet, a flushing lever and flush pipes. In earlier days they were made from Cast iron but now they have been replaced by PVC flushing cisterns. Now a day’s concealed flushing cisterns are being used.