Plumbing for Building Drainage: Systems and Operations | Sanitary Engineering

In this article we will discuss about:- 1. System of Plumbing 2. Plumbing Operations 3. Safety and Precautions.

System of Plumbing:

Following are the main systems of plumbing for the building drainage:

(a) Two-Pipe System:

This is the most common system used in India. This method provides an ideal solution, where it is not possible to fix the fixture closely. Fig. 24.21 illustrates the line diagram of this system.

In this system, two pipes are provided. One pipe collects the foul soil and lavatory wastes, whereas the second pipe collects the unfoul water from kitchen, bathrooms, house washings, rain water etc. The soil pipes (pipes carrying the soil waste) are directly connected to the drain, whereas the waste pipes (pipes carrying unfoul water) are connected through the trapped gully. All the traps used in this system are fully ventilated.

(b) One-Pipe System:

In this system only one main pipe is provided which collects both the foul soil waste as well as unfoul waste from the buildings. The main pipe is directly connected to the drainage system. If this system is provided in multi-storeyed buildings the lavatory blocks of various floors are so placed one over the other, so that the waste water discharged from the different units can be carried through short branch drains. Fig. 24.22 shows this system by means of line diagram.

All the traps of the W.C., basins sinks, etc. are fully ventilated and connected to the ventilation pipe. But all gully traps and waste pipes are completely dispensed with.

(c) Single-Stack System:

Fig. 24.23 illustrates this system. This is similar to single pipe system, the only difference being that no ventilation is provided even in the traps too.

(d) Single-Stack Partially Ventilated System:

This system is in between the one pipe and single-stack system. In this system only one pipe is provided to collect all types of waste water foul as well as unfoul. A relief vent pipe is provided for ventilating only the water closet-traps. Fig. 24.24 shows this system.

Now a days in modern multi-storeyed buildings one pipe system is becoming popular due to its low cost. C.B.R.I. Roorkee, after doing extensive research on this system, has recommended it in modern buildings.

An analysis of this system showed that the flow from the applicant to the stack through branch is momentarily halted at the sharp change of flow of direction. Sometimes a plug of water is formed immediately at the junction, which depends upon the rate of change of discharge and the size of branch.

This gives rise to unequal pressures at the seals, for the lower floors of the building and sometimes this breaks the water seals of the sanitary appliances. C.B.R.I, has recommended the use of aerator and deaerator in the stack to increase its capacity.

The function of the aerator is to prevent the formation of the plugs of water in the vertical stack and to make a mixture of water and air of low specific gravity. The aerators are provided at every floor.

(a) For supply of water to various sanitary fittings.

(b) For collection of waste water from the sanitary fittings.

(c) For collection of rain water from the roofs, house and courtyard washings.

The fixing of sanitary appliances in the walls, floor and other places and their connected pipe works are to be done carefully for their proper functioning.

Deaerators are provided at the foot of the stack to separate air and water to avoid excessive back pressure. Studies carried out by C.B.R.I. revealed that 100 mm dia. Stack with these fittings can be safely used up to 15 storeys, whereas a single stack system without these fittings can be used only up to 5 storeys.

The two pipe system is costly as it requires much labour and material with antisyphonage pipe, as compared with single stack system of plumbing. No antisyphonage pipe is required. The single stack system is becoming popular in the modern building construction. The tests done by C.B.R.I. on 5 storeyed building shows that there was no break of water seals.

As it is the common practice in India to discharge the waste water from the sinks and wash basin to the floor trap, therefore, sanitary appliance carrying unfoul waste water do not require deeper seals. 100 mm dia stack with two appliances at each floor can be safely used up to 5 storeyed building.

Plumbing Operations:

Following are the main plumbing operations:

(i) Fixing of brackets, hooks, etc. for fixing of sanitary fittings.

(ii) Fixing of sanitary appliances or fittings.

(iii) Laying of water pipe line.

(iv) Giving connections to various sanitary fittings.

(v) Laying of pipe lines for collection of waste water.

(i) Fixing of Brackets:

The brackets of wash basins, sinks, flushing cisterns, geysers, etc., are fixed in the walls at proper positions. Generally, the holes are made in the walls and after placing the brackets at proper level and positions in the holes, they are filled with rich 1: 4 cement sand mortar.

The line of the water pipe is marked on the wall or floor at the proper place and the pipe hooks are inserted in the walls with their ends sufficiently projected from the walls for placing of water pipes in proper position.

(ii) Fixing of Sanitary Appliances or Fittings:

The sanitary fitting are fixed on the brackets, when the joints of the brackets with walls are cured. For fixing of Indian type water closet first of all the bottom trap is fixed in position and connected with the outlet earthenware or A.C. pipe. The W.C. seat is fixed over the trap. The joint between the seat and the trap is filled with rich cement mortar properly.

Now the space around the trap and seat is filled with lime concrete up to required height, over which the flooring is made. The foot rests are fixed on the floor at proper place. The flushing type connections are made to the seat from the flushing cistern before laying of door.

The English W.C. seat is laid and fixed on the floor, but its trap and the outlet pipe is laid before laying of floor. Therefore care should be taken while fixing these types of W.C.

Urinals are fixed on the wooden pegs fixed in the walls at proper heights. These are fixed by means of screws to the pegs.

The high level flushing cisterns are fixed on the steel brackets, whereas the lo-v down cisterns are fixed on wooden pegs or brackets as the case may be.

The bath tub is directly laid on floor. Sometimes it is embedded in masonry work while glazed tiles or terrazzo finish is provided over it.

Kitchen sinks, sinks and geysers are fixed on the steel brackets fixed in the walls. The kitchen sink drain board is supported on one side on the sink and on the other side on the steel bracket.

All the miscellaneous fittings such as mirror, tooth brush holder, soap tray, towel hooks, sanitary paper reel towel rod, etc. are all on the wooden pegs provided at the proper height and place.

(iii) Laying of Water Pipe Line:

Before laying the pipe line, all the lengths of the pipes are cut to sizes, screwed at both the ends. Care should be taken in measuring the exact length of the pipe lines, because if shorter or longer lengths are cut they will not properly fit in position allowance for the sockets, valves tee, elbows, cross, etc. should be made.

The pipe laying work should be started from one side. All the joints should be made watertight by wrapping jute yarn soaked in white lead paint in the threads of the joint. After laying the pipe line it should be held in position by means of pipe hooks embedded in the walls. At -every floor one union should be provided.

(iv) Connection to the Sanitary Appliances:

After laying the pipe line, the connections to the various sanitary appliances are given. In case of wash basins, kitchen sinks, urinals etc. Lead or plastic connectors are used for giving connections. All the joints should be made water-tight by wrapping jute yarn soaked in white lead paint.

(v) Laying of Pipe Lines for Collection of Waste Water:

AC. or stone ware or earthen ware pipes are used for the collection of waste water. Care should be taken to take the foul water i.e., from water closets and urinals in a separate pipe line. The unfoul water from wash­basins, kitchen sinks, bath tubs, bathroom, etc. is taken in separate set of pipe line, because soapy water may kill all the bacteria responsible for the treatment of sewage in the septic tanks. But now a days single stack system is also used in which all types of waste water is collected and taken in one set of pipe lines.

Figure 24.25 shows the method of doing plumbing work in two pipe systems. In this method foul water is taken in one set of pipe lines and the unfoul water is taken in another set of pipes.

Figure 24.26 shows the method of doing plumbing work in single-pipe system. In this method all types of waste water foul and unfoul is taken in the same of pipes.

Figure 24.27 shows the details of connection in case of single or one pipe system.

Laying of Rain Water Pipes:

The pipe laid to collect the rain water from the roof is known as ram water pipe. The rain water from the flat as well as sloppy roof is to be collected and brought on the ground level, from where it is allowed to flow in open drains.

Figure 24.28 shows the method of fixing rain water pipe for collecting rain water of flat roof, along with all the specials required at various places.

Fig. 24.29 shows the method of fixing rain water pipe for collection of rain water from sloppy roofs.

Safety and Precautions to be Taken While Doing Plumbing Work:

Following precautionary measures should be followed while doing plumbing work:

1. All the tools should be properly inspected for their proper working conditions.

2. Only standard material should be used in the plumbing work, because sub-standard materials may cause leakage in pipe lines, taps, etc.

3. Correct threading, the same which is on the specials should be done on the pipes.

4. All the joints should be made water-tight by wrapping jute thread and white lead paint in the threads, while screwing.

5. Over-screwing should not be done in any case; otherwise it may split or crack the parts of the fittings, socket, elbow, tee or cross, etc.

6. While measuring the length of pipes for cutting due allowance for the space of fittings should be made, otherwise the length of the pipes may be more or less.

7. All the pages should be fixed with their broader end inside the wall and smaller size in face of the wall.

8. Only the required size hole should be made in the wall for fixing of pegs, brackets, etc.

9. While fixing the pipe in the pipe-vice, it should not be over-tightened, otherwise it may also press the pipe and give more bend than desired.

10. While bending the pipes on the bending machines, care should be taken otherwise it may also press the pipe and give more bend than desired.

11. The cutting of the pipes should be done properly, it should be at right angle to the axis of the pipe.

12. The pipes should be fixed with the pipe-hooks at proper place. These hooks should be driven in the masonry joints.

13. In case of accidents first-aid facilities should be available.