TRAPS AND MANHOLE

TRAPS & MANHOLE

ADITYA KUMAR BARN1AR1400

2ITMU.SOAD

TRAPS

TRAPS INTRODUCTION :-Traps are an integral part of a modern sanitary system, being designed to retain a small quantity of the waste water from the discharge of fitting to which they are attached as a barrier to prevent foul air entering the building as shown in Figure

Traps should be self-cleaning, that is to say , they should be designed so that their walls are scoured by the discharging water. One of the advantages of modern traps constructed of plastic materials is the ease with which they may be dismantled for cleaning.

Traps are defined as fittings at the end of soil pipes of waste pipes to prevent foul gases coming out of the soil pipe/ waste pipe.

The trap most commonly used with plumbing fixtures is the P-trap. The P-trap gets its name because of its general shape-that of the letter P.

Traps are required because they prevent sewer gases from entering a building and causing serious illness or death.

The term Trap Seal refers to the water being held in the bent portion of a fixture trap. The trap seal forms a seal against the passage of sewer gases through the trap and into the building.

Building (House) traps shall be provided with a cleanout and a relief vent or fresh air intake on the inlet side of the trap.

Relief vents or fresh air intake shall be carried above grade and shall be terminated in a screened outlet located outside the building.

The size of the relief vent or fresh aid intake shall not be less than one-half the diameter of the drain to which the relief vent or air intake connects.

Building traps:- Building (house) traps shall be prohibited, except where local

conditions necessitate such traps. Building traps shall be provided with a cleanout

and a relief vent or fresh air intake on the inlet side of the trap. The size of the relief vent or fresh air intake shall not be less than

one-halfthe diameter of the drain to which the relief vent or air intake connects. Such relief vent or fresh air intake shall be carried above grade and shall be terminated in a screened outlet locatedoutside the building.

Traps And Pipes and other components of house Drainage System:-

o Following are the main components of House drainage system.

o Traps: Good Traps should have following Qualities:o Should provide enough water seal ( around 50 mm) with

large surface area.o Interiors surface should be smooth so that the flow is not

obstructed which enables self cleansing.o An assess door should be provided for cleaning the trap.o It should be made of non- adsorbent material.

Classification of Traps• Depending upon the shapes the traps are classified as:• P-Trap• Q-Trap• S-Trap• Above three types of traps are shown in the following

figures.• The depth of a Trap Seal would depend upon the

usage of a pipe. The trap seal varies from 25 to 75 mm deep.

P, Q and S Traps

P Trap

Q Trap

S Trap

Nahni Trap

Gully Trap

Intercepting Traps

Advantage of Intercepting Traps•Foul Gases of larger municipal sewers are prevented from entering house drainage system.•Harmful pathogens are not entered in house drains.•Well designed and contructed interceptors can quickly remove foul matter of house drain to muncipal sewers.

Loss of Trap Seals

caused

• Evaporation• Capillary action• Momentum• Leakage• Wavering out• Compression or back

pressure• Induced siphonage• Self siphonage

If a trap seal loss, smells from the sanitary appliances would enter the building. Therefore the water seal in the trap must be maintained under all circumstances.

1) Evaporation

When trap is not being used, the rate of water evaporation depends upon the relative humidity of the air in the room. The rate is approximately 2.55 mm per week, so a 25 mm seal would last for 10 week. See Fig.

Fig.Evaporation occur when trap not being used

2) Capillary attraction

Is another rare occurrence which happens in ‘S’ trap when a piece of porous material being caught over the bend of a trap absorbs water and deposits it down the waste discharge pipe. See Fig.

Fig. Capillary attraction

3) MomentumThis is caused by a sudden discharge of water from a bucket. Due to velocity water is discharged and it shoots around the trap bend and goes down the waste pipe, leaving no seal.

4) Leakage It is caused by a fault in the trap or plumbing installation and water on the floor would be apparent.

5) Wavering out This is caused by the effect of the wind which passes over the top of the ventilation pipe and thus causes pressure fluctuations. See Fig.

6) Compression or back pressure This occurs in high rise buildings. When water is discharged down to the main discharge stack, air is compressed at the base of the stack. A waste pipe connected to the stack in the pressure zone may have the seal of the trap lost by the compressed air forcing out the water. Detergent foam increases the risk of compression. See Figure 3.9 .

7) Induced siphonageThis is caused by discharge of water from another sanitary appliance connected to the same discharge pipe. In either a vertical or horizontal main waste pipe, as water flows down the pipe and passes the branch pipe connected to it, it draws air from it, thus creating a partial vacuum and subsequently siphonage of the trap takes place. See Fig.

8) Self siphonage This is caused by appliances such as wash basins and other small appliances, due to their curved shape, and is caused by a moving plug of water in the waste pipe. A partial vacuum is created at the outlet of the trap, thus causing siphonage action takes place. See Fig.

MANHOLE

34 Foot Structural Liner – One of 43 Manholes –

INTRODUCTIONA manhole (alternatively utility hole, cable chamber, maintenance hole, inspection chamber, access chamber, sewer hole or confined space) is the top opening to an underground utility vault used to house an access point for making connections, inspection, valve adjustments or performing maintenance on underground and buried public utility and other services including sewers, telephone , electricity, storm drains, district heating and gas.

USES:-Manhole closings are protected by a

manhole cover, a flat plug designed to prevent accidental or unauthorized access to the manhole.

Those plugs are traditionally made of metal, but may be constructed from precast concrete, glass reinforced plastic or other composite material (especially in Europe, or where cover theft is of concern).

The access openings are usually circular in shape to prevent accidental fall of the cover into the hole

Manholes are generally found in urban areas, in streets and occasionally under sidewalks. In rural and undeveloped areas, services such as telephone and electricity are usually carried on utility poles or even pylons rather than underground.

Manholes are usually outfitted with metal, polypropylene, or fiberglass steps installed in the inner side of the wall to allow easy descent into the utility space. Because of legislation restricting acceptable manual handling weights, Europe has seen a move toward lighter weight composite manhole cover materials, which also have the benefits of greater slip resistance and electrical insulating properties

PRECAUTIONS TO BE TAKEN WHILE INSTALLING:-

Do not cantilever the frame:RCC Frame is not built to take on tensile loads. However, it is able to take sufficient compressive loads. Therefore the frame should be fully supported on the support structure, i.e., Chamber walls or Slab. The frame may fail if it is not fully supported.

Please ensure that the structure on which the Frame is placed is able to take the load which is expected from the RCC manhole cover: Please note that loads acting on the RCC Manhole Cover and Frame are transferred to the chamber walls or slab on which the frame is placed. Therefore, the support structure (Chamber wall or Slab) should be designed and built to carry the loads. Not doing so may result in failure of the support structure. In some cases this gives an impression that the cover has failed while in reality the support structure buckles or collapses under the load.

Never make the Frame a part of the Slab: In some cases the workmen while making arrangements for the Frame, casts the frame along with the slab (refer to Figure 1). In doing so the thickness of the slab on which the frame is resting is very thin. This will result in failure of the structure as the slab on which the frames rests is not able to bear the load expected of the RCC Cover.

Prepare the top of the brick manhole by concrete so as to make it leveled:Often when workmen are constructing a conical manhole from brick, they have a tendency to keep the RCC frame on top of the brick manhole while leaving a big gap between the top surface of the brick manhole and the bottom surface of the RCC frame (refer to Figure 2). They are working with the assumption that eventually the gap will be filled by mortar. In reality, this gap is never filled properly because of the inward slope of the inside surface of the brick manhole. As a result, the concrete filled in the gap will never have perfect contact with the bottom of the RCC Frame. This may result in sheer failure of the frame seating because the frame is not designed to carry tensile loads.

SECTION:-

Manhole Rehabilitation:

• Epoxy Coating/ Lining• Poly-Urea Coating/ Lining• Urethane Coating Lining• Calcium Aluminate Mortar• Cured in Place Liners• Fiberglass Inserts• HDPE Manhole Inserts• Cementitious Lining• Polymer Mortars

ADVANTAGES:-EFFECTIVE WASTEWATER TRANSPORTATION AT MINIMUM DEPTH,

MINIMISING THE EXCAVATION FOR THE PIPING SYSTEMGRAVITY FREE; INDEPENDENT FROM LAND TOPOGRAPHYLOW COST COMPARED TO A CONVENTIONAL GRAVITY SEWER PIPE SIZE AND DEPTH REQUIREMENTS ARE REDUCED AND MANY SMALL

PUMPS ARE CHEAPER THAN SOME LARGE –CAPICITY LIFT STATIONSREQUIRED LITTLE WATER ONLY FOR TRANSPORTING THE EXCRETAFOULE GASES CANN’T EFFECT THE ENVIRONMENT.EASILY CARRY SEWER WESTE THTOURH PIPELINE

DISADVANTAGES:-

NEED EXPERT DESIGN, HIGH CAPITAL COSTSNEEDS A PERMANENT CLINING MANAGEMENT.A PROPER RECYCLING OF NUTRIENTS AND ENERGY BECOMES

DIFFICULT, BECAUSE ALL KINDS OF WASTERS ARE MIXEDUNSUTIABILITY FOR SELF HELP,REQUIRES SKILLED ENGINNEERS AND

OPERATORSIT IS STILL A FLUSHING SYSTEM WHICH TRANSPORTED WASTWATER

AWAY . IT THERE IS NO TRETMENT PLANT AND AN UNPROFESSIONAL DISCHARGE IT CAN CONTIMINATE THE ENVIRONMENT

LEKAGES MAY LEAD TO CONTAMINATIONS

Case study