Praise is presented only for ALLAH Almighty Disposer of all things. Peace and
blessings be upon beloved Prophet Muhammad leaflets bearing the revelation to
illuminate be universe, the companions, his family, all the scholars and lovers of Islam
throughout the world.
Thank to God that, I can complete the assignment on the end of chapter problem
about how to prevent loss water seal to be handed over to Mr. Huzaime b. Abd. Hadi
very well. By making this assignment I can add my knowledge.
Finally, we thank the lecturers who taught me, Mr. Huzaime b. Abdul Hadi has
been providing guidance and information on how to produce this work. Thank also to
friends who also give me lessons and share ideas and information.
The loss of a trap seal will usually result in foul and objectionable gases and
odours entering a building from the system of discharge pipework. These gases will at
least be a nuisance and in extreme cases create a health hazard to the occupants of
the building. It is for these reasons that much importance is placed upon retention of the
water seal in all trap.
Trap seal may be lost in several ways. Some reasons may be attributed to bad
system design or installation techniques. Others are more natural or the result or
particular cimcumstances which may cause the loss of water seal, the common
circumstances are self siphonage, induce siphonage, back pressure, capillary attraction,
wavering out, evaporation, momentum and leakage.
HOW TO PREVENT THE PROBLEM
1) Self Siphonage
This is caused by a moving plug or charge of water running out of a steep-sided
sanitary appliance such as a wash basin. The plug of water moves through the trap,
pushing the air on the outlet side of trap in front of it, thereby creating a partial vacuum
in the branch discharge pipe which causes siphonage to occur and loss of the trap seal.
The technical term for the partial vacuum or negative pressure zone is ‘hydraulic jump’
as ilustrated in Figure 1 and 2 Self siphonage. Self siphonage of a trap usually indicated
by an excessive amount of noise as the sanitary appliance discharge its final quantity of
Figure 1 Self siphonage.
Figure 2 Self siphonage.
Figure 3 Example of basin waste where self siphonage may occur.
How to prevent :
Self siphonage is usually prevented by one or more of the following:
1. By fitting a P trap to the sanitary appliance (thus avoiding vertical branch
2. Ensuring that the branch discharge pipe length and slope do not exceed
3. By fitting a ventilating or anti-siphon pipe adjacent to the trap outlet.
4. By fitting a larger diameter branch discharge pipe to the trap outlet.
5. By correct design of sanitary appliance.
6. By fitting a resealing or anti-siphon trap to the sanitary appliance.
2) Induce Siphonage
This is caused by the discharge of water waste from one sanitary appliance,
pulling or siphoning the seal of a trap of another appliance connected to the same
branch discharge pipe. This form of siphonage is most common in buildings where
ranges of appliances are fitted or where it is necessary to connect several appliances to
a common branch discharge pipe. The main causes of induced siphonange are poor
system design, inadequate pipe sizes or bad installation techniques.
Figure 4 Induced siphonage.
Figure 5 Induced siphonage.
Figure 6 Trap with induced siphonage.
How to prevent :
Some ventilation of the system may be required if induced siphonage is to be
3) Compression or Back Pressure
Compression of air at or near the base of a discharge pipe may occurs as shown
in Figure 7. As water flows down a vertical stacks it takes some air with it. As this water
changes direction at the base of the stack (from the outside of the vertical pipe to the
invert of the near-horizontal drain pipe) the pipe bore becomes momentarily full of
water, so preventing the free flow of air up and down the discharge stack.
Figure 7 Compression or Back Pressure
Figure 8 Example of back flow into bath.
How to prevent :
Under these conditions a hydraulic wave is formed and air at the base of the
stack is compressed by a water falling from above, thus creating air pressure in excess
of atmospheric pressure. This pressure will attempt to escape through any branch
discharge pipe connected in the compression zone, thus blowing the seal of the trap
and allowing foul air from inside the discharge pipework to enter the building. Often the
displaced water will run back into the trap to form a seal but continued blowing of the
seal will cause a noise nuisance and allow foul gases into the room where the appliance
is fitted. Compression and back pressure are prevented by not fitting small or sharp
radius bends or having branch discharge pipes connected near to the base of a
discharge stack. Correct practice is to fit large radius bends and to ensure inlet
connections are not made close to the base of the stack.
4) Capillary Attraction
Loss of seal by capillarity occurs when a piece of porous material such as
threads or string from a mop or dishcloth are deposited into the water seal and over the
outlet invert of a trap as shown in figure 9, this will most commonly happen to
appliances such as kitchen or cleaners sinks fitted with S pattern traps.
Figure 9 Capillary Attraction
How to prevent :
Capillarity is prevented by regular cleaning of the inside of the trap and branch
discharge pipe or by laying a loose mesh strainer into the waste fitting of the appliance
to catch and retain loose porous strands which may be contained in certain types of
5) Wavering Out
The effect of a high-velocity fluctuating wind passing over the top of an exposed
discharge stack ventilating pipe (see figure 10) will create varying air pressures and
draughts within the pipework system which may cause trap seals to fluctuate or waver,
resulting in loss of water from the seal.
Figure 10 Wavering Out
How to prevent :
Fluctuating, pressures caused by wind are best prevented by locating the vent
terminal position away from exposed locations and ensuring that a terminal grating is
fitted to all ventilating pipework.
This occurs usually in traps connected to sanitary appliances which are not used
regularly or where the ambient temperatures are relatively high. Evaporation is more
usual in the summer month when temperatures are higher or when buildings are left
empty or unattended due to holiday periods.
The most usual cause of lossof trap seal by momentum is when quantity of water
is quickly discharged into a gully or washdown WC pan and the discharging water
carries away the water forming the trap seal.
Trap occasionally loose their seals due to a leak on the fitting bellow water-seal
level. The leak may be due to a loose or badly jointed access bowl or cleaning eye or in
the case of soft materials, caused by impact resulting in fracture and damage to the trap
Expertise in need of repair leakage
The work to repair the leak involves two tasks that require expertise:
1. Determine the cause and location of the leak.
2. Techniques and rules of waterproof material installed correctly.
The material used is known as water-resistant material or material
Waterproofing. This water-resistant material widely available in the market with different
brand names depending on manufacturer and distributor of such materials. Use of
fishing gear, equipment and means of proof is installed will determine the quality of
water proof work.
How can happen release
Unwanted leakage occurs. However it can occur in places and at unexpected
times. Leaks are a form of defects in the building and it can be caused by several
1. Construction design.
2. Low Mutukerja during construction.
3. Durability of materials.
4. The influence of the environment.
5. Lack of maintenance activities.
6. The use of the building, misconduct and external pressures.
Must be corrected release
Leak repair is the need to premises / building:
1. Meet the real purpose of the premises / building constructed.
2. Extend the economic life of the premises / building.
3. Reduce the potential for damage to buildings or equipment which caused
disruption to building operations.
4. Maintain the market value.Maintain the aesthetic value.
5. Increase worker productivity.
6. Ensure the safety and comfort of residents.
7. Meet the legal requirements of the building.
In conclusion, to complete the task, I can find out about the loss of factors guard
with deep water in the trap again. There are self siphonage, induce siphonage, back
pressure, capillary attraction, wavering out, evaporation, momentum and leakage. In
addition, I can find out how to overcome them.