A fixture trap is a device scientifically designed to
prevent the backflow of gases into the outlet of the
Trap seal – the column of water that is retained
between the overflow & dip of the trap. Also known
as “Water Seal”.
Water sealed traps are classified as:
Permissible Traps and as Objectionable Traps
The Permissible Type of Traps are:
2. The Drum Trap
Attributed to its form that is in some manner as the
neck of the goose. P-trap is used to provide a
mechanical barrier against passage of noxious air form
the septic tank or main sewer line.
The Water-Sealed P-Traps Classifications:
1. The common seal P-Trap
2. Deep Seal P-Trap
What is a common seal P-trap?
A common seal P-Trap is used for fixtures that are
subjected to normal conditions. This trap has 5 cm
deep water seal.
What is a Deep-Seal P-Trap?
A deep seal P-Trap has from 7.5 – 10 cm water seal
content. It is purposely designed for situations such
a. Extreme heat condition in the area.
b. Increase/decrease in atmospheric pressure.
c. Circumstances where total ventilation is
Re-sealing is the term used to the scientific principle
that water at rest tent o seek a level & maintain it.
One advantage of the Deep Seal over the Common
Seal traps is its greater re-sealing quality.
Common P-Trap operated
The P-Trap is the most common and practical shape
available in various sizes from 32 - 150 mm in
diameter. These are suitable for fixtures such as:
4. Drinking Fountain
5. Shower Bath with less amount of discharge.
Some other types of Permissible Traps:
1. Stand Trap
5. Extra Heavy Type
2. Brass Trap
3. High Hub Trap
4. Low Hub Trap
6. Sink or Lavatory Type
The objectionable traps which are
found defective includes:
1. The full size S and the ¾ S Traps.
2. The Bag Traps.
3. Mechanically Sealed Traps.
4. Light metal partition traps.
The National Plumbing Code on
P-Trap Installation provides that:
All traps shall be self cleaning.
P-Trap should be installed as near the fixture as practical.
Short vertical leg eliminate high velocity of water discharge
which create siphonage.
The P-Trap should be installed within 60 cm of the fixture and
accessible for cleaning through the bottom opening closed by a plug.
All traps are subject to stoppage, hence, should be provided with
cleanout or be designed that could be disassembled with little
Long run of horizontal pipe called running trap could be used only
near the drain of the floor area or yard and not provided with handhole cleanout.
Overflow pipe from fixture should be connected into the inlet side of
The dip portion of the trap should be as short as possible to avoid
retarded flow of water. Likewise, the horizontal leg connection to the
waste pipe must be short for effective ventilation.
7. That, each fixture trap shall have its own trap. The
following are exceptions to the rule:
a. Two laundry trays and a kitchen sink connected to a
b. Not more than 3 laundry tray using one trap and
c. Three lavatories on a single trap.
The drum trap derived its name from
its form and size being large in diameter.
1. For fixture that are set on the floor such as bath tubs,
foot & sitz bath, etc.
2. For fixtures that discharges substantial amount of
water wherein trap-seal loss is more prevalent.
3. Used as terminal for soda fountain, bar wastes and
any type of indirect waste.
4. Designed in two types
(a. 100 x 125 mm, b. 100 x 200mm)
Advantages & Disadvantages if
1. Greater amount of water may pass through it in a shorter
interval without danger of trap seal loss.
2. It has a higher re-sealing quality than the P-trap.
It is large and cumbersome
It is unsightly if the installation is exposed.
The cleanout mechanism is above the water seal.
To clean the drum trap need lubricant and a fiber washer
in the joint between the cove and the body of the trap.
The National Pluming
Code has regulated the
minimum diameter of
traps and drain sizes to
be installed depending
upon the class of user for
which the installation is
Classifications of fixtures to be installed:
1. Class 1 – For Private Use applied to fixtures in
residences, apartment and private bathroom of
hotels and etc.
2. Class 2 – For Semi-Public Use applied to fixture in
office buildings, factories, dormitories and etc.
3. Class 3 – For Public Use such as
schools, gymnasium, hotels, railroad and bus
terminals, public CR’s and etc.
The House Trap
House Trap is a device installed in the house drain
that act as barrier to prevent the gasses from the
public sewer line or septic tank in circulating
through the plumbing system of the house.
Floor Drain Installation
A Floor Drain is a receptacle intended to receive
water from the floor & convey into the plumbing
system. Floor drain is usually installed on:
Near the heating equipment
Below the kitchen sink
2. Every floor drain should be supplied with running
water from a fixture nearby.
3. The 75 mm (3”) P-Trap is recommended for floor
drain. It should be installed not more than 30cm
below the floor line.
4. The trap should be Deep Seal type.
5. The trap may be of low inlet hub pattern.
It is a device installed on plumbing system serving
kitchen of hotels, dining rooms, clubhouses and
Installation of Grease Trap
1. The grease trap should be installed as close to the
fixtures as possible.
2. More than one fixture can discharge into the same
trap provided that the trap has sufficient pipe size
and the waste pipe is not very long.
3. Earth-Cooled Grease Trap is used on large
installation and is most desirable type.
4. The basin width should be not less that 60cm long.
The minimum depth of concrete grease trap should not be less than 120 cm below the outlet
7. The size of the grease trap is measured through the amount of fixture unit discharge.
The Sovent System
Is a recent development in drainage installation
which is suitable for tall buildings. It almost
completely eliminate the vent stack and other forms
of ventilation with the same effectiveness.
Introduced in 1962 by Fritz Sommer of
Switzerland, it was tested on a 10 storey drainage
tower which has resulted in a satisfactory
First used in the US in 1968 at the Uniment
apartment in Richmond, Ca.
The two line system
Often referred to as
DWV, this system has
been proven efficient
plumbing system and
universally accepted for
However, the incorporation of the vent pipe in the plumbing system
although promoting efficiency in the installation services, has also brought
1. The routing and re-routing of the various kinds of
2. Additional cost for materials and labor.
3. Space requirements.
In order to address this problems, a new concept of
Plumbing System called Sovent System was
Mechanics of the sovent system
1. A large amount of waste and sewage discharges
form the fixtures could form like a slug that presses
the air downward the pipe and create two kinds of
forces such as pressure and suctions.
2. The downward force, called plus pressure create back
flow of water seal in the P-Trap of lower
fixtures, while the suction force called minus pressure
create siphonage inside the pipe pulling down the
water seal of the fixtures in the upper floor.
3. The Sovent function is to change the solid nature of
the effluent by scattering them into drops or small
blobs to fall like liquid in a shower.
4. Although the effluent rarely fills the soil pipe
completely, still it has the action of a plunger.
5. In a single stack Sovent System vent piping is not
6. The Sovent action of reducing the positive and
negative atmospheric pressure is done at each floor
where the aeraor is installed.
The effluent that was already
aerated falling down from
the upper floor is diverted in
the soil stack at each lower
8. The areator spatters or
scatter the effluent in drops
or small blobs wherin they
are mixed with the air
forming a rarefied mixture of
air and liquid.
9. At the bottom portion of the
single stack, the aerated
effluent is compacted.
10. The deaerator consist of an
air separation chamber with
and internal nose piece, a
stack inlet, a pressure relief
outlet at the top and an stack
outlet at the bottom.
Materials and Design
Copper was the original material used for Sovent
systems. This is attributed for its proven record of
quick, trouble-free installation.
Copper is also the material used for the Aerator and
The aerator is used as a terminal of the soil branch in
each floor of a building while the deaerator is
installed at the bottom portion of the soil.