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PLANNING the WATER DISTRIBUTION The system must provide adequate supply of water, with
adequate pressure up to the extremities of the system. The safety and quality of water should not be impaired by
defects in the system.
It should be provided with sufficient valves and blow-offs to
allow repair work without undue interruption of service tosome areas, and to allow flushing of the system.
There should be no unprotected open reservoir, or cross
connection with inferior water systems to enter the
distribution system. The water system should be tight against leakage.
The main and branches connection should not be submerged
in surface water, or subjected to any source of
contamination.
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PLANNING the WATER DISTRIBUTION The water system design shall afford effective circulation of
water with minimum number of dead end mains. The system shall be guarded against contamination in any
parts of it resulting from repair works, replacement orextension of the mains.
When new mains are installed, or old mains repaired, theyshould be filled with strong chlorine solution of 40- to60mg/L for at least 24 hours, and then flushed with watersupplied normally from the mains.
As much as possible, water main should be laid above the
elevation of concrete sanitary sewers, or crossover points,and at least 3 meters horizontally from such sanitary sewerwhen they are parallel. Should this be impossible for somereasons, the sewer main must be encased in concrete.
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TYPICAL WATER DISTRIBUTION SYSTEM
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CLASSIFICATION of WATER DISTRIBUTIONPublic water distribution is classified into:
Direct Pressure Distribution A direct-pressure distribution system is one in which no elevated
storage is provided, and the required distribution pressures aremaintained only by pumping facilities.
Obtains its supply of water through a large intake pipe installed inthe lake basin extended down the water
Water is drawn from the lake to a receiving well by force of gravity,passing through the filtration plant
The water inside the reservoir is pumped by a centrifugal, or pistonpump into the water main with sufficient pressure to serve thespecific needs
Indirect Pressure Distribution It is when the water is drawn from a drilled distribution by indirect
pressure
A turbine pump is mounted on top of the standpipe down the wellbelow the water table
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WATER STORAGEAn extremely important element in a water
distribution system is water storage.
System storage facilities have a far-reaching effect on
a systems ability to provide adequate consumer
consumption during periods of high demand. Required water storage capacity in a distribution
system is met by use of elevated or ground level
storage.
Elevated storage, feeds the water distribution system by
gravity flow. Storage which must be pumped into the
system is generally in ground level storage tanks.
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TYPES OF WATER STORAGE
Ground storage
is usually located remote from the treatment plant
but within the distribution system.
is used to reduce treatment plant peak production
rates and also as a source of supply for pumpingto a higher pressure level.
such storage for pumping is common in
distribution systems covering a large area,
because the outlying service areas are beyond the
range of the primary pumping facilities.
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TYPES OF WATER STORAGEGround storage
Types of ground storage tanks or reservoirs are: belowground, partially below ground, or constructed aboveground level in the distribution system,
may be accompanied by pump stations if not built at
elevations providing the required system pressure bygravity. However, if the terrain permits, this designlocation of ground tanks at elevation sufficient forgravity flow is preferred.
Reservoirs are the most common type of waterstorage structure and are categorized as being groundsupported with a flat bottom and a height no greaterthan its diameter.
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TYPES OF WATER STORAGEGround storage
Concrete reservoirs are generally built no deeper than6-7.5 meters (20-25 feet) below ground surface. Ifrock is present, it is usually economical to constructthe storage facility above the rock level.
In a single pressure level systems, ground storagetanks should be located in the areas having the lowestsystem pressures during periods of high water use.
In multiple pressure level systems, ground storage
tanks are usually located at the interface betweenpressure zones with water from the lower pressurezones filling the tanks and being passed to higherpressure zones through adjacent pump stations.
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TYPES OF WATER STORAGE
Elevated Storage
is provided within distribution system to supply
peak demand rates and equalize system pressures.
In general, elevated storage is more effective and
economical than ground storage because of thereduced pumping requirements, and the storage
can also serve as a source of emergency supply
since system pressure requirements can still be
met temporarily when pumps are out of service.
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TYPES OF WATER STORAGE
Elevated Storage The most common types of elevated storage
are elevated steel tanksand standpipes. Inrecent years, elevated tanks supported by
single pedestals have been constructed whereaesthetic considerations are an important partof the design process.
A standpipe is a tall cylindrical tank normallyconstructed of steel or reinforced concrete.
They are ground supported, flat bottom,cylindrical tanks with heights greater than theirdiameter.
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TYPES OF WATER STORAGEElevated Storage
Elevated storage tanks should be located in the areashaving the lowest system pressures during intervals of highwater use to be effective in maintaining adequate systempressures and flows during periods of peak water demand. These are those of greatest water demand or those farthest
from pump stations. Elevated tanks are generally located at some distance from
the pump station(s) serving a distribution pressure level,but not outside the boundaries of the service area, unlessthe facility can be placed on a nearby hill.
Elevated tanks are built on the highest available ground, upto static pressures of 520 kPa (75 psi) in the system, so as tominimize the required construction cost and heights.
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Types of Cold Water Distribution SystemsDirect or Non-storage
All the plumbing fittings are supplied with cold water directfrom the mains.
A cold water cistern is normally used to feed the hot water
supply system though water heaters are available which can be
fitted direct from the mains.
Advantages Less pipe work, smaller or no cistern make it cheaper to install.
Drinking water is available at all draw of points.
Smaller cistern can be sited below the ceiling. In systems without a cistern there is less risk of water
pollution.
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Types of Cold Water Distribution SystemsIndirect or Storage
All plumbing fittings except the kitchen sink is supplied withcold water via a storage cistern, which can also be used to
supply the hot water supply system.
Advantages Cistern provides a reserve of water if supply is interrupted.
Reduced water pressure on taps reduces wear and noise.
Less risk of pollution to drinking water by back siphonage.
Lower demand on the water main.
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COLD WATER DISTRIBUTION IN BUILDINGS
Water is distributed to the household or
buildings by any of the following methods:
Up-feed method
Water is distributed through normal water
pressure from public water main for use in low
rise buildings
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COLD WATER DISTRIBUTION IN BUILDINGS
Pneumatic tank
Water is distributed through air pressure coming
from suction tank for use in all tall buildings that
cannot be reached by normal water pressure
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COLD WATER DISTRIBUTION IN BUILDINGS
Overhead or Down-feed type
Supplies water to the plumbing fixtures by means
of gravity
The water is pumped to a large tank on top of the
building and distributed to the different fixtures Storage tanks are installed when normal supply of
water from public main is unreliable
Also used when normal pressure is not enough toforce the water to the highest fixture
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WATER PIPE SYSTEM
Water is conveyed from the main source to the
household or buildings by series of pipes: Water main
Refers to the public water connection that are laidunderground along the streets where the house service isconnected
House service pipes Refers to the pipe connection from the water main or any
source of water supply to the building served
Riser pipes
Refers to the vertical supply pipe that extends upwardfrom one floor to the next
Branches Horizontal pipes that serve the faucets or fixtures
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PIPING REQUIREMENTS
The amount of water a pipe will deliver at any one
pressure is a direct result of:
the size of the pipe,
the smoothness of the inside surface and
the pipe length.
The procedures used in selecting pipe size are affected by
whether there is only one building or hydrant being
serviced by the line, or two or more buildings.
Even a small increase in the diameter of the pipe cangreatly increase the amount of water that may flow
through it.
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PIPING REQUIREMENTS
Friction between the inside walls of the pipe and the
moving water creates a force that opposes the flow ofwater through the pipe.
The greater the roughness of the inside of the pipe, the
greater the force caused by friction, and the higher the
pressure required to push the same amount of waterthrough the pipe.
Consequently, pipes with smooth inside surfaces can
deliver more water than pipe walls with rough surfaces
using the same pressure. Pipe connections such as elbows, reducers, tees, unions,
etc., as well as valves, can add greatly to the friction
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TYPES OF PIPES
Galvanized Steel Pipe
Galvanized steel pipe is covered with protectivecoating of zinc that greatly increases its life comparedto black pipe.
It is made in standard 6m lengths with each endthreaded. The pipe is cut and threaded to fit the job.Joints are made by placing a small amount of pipe
joint compound on the pipe threads and screwing onthe fitting.
Galvanized steel pipe is suitable for all piping inside abuilding, but plastic and copper pipe are preferred forunderground installation.
Highly mineralized water greatly reduces the life ofsteel pipe.
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TYPES OF PIPES
Copper Pipe
Copper pipe is available in types "K", "L", and "M". Type "K" is heavy duty - pump suction lines and underground
piping.
Type "L" is standard weight - inside buildings, and
type "M" is light-weight for use only behind walls insidebuildings.
Both types "K" and "L" are available in hard- or soft-tempered form.
Hard-tempered pipe is rigid and comes in 3m to 6m lengths.It is used for exposed piping inside buildings, where it can befit closely to walls or ceilings. It needs very little mechanicalsupport to keep it in position, compared to flexible tubing.
Soft-tempered tubing is excellent for underground use andfor inside existing walls in old buildings.
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TYPES OF PIPES
Plastic Piping
Plastic pipe is available in flexible, semi-rigid, and rigidforms. Flexible pipe is common for undergroundwater piping because of installation ease andeconomy. It is or more in diameter and in coils of100 feet or more.
Solvent welded, or glued, PVC semi-rigid pipe is nowcommon as a result of better and more readilyavailable quality, ditching equipment, and ease of
joining. The joints of polyethylene pipe use nylon orbrass fittings and stainless steel clamps and clamp
screws. Use only pipe fittings that have the National
Sanitation Foundation seal, NSF. It assures that thepipe is safe for use with drinking water.
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PLASTIC PIPES
There are five classes of plastic pipe and fittings
that meet commercial standards established by theASTM for potable household water. Polyethylene (PE)
This flexible or semi-rigid pipe's strength decreases asthe temperature rises, therefore it is for cold-water
lines only. It has pressure ratings between 80 and 160psi. PE pipe is used for hot water heating in concretefloors; temperatures of up to 100F are common forfoot comfort. For this use, however, the best brand ofvirgin plastic rated at 115F should be used. Also,
mixing valves for water temperature control should beinstalled. Lines should also be laid in straight lines toavoid undue stress. PE pipe is available in diameters ofup to 6 inches or larger; and it is joined by threads andclamps.
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PLASTIC PIPES
Polyvinyl Chloride (PVC)
This rigid pipe is available with pressure ratings of 50to 315 psi.
PVC should be used for cold-water only. It is used for some household cold water pipes and
drains and in some permanent irrigation installations. Pipe for pressure water systems should be rated at
least 80 psi. PVC comes in 3m to 6m lengths and common
diameters; and it is joined with a coupling solvent.
It is generally more resistant to crushing or puncturingthan PE pipe, and it will stand slightly highertemperatures.
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PLASTIC PIPES
Chlorinated Polyvinyl Chloride (CPVC)This material is similar to PVC, but it is better for
handling corrosive water at temperatures 40 to
60F above the limits for other vinyl plastics.
It is suitable for hot or cold water lines. Althoughthis type of pipe was developed to handle hot
water, the manufacturer's stress and temperature
limitations should be checked before installing.
Local plumbing codes should be consulted also.
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PLASTIC PIPES
Polybutylene (PB)
This pipe is suitable for both hot or cold waterlines.
Although this type of pipe was developed tohandle hot water, the manufacturer's stress and
temperature limitations should be checked beforeinstalling. Local plumbing codes should beconsulted also.
In both of the classes - PB and CPVC-
manufacturers sometimes make a number ofpipes with different physical characteristics. Careshould be taken in insuring the water systemneeds are met by the pipe selected.
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PLASTIC PIPES
Acrylonitrile Butadene Styrene (ABS)This semi-rigid pipe has pressure ratings between
80 and 160 psi, and is suitable for sewer pipe.
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SIZING OF COLD WATER PIPES
Pipe is categorized based on the wall thickness
(difference between the outside diameter andthe inside diameter), which is termed asschedule, but most pipes are ordered based onthe nominal pipe size, or NPS.
The size of water service pipes is based on themaximum and minimum probable water demand,but in no case shall it be less than 20mmdiameter.
A 20mm service pipe can supply two (2) branches of 12mm diameter pipes deliver water to the house up to 38 l/m sufficient to
serve up to ten (10) fixtures
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PIPE FITTINGS APPLICATIONS Pipe and pipe fittings go hand-in hand.
Just as pipes are used for a variety of residential, public and industrial
applications, so also the pipe fittings. No pipes can be connected without the use of proper fittings and
flanges.
Pipe fittings allow pipes to be installed and connected or joined where
necessary and terminated in the right place.
Pipe fittings include a wide range of products in variousshapes, sizes and materials. With rapid developments in the field of industrial fittings and
continuous research work in this industry, various new products are
manufactured.
Some fittings have certain special features so that they can befabricated on different principles like hydraulics, pneumatic depending
on the end usage.
Fittings include a comprehensive range of products depending on
various applications in which they are applied.
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PIPE FITTINGS BY MATERIALS
Aluminum
Brass
Cast iron
Copper
Malleable
Plastic
Steel
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CATEGORIES OF FITTINGSFittings can be grouped in one of the following
categories:Fittings that extend or terminate pipe runs
Couplings
Adapters
Caps and PlugsFittings that change a pipe's direction
Elbows (ells)
Fittings that Connect two or more pipes
Reducers
Bushings
Flex couplings
Fitting reducers
Adapters
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PIPE FITTINGS BY TYPES
Pi Ad t
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Pipe Adapters Are an extremely important pipe
fitting that extend or terminate pipe
runs. They are used to connect
dissimilar pipes.
Adapters are somewhat similar to
pipe couplings, with the difference
that they connect pipe of different
types, one of which is an IPS (Iron
Pipe Size).
Adapters may have either male or
female IPS threads on one end and
the opposite gender on the other
end, which needs to be welded orsoldered onto a smaller pipe.
Adapters are used in a myriad of
applications but they are typically
used to connect different pipes to
fixtures.
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Bulkhead Fittings Specially designed fittings meant to
allow free flow of liquids in tank, drum
drainage and other plumbingconnections; also used as distribution
outlets in a piping system.
Bulkhead fittings provide full flow of
water and they are also used to attach
flexible pipes with the help of male
adapters. These fittings usually have
left handed threads, which help to keep
the fitting intact and tight while
installing the male adapter.
When used with unions, bulkhead
fittings facilitate the removal of pumpsand accessories.
Bulkhead fittings also come with nuts
and gaskets as accessories. The gaskets
are usually purchased separately.
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Compression fittings are special type of coupling, usually
used to connect two pipes or a pipe to
a fixture or valve.
A compression fitting tightens down a
sleeve or ferrule over a joint to prevent
leakage.
These pipe fittings are very strong and
reliable and can be put on using just a
pair of wrenches; do not require anyheating and go well even with wet
pipes.
Compression fittings are ideal for
household plumbing applications.
Compression fittings are usually madeof materials like:
Brass
Plastic
Copper
Cast Iron
In cases, when compression fittings are
used for joining pipes of two dissimilar
materials, for example PVC and copper, they
should be made of such appropriate
materials that are perfect for the
connection.
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Parts of a Compression Fitting:
The pipe compression fittings consistof three parts:
Compression nut
Compression ring or inner ring or
olive, and Compression seat
A l i f i l d
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Pipe caps act as protective device and are designed
to protect pipe ends of various shapes.
The main purpose of using pipe caps is
to waterproof the connections. They are
also used to close the ends of hydraulic
or pneumatic pipes and tubes.
They are used in the plumbing apparatusof domestic, commercial and industrial
water supply lines, machinery and
processing equipment etc.
They are also fitted on water pump lines
with the sole purpose of removing airblocks.
Pipe caps are highly demanded as an
important category of pipe fittings.
As a large variety of materials are used
for making pipe caps, the buyer should
always take care of the material of the
fitting before going for pipe caps. Some
of the common materials used include:Aluminum
Nylon or polyamide
Polyethylene
Polypropylene
Stainless steel
VinylSilicone rubber etc.
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Common Shapes of pipe caps:Pipe caps are available in variousshapes.
Round
Square
RectangularU Shape Cap
I Shape Cap
Hex Cap etc.
Pipe couplings
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Pipe couplings are fittings that help to extend or
terminate pipe runs. Couplings
extend a run by joining two
lengths of pipe.
They are also used to change pipe
size. They are known as reduced
coupling if they are used to
connect pipes of different sizes. Couplings are also known as repair
couplings. These couplings are
without stops or ridges and they
can be fixed anywhere along the
pipe length for preventing leak of
any kind.
Couplings are of 2 types
Flexible
Rigid
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Pipe elbow fittings are fitting accessories which are used
widely in various industrial sectors in
pipe fitting.
frequently used in pressurized
applications and are available in various
shapes and sizes for use in different
applications.
installed between two lengths of pipeor tube allowing a change of direction,
usually in the 90or 45direction.
Types of pipe elbows are: 90elbow
45elbow
Reducing
Side outlet
Male & female elbow
Street elbow
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Pipe ferrule fittings made of various materials used
especially for joining or binding
one part to another (as pipe
sections).
consist of a circular clamp which
is used to hold together and
attach fibers, wires or posts. It isa type of a ring or cap attached
to an object to protect against
damage, splitting or wear.
A pipe ferrule is also known as a
circular fitting device that is used
to hold the pipes together. Pipe
ferrules are available in various
sizes.
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Pipe Nipple Fittings
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Pipe Nipple Fittings a length of straight pipe with
male threads on both ends.
a connector or a coupling
threaded on both ends.
Pipe nipples are used to allow
plumbing to be connected to a
water heater or other
plumbing. are used to fit straight end hose
or pipe. A combination of pipe
nipples are recommended for
low-pressure discharge andsuction service for various
compatible liquids and not for
compressible products like air,
nitrogen or steam.
Pipe plug Fittings
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p p g g are defined as cap end of fractional
tubes used in a large number of
industries.
These pipe plugs are designed toinsert into the end of tubing to dead-
end the flow.
These pipe plugs come in one piece
body design; easy to replace plugassembly; very easy to maintain and
clean.
The pipe plugs are often plated with
chrome or nickel for a superior finish
and better resistance to corrosion.
Types of pipe plugs are:
Hex
Hollow
square
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Pipe Plug Drive Styles:
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Pipe Union Fittings a type of fitting equipment designed
in such a way to unite two pipes which
can be detached without causing any
deformation to the pipes.
Any kind of small diameter piping
connections requiring a positive seal
and easy assembly as well asdisassembly are made with the help of
pipe union. In other words, the pipe
unions can disjoint two pipes very
easily. They are widely demanded inthe pipe fitting market.
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Pipe Tee Fittings
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Pipe Tee Fittings a type of pipe fitting which is T-shaped having
two outlets, at 90to the connection to the
main line; a short piece of pipe with a lateral
outlet.
Pipe Tee is used to connect pipelines with a
pipe at a right angle with the line. Pipe Tees
are widely used as pipe fittings. They are
made of various materials and available invarious sizes and finishes.
Pipe tees are extensively used in pipeline
networks to transport two-phase fluid
mixtures.
Types of pipe tees are: Bullhead
Female branch
Male & female run
Male
Reducing tee
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Pipe wye Fittings are used to allow one pipe to join
another pipe at some degree or
angle.
As the name suggests, the pipe wyes
are Y-shaped pipe fitting devices.
Pipe wyes are similar to pipe tees.
The only difference is in that thebranch line is angled to reduce
friction which could hamper the
flow. The pipe connection is typically
at a 45-degree angle rather than a
usual 90-degree angle.
Types of pipe wyes: Standard
Reducing
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PIPE JOINT TYPES
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Pipe Joint
Required to connect pipe to itself, a fitting or topiece of equipment
The joint type selected for a particular application
depends on: Pipe material and wall thickness
Pipe contents
System pressure
System temperature Disassembly requirements
Applicable plumbing codes
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CAULKED JOINT A type of joint used for cast-iron pipe
having hub-and-spigot ends. After the spigot-end of one pipe is
placed inside the hub-end of the other,
a rope of oakum or hemp is packed into
the annular space around the spigot
end until the packing is about 1 inch
(2.5 cm) below the top.
Then molten lead is poured into the
annular space on top of the rope.
Finally, the lead is pounded farther into
the joint with a caulking iron.
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COMPRESSION GASKET JOINT A type of joint used only for pipe having
hub-and-plain ends.
Are flexible pressure joints suitable for
gravity drainage and pressurized liquid
systems compatible with the pipe and
gasket.
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COMPRESSION COUPLING
JOINT Rigid non-pressure joints used to join
plain end drainage pipes
Suitable for gravity drainage systems
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THREADED JOINT Can be used for any pipe with walls thick
enough to have threads cut
This rigid pressure joint is generally limited
to 100mm pipe as it is difficult to turn
large pipe Threaded ends come tapered (for
plumbing and utility pipes per ANSI B-2.1)
and standard (for process pipe systems).
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SOLVENT CEMENT JOINT This rigid pressure joint can be used only
with plastic pipe
Each plastic requires a specific
solvent/cement ratio combination
recommended by the manufacturer.
A joint created with solvent cement looks
like a soldered joint, but the cement is
used to soften and dissolve the plasticafter which it hardens into a
homogeneous joint.
SOLDERED AND BRAZED JOINT
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SOLDERED AND BRAZED JOINT Is a rigid pressure-type joint used to join
copper and copper alloy pipes and fittings
The distinction between soldering and
brazing is the temperature required to melt
the filler metal that enters the joint by
capillary action.
In case of brazing, the filler metal (brazing
metal) should have the melting point more
than 450oC, while soldering requires less thanthat. Brazing produces joints stronger than
the pipe itself.
Flux is required for solder and some types of
brazing filler metal but is prohibited for use
with gases installed in health care facilities Filler metal for soldering consists of 50% tin
and 50% lead. No lead is permitted for
potable water systems.
Soldered joints are used for relatively low-
pressure applications
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FLARED JOINT This rigid pressure joint is used for
relatively low-pressure applications onsmall diameter pipes made of soft copper
or other metals.
They are commonly used with capillary
piping in laboratories and small diameter
underground water piping. Proprietary types of flared fittings are
available for high-pressure applications.
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WELDED JOINT Rigid pressure joint formed as butt-fused
joint or socket weld.
Butt-fused joints are created by meltingprepared end metal pipes or square end
plastic pipes, then butting them together
and fusing them, which forms a
homogeneous joint upon hardening.
Metal pipe ends are externally heated
and melted with an electric arc or flame
and filler metal added to form the joint.
For plastic pipe, the ends are melted
separately and brought together to form
the joint with the use of a special
machine. For a socket weld, a plain pipe end Is
placed inside a socket and the end of the
socket fitting is welded to the exterior of
the pipe to form a rigid joint.
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FLANGED JOINT A rigid pressure joint consisting of two
companion flanges, bolted together
and made leak-proof by means of agasket.
Flanges can be installed on the pipe
end by welding, threading or brazing.
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HEAT-FUSED JOINT A rigid pressure joint used only for
thermoplastic pipes
A special socket fitting has resistanceheating wire embedded near the
outer edge facing the pipe to be
joined, complete with pigtails
extended outside the fitting.
An external electrical power source is
connected to the wire pigtails to
generate the heat to melt both the
inside of the socket and the outside of
the pipe in the area where the wire isembedded.
When the material is cool, a rigid joint
has been formed and the pigtails are
cut off.
SPLIT COUPLING JOINT
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SPLIT-COUPLING JOINT This joint requires two types of pipe
end preparation, roll grooving and cut
grooving. The latter method is stronger, but the
roll grooves must be used when the
pipe is too thin for a groove.
These rigid pressure type joints are
well-suited for both pressure andnon-pressure lines.
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WATER SERVICE FITTINGS andDEVICES
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Valves Valve is an equipment designed to stop or regulate
flow of any fluid (liquid, gas, condensate, stem, slurryetc.) in its path.
Valves are categorized depending on their
applications like isolation, throttling and non-return.
It is installed in the piping system based on itsrequirement.
Various type of valves are available depending upon
the type of construction.
The two principal types of valves used to stop the
flow of water in water supply systems are gate valves
and globe valves.
Gate Valves
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Gate Valves
It is operated by raising and lowering a double-faced wedge-
shaped gate.
When the valve is closed, the two faces of the gate are
tightly pressed against the seats, thus effecting a double
seal.
The chief advantages of a gate valve are:
its tight seal
full size straightway opening, which offers no greater resistance
to the flow of water than would an ordinary pipe coupling or
other fitting of equal length.
Either end of this make of gate valve may be used as the
inlet, although there are some makes of gate valves that are
single seated or have only one gate face.
Such valves should be screwed on a pipe with the valve face
to the pressure.
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Globe Valves
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Globe Valves One of the types of valve most commonly used for water
supply systems.
This type of valve has an inlet and outlet end, and a valve
disk, a, that closes against the pressure.
The valve is operated by lowering the disk, a, until it
presses firmly and evenly on the valve seat and thus cuts
off the flow of water. By turning the valve stem to the left,thus raising the valve disk from its seat, the water is
turned on.
Instead of an interchangeable soft disk, some globe valves
have a brass disk that closes on a brass seat. Such valves seldom remain water tight more than a few
months and cannot be repaired as easily and inexpensively as
can soft disk valves; therefore, it is a matter of economy to use
soft seat valves.
Globe Valves
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Globe Valves The principal objections to the use of globe valves are:
the opening through the seat of the valve is not the full area of
the corresponding size of pipe, and therefore not only restricts
the flow but offers considerable frictional resistance
the opening is not straightway, consequently it offers
additional frictional resistance to the flow of water.
they also, when placed on horizontal pipes, form traps thatkeep the pipes half full of water when the pipes are
drained. This latter objection, however, can be overcome by turning the
valve on its side, so the stem will be nearly horizontal. In this
position the opening in the valve seat is as low as the bottomof the pipe and permits all water to drain out.
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Lift Check Valves
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A check valve is an automatic valve that opens to the pressure of
water on one side but closes tightly when pressure is applied to
the opposite end of the valve. A check valve should be used where water should always flow in
one direction and there is a possibility of a reverse flow.
There are two common types of check valves; lift check valves,
and swing check valves.
In a lift valve, the check seats by gravity when pressure in the system
on both sides of the valve is equal.
When pressure on the inlet end of the valve exceeds that in the outlet,
the pressure unseats the check from the seat and permits water to
flow through the valve.
If there is an excess of pressure on the outlet end of the valve, the
pressure will the more tightly seat the check and prevent any water
from passing back through it.
Check valves are made both for vertical and for horizontal pipes.
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LIFT CHECK VALVE
Swing Check Valve
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Swing Check Valve It derives its name from the fact that the metal flap, a,
yielding to the pressure of water, swings on the pivot
and thus presents a straightway opening for the flow
of water.
This type of check valve compares with the lift check
valve about as a gate valve compares with a globevalve.
The swing check valve offers less resistance to the
flow of water through it and has a straightway
opening of almost the full size of the valve. In the lift check valve, on the contrary, the water must pass
through a reduced opening in the valve seat and must
make two right angle turns while doing so.
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Pressure Regulators
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Pressure Regulators Apparatus for controlling or decreasing the pressure of
water within a building and thus relieving the system of
excessive strain. By their use, the static pressure within a building can be
maintained at a pressure of 15, 25 or more pounds, while the
static pressure in the street might exceed 100 pounds; at the
same time, the volume of water or the pressure of the waterwhile running will not be affected by the pressure
reducing valve
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RELIEF VALVES
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RELIEF VALVES Relief valves are automatic valves used on system lines and
equipment to prevent over pressurization.
Most relief valves simply lift (open) at a preset pressure and reset
(shut) when the pressure drops only slightly below the lifting
pressure.
System pressure simply acts under the valve disk at the inlet
of the valve. When system pressure exceeds the force exerted by the valve
spring, the valve disk lifts off its seat, allowing some of the system
fluid to escape through the valve outlet until system pressure is
reduced to just below the relief set point of the valve.
The spring then reseats the valve.
RELIEF VALVES
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RELIEF VALVES An operating lever is provided to allow manual cycling of the
relief valve or to gag it open for certain tests.
Virtually all relief valves are provided with some type of device to
allow manual cycling.
Other types of relief valves are the high-pressure air safety
relief valve and the bleed air surge relief valve.
Both of these types of valves are designed to open completely at aspecified lift pressure and to remain open until a specific reset
pressure is reachedat which time they shut.
Many different designs of these valves are used, but the same
result is achieved.
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F ll P F
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Fuller Pattern Faucets A type of faucet for low
pressure work. This type of cock is quick closing
and closes with the pressure, a
rubber packing, a, effecting the
seal. On account of the quickness
with which this kind of cock can
be closed, each supply pipe to
which they are connected
should be provided with an air
chamber and they should not
be used on high pressure work.
Ground Key Cocks
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May be either stop cocks for controlling water in a pipe,
or faucets for drawing water at a fixture.
The only difference is in their exterior appearance, the principlesof construction and operation being the same for both patterns.
The plug, a, is ground to a watertight fit in the cock, b, and
water is turned on and off by giving a one-quarter turn to
the lever, c.
The principal objection to this kind of a cock is that the constant
wearing of the plug and cock every time the water is turned on
or off, soon causes the cock to leak, and the leak can only be
repaired by re-grinding the plug, which is a tedious and rather
expensive undertaking. Another objection is the quickness with which this type of cock
shuts off the water. Where the water pressure is high, this might
cause serious damage to pipes and fixtures.
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GROUND KEY COCK
Compression Cocks
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A compression cock is used at kitchen
sinks. In construction it is quite similar to
a globe valve and, like one, it closesagainst the pressure.
The core, a, of a compression cock is
fitted with a soft disk packing, b, which
can be easily renewed when the cock
leaks. They are also fitted with a rubber
packing, c, or in some cases with a
ground joint to prevent water spouting
out around the compression stem. Compression stop cocks should be fitted
with an auxiliary stuffing box around the
stem to withstand the back pressure they
are subjected to.
Self Closing Faucets
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Self-Closing Faucets Water can be drawn from a self-
closing bibb only while it is heldopen; the moment the hand is
removed, the faucet is
immediately closed by a spring
provided for that purpose.
When the stem, a, is turned to
the left it raises the block, b,
thus compressing the spring, c,
which, as soon as the pressure
is removed, returns to its
original shape, thus closing the
faucet.
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Water hammer (or hydrostatic shock) is a noisy pipe problem that occurs when valves are
shut off quickly. You may hear banging water pipes, or clanging, rattling, or rumbling
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q y y g g p p , g g, g, g
noises in the water piping when a plumbing fixture, sink, or clothes washer turns off.
Water hammer can damage pipe connections and result in leakage.
Water hammer works like this: water passing through a pipe has momentum or velocity.
When the valve is shut quickly, the momentum of the water carries it into the valve withconsiderable force.
Since water is essentially incompressible, a large pressure is built up against the valve, and
there is low pressure upstream in the pipe. The high-pressure water wants to flow to the
low-pressure area.
This happens so quickly that a small vacuum is created against the valve as the water
moves away from it. This can result in cavitation as the water is pulled back against the
valve a second time.
This continues back and forth in slowly diminishing shock waves. Pressures up to 600 psi
(some sources say 1000 psi) can result from water traveling up to 3,000 miles per hour, for
very short periods.
Water hammer can result in loud noises in supply plumbing pipes. Water hammer only
occurs as valves are closed. If a valve is closed slowly, and the noise does not occur, one
can be sure that water hammer is the problem.
Water hammer is common with quick-closing electrically operated valves on appliances
such as washing machines and dishwashers Air chambers can be installed to control water