COLDWATERDISTRIBUTIONINBUILDING

Prepared By: Heina Van Quimintan

By normal water pressure By overhead feed system By air pressure system

The normal water pressure from the public water main is normally inadequate to serve buildings. The alternative solution is either by the Overhead Feed System or by the Air

Pressured Distribution System.

Water is pumped into a large tank on top of the building and is distributed to the fixtures by means of gravity.

water is not affected by peak load hour not affected by power interruptions time needed to replace parts will not affect the regular supply of water

Advantages:

OVERHEAD FEED

SYSTEM

X water is subject to contamination

X high maintenance costX occupies valuable

spacesX requires stronger foundation and other

structure to carry additional load of tank and

water

Disadvantages:

OVERHEAD FEED

SYSTEM

When pressure supplied by city water supply is

not strong enough Compressed air is

used to raise and push water into the system

AIR PRESSURE

SYSTEM

with compact pumping unit sanitary due to air tight water chamber oxygen in the compressed air serves as purifying agent economical (smaller pipe diameter) less initial construction and maintenance cost adaptable air pressure air pressure serves zones of about 10 floor intervals

X water supply is affected by loss of pressure inside the tank in case of power interruption

Advantages:

Disadvantages:

AIR PRESSURE

SYSTEM

AIR PRESSURED WATER DISTRIBUTION SYSTEM

Four mechanical devices used in air pressurized water supply system

large tank An Air Compressor

An automatic pressure control

switch

A single or

duplex

centrifugal

pump

Operating Principle of an Air Pressure Water Distribution

System“ Air is elastic or compressible

and water is inelastic or noncompressible ”

Thus, when air compressed into a closed compartment under atmospheric pressure to the extent of one half its volume content, the pressure will increase up to 15 pounds per square inch (psi). This pressure inside the tank is capable of elevating water up to 10.50 meters high.

By compressing the original pressure inside the tank is not enough. The slightest draw of water from the faucet substantially decrease the pressure and there is a possibility of water clogging inside the tank.To overcome this deficiency, an air compressor unit is installed so that the volume of air inside the tank will be increased to a pressure of one half the minimum required.An automatic pressure switch control that regulate the starting and the stopping of motor pump.

The ideal air pressure range from 20 to 40 psi.

is an innovation of the air pressurized water distribution used on tall buildings that could not served adequately by street main It is a Triplex Pump installed to operate in sequence according to the volume of demand.

DIRECT UP FEED PUMPING SYSTEM

Advantages:

Disadvantage:

Eliminate the construction of a large house water tank. low construction cost Eliminate periodic cleaning of the tank

x dependent on electricity

P U M P SP U M P S P U M P S

Upfeed

Upfeed

Supply

1

2

3

4

5

6

7

8

9

10 Floor

Control Panel Control Panel

Pressure Sensor

Down

House tankFloat switch

B. Same as A with Surge TankA. Constant Pressure C. Conventional Roof Tank

Roof

Basement Surge Tank

Stree

tMain

DIRECT UPFEED SYSTEM- TRIPLEX PUMP

s

The principle of operation is simple

When the water demand is small, the small pump (jockey) will operate. As the water consumption increases to the point that the jockey pump could no longer cope with, the second larger pump starts automatically to replace the operation of the jockey. As demand increases further to reach its peak, the third largest pump with full capacity to supply the entire building, will automatically operate to replace the second pump. Under this principle, only one pump operates at a time, depending upon the volume of water demand.

Friction – when alluded to in the plumbing system, refers to the resistance produced by the flowing water with the fittings and interior surface of the pipe.

In water supply distribution, Friction is also defined as the resistance between the molecules of water.

FRICTION

INWATER

SUPPLY

1. All water pipes should be installed straight and direct as possible.

2. The use of turns, offsets and traps should be minimized if cannot be avoided.

3. A pipe with plain and smooth surface should be preferred.

4. The use of fittings, stops and other devices connected to the distribution lines should be minimized.

5. All fittings and joints must be properly connected.

Friction Minimized:

is the force required to move the water inside the pipe.

Pressure

the pressure exerted by the water at rest Static Pressure

refers to the pressure range measured

over a period of 24 hours.Normal pressure for a residential

house ranges from 30 to 40 psi. Lower

than this value may result toinsufficient flow of water. On

theother hand, greater than 50 psi

maycause pipe hammering or evenbursting of pipe joints.

Normal Pressure

by installing this valve, an excessive pressure can be minimized

Pressure Reducing Valve

Water vibration andhammering, can be

checkedby installing anpipe at the back of the

faucet

Air Chamber

The maximum and minimum pressure at which

proper function of the water supply system can be maintained

Critical Pressure

The loss in rate of flow, due to friction between water

and the walls of the pipe.

Friction Head

Loss

The variations in pressure between the water main and

the outlet end of the water service.

Pressure

Loss

Other Causes of Pressure Loss

Simultaneous draw or use of water

Height or distance to which the water must flow

Fluctuation of water pressure in the water main

Mineral elements in water that adhere to the interior of the pipe reducing the diameter

Inadequate size of the pipe

MAXIMUM AND PROBABLE DEMAND

Maximum Demand

refers to the maximum water discharge of fixtures in terms of fixture units.

The maximum demand of water is equal to the Total Fixture Units in plumbing system, where one unit is valued at 8 gallons of water discharge per minute interval

Fixture Group Fixture Units

Water Closet 10

Pedestal Urinal

10

Stall/ Wall Urinal

5

Lavatory 2

Bathtub 4

Shower head 4

Service sink (Office, etc.)

3

Kitchen sink (Hotel /

Restaurant)

4

Fixture Group

Fixture Units

Water Closet 6

Lavatory 1

Bathtub 2

Shower head 2

Bathroom group

8

Separate shower

2

Kitchen sink 2

Laundry Tray 1-3

3

Combination Fixture

3

PrivatePublic

Demand Weight of Fixtures in Fixture Units

A residential house has 3 water closets, 3 lavatories , one kitchen sink and 3 shower baths. Determine the maximum demand of water.

6 x 3 = 18 units1 x 3 = 3 units2 x 1 = 2 units2 x 3 = 6 unitsTotal 29 units

Maximum Water Demand:29 units x 8 = 232

gallons

Example :

Fixture Group

Fixture Units

Water Closet 6

Lavatory 1

Bathtub 2

Shower head 2

Bathroom group

8

Separate shower

2

Kitchen sink 2

Laundry Tray 1-3

3

Combination Fixture

3

Private

MAXIMUM AND PROBABLE DEMAND

Probable Demand

One factor to be considered in determining the size of the water service pipe.

The fewer the number of fixtures installed, the higher the percentage of probability of their simultaneous use, and the greater the number of fixtures installed, the lower the percentage of probable simultaneous use.

The Probable Demand is not likely to exceed 25% of the Maximum Demand, especially for average sized buildings.

Determine the probable demand of the following fixtures installed : 2 water closets, 1 lavatory, 1 bathtub, 1 shower bath and 1 kitchen sink.

Number of Fixture Units Percentage of Simultaneous Use

1 to 56 to 50

51 or more

50 to 100 %25 to 50 %10 to 25 %

Example

2 water closets 2 x 6 = 12 units1 lavatory 1 x 1 = 1 unit

1 bathtub 1 x 2 = 2 units1 shower bath 1 x 2 = 2 units1 kitchen sink 1 x 2 = 2 units

Find the number of fixture units then multiply by 8

Multiply19 units

19 units x 8 = Maximum demand

Assume 30% reduction of 152 gallons.

152 x .30 = 45 gal.

152 gallons

152 – 45 =

Subtract from maximum demand of 152 gallons

107 gallons Probable demand

Public water distribution system usually has an average water pressure of 50 psi. that is only adequate to serve building less than 5 storey high.

Types of Pump

Centrifugal Pump

Piston Pump

WATER PUMPS AND

LIFTS used on small water distribution system for elevating water in wall or other sources

Tall building water distribution system

Piston Pump (Double Acting)

Centrifugal Pump

WATER SERVICE FITTINGS AND

DEVICES

Valve is necessary to avert serious

damages of the installations in case of service

breakdown.

Types Of Valve Gate Valve

Globe Valve Angle Valve Check

Valve Foot Valve Safety

Valve

Gate Valve

The gate valve is used mainly to completely close or completely open the line but not necessarily to control the flow of water.

Wedged Shape Double Disc Valve

Two TypesGate Valve

Globe Valve

Plug Type Disc Valve Conventional Disc Valve Composition Disc Valve

It is a type of valve used for regulating flow in a pipeline consisting of a movable disk-type element and a stationary ring seat in a generally spherical body.

Three Types

Plug Type Disc ValveHas a wide bearing surfaces producing a good resistance to the cutting effect of scale, dirt.. etc

Has a pressure tight bearing between the disc and the seat. It isrecommended for cold and any temperature service.

Used for different services such as oil,gasoline, steam, hot or cold water

Globe Valve

Conventional Disc Valve

Composition Disc Valve

Check Valve

The swing check valve

prevent reversal of flow in the line. It is principally used in industrial pipings.It is classified into two types namely:

The lift check valve

Lift Check Valve

Vertical Check Valve

Horizontal Check Valve

Swing Check Valve

Angle Valve

Located at the lower endof the pump and used mainlyto prevent loss of priming ofthe pump

Operates in the same manner as the globe valve available in similar range of disc and seat design. It is used in making 90 degree turn in a line reducing the number of joints

Foot Valve

Safety Valve

The corporation stop Curb stop Curb stop box Meter stop Water meter

is used on water systems, heating systems, compressed air lines and other pipe lines with excessive pressure.Other Water

Service Fittings and Devices

Inserted into the water main. It serves as a control stop for the water service. It also serves as a shut off for disconnection of service

Corporation Stop

Installed on the water service between the curb and the sidewalk line. Services : As a control stop, As a shut off in case the basement becomes flooded and As a control valve in case the building is not used on winter time.

Curb Stop

serves as a controlling stop for the building installation

Meter Stop

Is a device used to measure the amount of water that passes through the water service.

Water Meter

Item Cause Bad Effect Correction

Hardness Calcium and magnesium salts from underground flow

Clogging of pipes by scale, burning out of boilers and affects laundry & food preparation

Ion-exchangerZeolite process

Corrosion Acidity, entrained oxygen & carbon dioxide (low pH)

Closing of iron pipe by rust, destroy brass pipe

Raising the alkaline content

Pollution Contamination by organic matter or sewage

Disease Chlorination by sodium hypochlorite or chlorine gas

Color Iron and manganese Discoloration of fixtures and laundry

Precipitation by filtration through manganese zeolite (oxidizing filter)

Taste and odor

Organic matter Unpleasantness Filtration through activated carbon (purifier filtration)

WATER QUALITY PROBLEMS AND THEIR CORRECTIONSIN PRIVATE WATER SYSTEM