Class 1 and 2

Introduction &Hydraulics in Plumbing

Building Services 1

Reference:

Plumbing Practicesby-Syed Azizul Haq, PEng

Introduction:

Selecting appropriate pipe, equipments, accessories and its installation and maintaining is the science.

The word plumbing derived from Latin word “Plumbum” means lead.

Plumbing is a subject combination of arts and science.

Efficient laying out of pipes and using befitting fittings is the art of plumbing.

Introduction (contd…)Definition:

Basic objectives:

Supplying accepted quality and adequate quantity of waterDisposing of wastes sanitarily and quickly.

Plumbing is the art and science of designing, installing and maintaining pipes, fixtures, equipments and its accessories for controlled flow of fluids (water, gas and water conveying waste) required in a building and its premises.

Achievement of ObjectivesTo meet the objectives, the Planning, design installation and maintenance of plumbing should reflect the following achievements.

1.Safety

2. Sanitation

3. Good environment

4. Convenience

5. Comfort

6. Economy

7. Durability

8. Legality

1.Safetyi. Provide safe drinking water.ii. Safe disposal of wastes. iii. Piping and appliances are safely installed.iv. Equipments are fitted with proper safety devices.v. Structural safety has not been impaired by plumbing installations.

2. Sanitationi. Non-polluting system.ii. Waste disposal in public sewer system or in specified disposal area.

3. Good environment i. Non-hazardous to the environment that may be created by improper waste disposal ii. Surroundings free from bad smell.

4. Convenience i. Providing appropriate type and good quality, proper sized, pipe, fixtures and fittings. ii. Installing optimum number of fixtures and fittings.

Achievement of Objectives (contd.)

5. Comfort i. Installing fixtures at appropriate position and comfortable heights

considering users desire and disability.ii. Minimizing noise sound developed in the plumbing system.

6. Economy i. Providing optimum sized piping, fittings and equipment. ii. Installing fixtures, fittings and appurtenances of economy price.

7. Durability i. Providing long lasting pipes, fitting, fixtures and accessories.ii. Jointing the fixtures and pipe fittings properly.iii. Providing protective measures for all the elements in the plumbing system. iv. Testing the plumbing system to check for leakage and defective workmanship. v. Checking installation of the equipment for proper functioning before the system is put into operation.8. Legality i. Designing the plumbing system in accordance with local code of practice or by laws.

Achievement of Objectives (contd.)

Scope of plumbing works:A. Water supply system for

1. Human consumption like drinking, Culinary purpose, washing and bathing. Three nature of water are supplied in buildings

i. Cold water ii.. Hot water temperature varies from 40 C to 80 C iii. Chilled water.

3. Recreational purpose e.g. for swimming pools, fountains, water falls etc.B. Waste disposal from buildings.

C. Rainwater management

D. Gas supply

2. Fire fighting by water jetting on fire.I. Dry riser systemIi. Wet riser system

Conveying human excreta wastes by flushing water and flowing wastewater sanitarily through pipes to safe disposal point.

Utilizing maximum rainwater for human consumption and other purposes and disposing of the rest

For using as fuel and live saving gas supply in hospitals, clinics etc.

The pressure is a function of water height and density of water i.e.

P = hD. where h = depth of water in ft and D = density of water

For 1 ft of water column, pressure exerted is

P = h D= [(1 ft) x (62.4) 1b /ft 3)] (1ft2 / 144 in2 ) = 0.433 h psi/ ft depth.

So p = 0.4333 h psi

So one psi pressure is developed for 1/0.433 = 2.304 ft of water column.

h = 2.304 p ft of water column.

Static water pressure

Absolute pressure is the gauge pressure plus 14.7 psi because at mean sea level where the absolute atmospheric pressure is 14.7 psi. But the gauge reads zero pressure there.

Water flows in a pipe from a higher position to lower level due to the gravitation force. The velocity of flow is computed by Mannigs formula.

V= 1/n R2/3 S 1/2 where V = Velocity of flow in ft/ see. For circular pipe R = D/4 , S = Slope of pipe ft / ft.

1. Earthen rough channels 0.05

2. (a) Regular-shaped earth channel  

  (b) Tubular steel 0.02

  (c) Fine well-packed stone  

3. (a) R.C.C. pipes 0.015

  (b) Bricks in smooth condition  

  (c) Smooth stone  

4.   Stoneware pipes, Cast-iron pipes and Welded steel pipes

 0.013

5.   Asbestos cement 0.012

6.   Plastic pipes 0.011

Table : Value of n for Flow in Channels

Flow in pipes under gravity:

Flow of water in a pipe under pressure is determined by formula expressed as V = 1.318 CR0.63 S0.54

C=Coefficient that depends on the material and age of pipe. S- Slope of the hydraulic gradient .

Flow in pipe under pressure:

SL. No.

Pipe Material C

1 Asbestos cement 140

2 Cast iron  

  a. Cement lined 130 to 150

  b. New, unlined 130

  c. 5- year-old, unlined 120

  d. 20-year-old, unlined 100

3 Concrete 130

4 Copper 130 to 140

5 Plastic 140 to 150

6 New welded steel 120

7 New riveted steel 110

Table for value of C.

To avoid excessive noise in piping, fittings and valves and occurrence of cavitation it is recommended that maximum velocity in water supply piping shall be limited to no more than 2.4 m/s (8 ft / sec). 

The velocity of flow shall be limited to 1.2 m/s (4 ft /sec) in branch piping from mains, headers and risers to water outlets where supply is controlled by quick-closing devices like flush valve, quick closing faucets or valves, self closing faucets or other similar type.

Limitation of Velocity of flow

In drainage pipe the flow shall be at least 2 ft/sec. This is said to be self cleansing velocity. The maximum velocity is about 8 ft/sec.

Excessive Water Pressure

a)      Bursting of pipe.

b)      Failure of pipe joints and for supports.

c)      Fracture of valve and equipment.

d) Excessive pressure will result in excessive velocity in the flow.

Excessive velocity

Will create nuisance by

a)      Producing noise in pipe.

b) Producing vibration in pipe

c)      Splashing of water from faucet.