2011-03 HEAD LOSSES CALCULATIONS.pdf

7/27/2019 2011-03 HEAD LOSSES CALCULATIONS.pdf

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HEAD LOSSES CALCULATIONS

FERNANDO CHANDUVI

KINGSTON JAMAICA

MARCH 2011

TCP/JAM/3203 PROMOTING RAINWATER HARVESTING

AND SMALL SCALE IRRIGATION IN SOUTH SAINT

ELIZABETH

FAO AND NATIONAL IRRIGATION COMMISSION LIMITED


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HEAD LOSSES CALCULATIONS

ACKNOWKEDGEMENT IS GIVEN TO MR. ASHER AZENKOT (CARDI)

M.Sc. OF THE MINISTRY OF AGRICULTURE, EXTENSION SERVICE,

FIELD SERVICE WHO PREPARE THE BASE MATERIAL IN A PDF FILE.


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WATER FLOW IN PIPES


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WATER FLOW IN PIPES


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WATER FLOW IN PIPES


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SAMPLE CALCULATIONS

ANSWER:

a. Convert m3/h to cm3/sec, 27,780 cm3/sec

b. Cross section of pipe, 314.2 cm2

c. Water flow velocity, 88.8 cm/sec


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S

A

M

P

L

E

C

AL

C

U

L

A

TI

O

N

S


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SAMPLE CALCULATIONS

ANSWER: Q = 67.8 m3/h and V = 9.6 m/sec


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SAMPLE CALCULATIONS


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HYDROSTATIC


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HYDROSTATIC


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HYDROSTATIC


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HYDROSTATIC


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HYDROSTATIC


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HYDROSTATIC

http://udel.edu/~inamdar/EGTE215/Hydrostatics.pdf


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PRESSURE HEAD


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PRESSURE HEAD

WE KNOW THAT 1 ATMOSPHERE = 0.76 m OF MERCURY COLUMN

SPECIFIC WEIGHT OF WATER = 1 kg/dm3

SPECIFIC WEIGHT OF MERCURY= 13.6 kg/dm3

THEREFORE:

1 ATMOSPHERE = 10.33 meters of water column.


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HEAD LOSSES: EMPIRICAL FORMULA


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C COEFFICIENTS FOR PIPES


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S

A

M

P

L

E

C

A

L

C

U

L

A

TI

O

N

S


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HEAD LOSS IN A PIPE


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HEAD LOSSES IN PLASTIC PIPES


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HEAD LOSS IN PIPES

http://www.engineeringtoolbox.com/pump-head-pressure-d_663.html

http://www.engineeringtoolbox.com/hazen-williams-water-d_797.html

http://www.piping-toolbox.com/pvc-pipes-friction-loss-d_802.html

http://www.lmnoeng.com/hazenwilliams.htm


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HEAD LOSSES IN PIPES

TOTAL HEAD LOSS = 22 meters


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HEAD LOSS IN PIPES


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HEAD LOSS IN PIPES

Visit also FLOW CONVERTER in the WEB

Difference in elevation: 125-94 = 31 meters = 89 feet

Head loss= 16.2 feet = 5.62 m (from Engineering Toolbox)

Required pressure at head of field = 4 atm = 41.32 m = 118.7 feet

TOTAL HEAD REQUIRED AT PUMP = 89 ft + 16.2 ft + 118.7 ft

TOTAL HEAD REQUIRED AT PUMP = 223.9 ft = 77.91 m = 7.5 atm

2,155 feet


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LOCAL HEAD LOSS


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MINOR LOSS COEFFICIENTS


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HEAD LOSS IN PIPES AND FITTINGS


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LATERAL LINES


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REDUCTION COEFFICIENTS


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CHARACTERISTICS OF LATERAL PIPE


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PRESSURE AND HEAD LOSS IN LATERAL


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FLOWS IN LATERAL


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HEAD LOSS ALONG A LATERAL PIPE


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EXAMPLE PROBLEM

Example:

A flat field, 360 x 360 m, is irrigated with a hand moved

aluminum lateral pipe (C = 140). The water source to the

lateral pipe is from a sub main, which crosses the center ofthe field. The selected sprinklers are Naan 233/92 with a

nozzle of 4.5 mm, 25 m pressure of (hs) and flow rate (qs ) of

1.44 m3/hr. The space between the sprinklers is 12 meters

apart, and the location of the first sprinkler is 6 meters awayfrom lateral inlet. The riser height is 0.8 meter and the

diameter is 3/4".


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EXAMPLE PROBLEM

360 m

360 m

Lateral line


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EXAMPLE PROBLEM


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EXAMPLE PROBLEM


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EXAMPLE PROBLEM


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EXAMPLE PROBLEM


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EXAMPLE PROBLEM


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THANK YOU VERY MUCH


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Documents

2011-03 HEAD LOSSES CALCULATIONS.pdf