2011-03 head losses calculations.pdf
TRANSCRIPT
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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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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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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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