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subbby
subbby is offline
#1
Feb19-13, 12:30 PM
P: 18
The following is the advancement of what I discussed in the link http://www.physicsforums.com/showthr...66#post4274966

Problem Statement
To calculate Pump Discharge Pressure, Calculate the wattage for the pump

Data :
  • Water @ 85 Degree C
  • Flow in for 24” pipe : 3010 m^3/hr
  • Flow in 8” pipe : 405 m^3/hr
  • Total length of pipe = 50ft
  • Nozzle Dia : 1"
  • Nozzle pressure : 100 psi
  • Nozzle Gallons per minute = 119
  • Number of Nozzles = 110 (placed equidistant along the length of the pipe)
  • Kinematic & Dynamic Viscosity of water can be found on : http://www.engineeringtoolbox.com/wa...ity-d_596.html


Is my approach (mentioned below) correct ?
Pump Discharge Pressure = Pressure Loss owing to flow thru Horizontal Pipe + Nozzle Pressure* Number of Nozzles
Then,
  • Find Reynolds Number
  • Determine if its turbulent or laminar flow?
  • Find the relative roughness of the pipe
  • Find the friction factor, either from Moody’s chart or Colebrook equation
  • Then calculate pressure loss = (fρLV^2)/(D*2) in Pascal


Now calculating Nozzle Pressure ,
  • Already given that per nozzle 100 psi. So total pressure loss owing to nozzles; is 100*110 and convert to Pascal units.

Then add ;
  • pressure loss (calculated above) with the Pressure loss owing to those 110 Numbers of nozzles...
    and, use the above addition and multiply with the flow rate to attain the wattage ?


Is this approach Correct ? Am I missing something ?
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