Chilled Water Piping Design

Chilled Water Piping Design



Chilled Water Piping Design


Requirements :

  • Water Flow Rate  .  ( GPM  ) 
ECWT Entering Chilled Water Temperature = 54 F' = 12 C' ( in Egypt )

LCWT : Leaving Chilled Water Temperature = 44 F' = 6 C'  ( in Egypt )

ᐃT = ECWT - LCWT =      10 F     

Q = MCPᐃT

M : Water Flow Rate    ( GPM )


GPM = T.R * 24 / ᐃT

  • IN Egypt (  1 T.R = 2.4 GPM  @ ᐃT = 10 F' )
  • IN Arab Gulf States ( 1 T.R = 2.4 GPM  @ ᐃT = 12 F' )

Pipe diameters are determined and there are factors:

  • The velocity of the water inside the pipes ( 2 : 10  feet / s ) and the appropriate value ( 5 fteet )
  • The Pressure drop  should not exceed ( 10 ft / 100 ft) and the appropriate value ( 4 ft / 100 ft )
  • Pipe Material ( Galvanized steel or Seamless black steel schedule 40 )
  • Chilled water cycle is closed


Pipe diameters can be determined by one of the methods :

  • Friction Chart
  • Friction Table
  • Pipe Sizer Program
  • Pipe Flow Wizard Program

Example :

ᐃT = 10 F'    velocity = 5 ft/s       



GPM = T.R * 2.4 
We start with the farthest point
  • @ AHU 1   Flow Rate = 20 * 2.4 = 48 GPM
  • @ AHU 2   Flow Rate = 15 * 2.4 = 36 GPM
  • @ AHU 3   Flow Rate = 20 * 2.4 = 48 GPM
  • @ AHU 4   Flow Rate = 15 * 2.4 =  36 GPM
  • @ AHU 5   Flow Rate = 10 * 2.4 =  24 GPM



We start with the farthest point

  • From ( 3 s.t ) to ( 4 s.t  )  24 GPM 





  • From ( 2 s.t ) TO ( 3 s.t ) = 24 + 36 = 60 GPM




  • From ( 1 s.t ) TO ( 2 s.t ) = 48 + 60 = 108 GPM


  • From ( G.F ) TO ( 1 s.t ) = 108 + 36 = 144 GPM



  • From ( Chiller ) TO ( G.F  ) = 144 + 48 = 192 GPM


Through this table, we get the pipe diameters






You can use the chart if you like


Thank You

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