BAE Department - University of Kentucky
Allows calculation of pipe diameter and water pressure on up to four water points fed by city water.
Friction loss calculations are performed using Darcy-Weisbach friction loss.

Basic Input Data
Number of cattle: (head)
Water intake (gal/animal-day): (between 10 and 20 gpd/animal; bigger animals will drink more water)
Drinking time (minutes/day): (See information below for best selection.)
Pipe diameter (in): (pipe diameter can be 3/4-in, 1-in, 2-in, etc.)
Friction factor: ( use a value between 0.020 and 0.025; the smaller the pipe diameter the higher the friction factor )
Pressure at city water line (psi): (usually between 40 and 45 psi)

Drinking Time:  If the water tank or drinking trough will hold at least 75% of the total daily requirement, this time can be as much as 24 hours (1440 minutes).  If a small tank is used, plan for 4 hours (240 minutes).  If the paddocks are small and the cattle will wander back and forth to water a few at a time, you can probably design for up to 12 hours (720 minutes).  If the fields are large and the cattle tend to water as a group, plan for as large a tank as practical and a 4 to 6 hour drinking time.

  L1   L2   L3     L4  
        GL1       GL2       GL3         GL4


  Symbol Description
  CW City water connection
  GL Ground Level of city water connection
  L1 - L4 Length of pipe sections in ft at 4 points
  GL1 - GL4 Ground level at 4 points
(a)If you do not have the exact ground level data you can get a pretty good estimate using a GPS receiver or
from a topographic map of your county.

Darcy-Weisbach Equation

This is the Darcy-Weisbach Friction Loss Equation:
where f is the friction factor, L is the length of the pipe, D is the diameter of the pipe, V is the velocity of water in the pipe, g is the acceleration due to gravity, Q is the flow rate, and A is the cross-section area of the pipe.
Energy losses for flow through ducts and pipes consist of major losses and minor losses. Major losses are due to friction between the moving fluid and the inside walls of the duct. Major losses are computed using the Darcy-Weisbach friction loss equation (which utilizes the Moody friction factor). Minor losses are due to fittings such as valves and elbows. In this case we assumed minor losses to be 0.02-ft.

Original Web Version

Updated 04/12/2013

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