Water Supply Pipe sizing formula
The formula used to calculate the pipe size for water supply systems is based on the flow rate, pressure loss, and the characteristics of the pipe material. There are different formulas available, but one commonly used equation is the Hazen-Williams equation. Here is the formula:
Q = 7.48 * C * D^2 * (H*L)^0.54 / S^0.63
Where:
Q = Flow rate (gallons per minute or liters per second)
C = Hazen-Williams coefficient (a value that represents the roughness of the pipe)
D = Internal diameter of the pipe (inches or millimeters)
H = Head loss (feet or meters)
L = Pipe length (feet or meters)
S = Hydraulic gradient (a value that represents the pressure loss per unit length of the pipe)
The Hazen-Williams coefficient (C) varies depending on the pipe material. Here are some typical values:
Copper: C = 150
Galvanized steel: C = 120
PVC: C = 150
PEX: C = 150
HDPE: C = 150
To determine the pipe size using the Hazen-Williams equation, you would rearrange the formula to solve for the pipe diameter (D):
D = (Q * S^0.63) / (7.48 * C * (H*L)^0.54)
It's important to note that this formula provides an approximation and may not account for all factors. Other equations, such as the Darcy-Weisbach equation, may be used for more accurate calculations. Additionally, local codes and regulations may have specific requirements or recommendations for pipe sizing, so it's always advisable to consult with a professional MEP consultants like Kromatics for precise calculations in your specific situation.
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Water Supply Pipe sizing formula
