Factors Affecting Maximum Flow from Dry Hydrants and Dry Hydrant Sizing and Standardization
Maximum Flow Factors
Maximum flow [A] is dependant on Maximum Usable Pressure (MUP)
Where:
- Atmospheric pressure [B]
- Elevation above sea level
- Atmospheric conditions [C]
- Static lift [D]
- Water vapor pressure [E]
- Water temperature
- Losses in Dry Hydrant
- Pipe and fittings [F]
- Diameter
- Length
- Interior Roughness
- Strainer
- Area of openings
- Velocity head [H]
- Diameter of pipe
- Loss in sudden reduction [I]
- Ration of DL and DS
- Pipe and fittings [F]
- Loss in suction hose [J]
- Length
- Diameter
Maximum Usable Pressure (MUP) = AP - SL - VP - MPP
Where:
- AP = atmospheric pressure in psi
- SL = static life in psi
- VP = vapor pressure in psi
- MPP = minimum pump pressure - pressure required at the suction of the pump