Available Water Flow
Meter Size• Typical flow depending on size
– 5/8” = 12 GPM– ¾” = 15 GPM– 1” = 20 GPM
Available Water Flow
Determine available flow with Bucket Test• Water meter: measure at backflow preventer
Available Water Flow
Bucket Test• Pump: measure at pump
Bucket Test
(5 gallons / seconds to fill) X 60 seconds =
Gallons per Minute (GPM)
Available Pressure
Pounds per Square Inch (PSI)• Static PSI
– Pressure when water not moving– Measure with PSI gauge on water spigot (meter)
• Operating PSI– Pressure during operation
High Pressure…..
Low Pressure….
High Pressure
Low Pressure
Low Pressure
Low Pressure
Pressure Measurement
Pressure gaugePressure gauge
Pressure Gauge (Pitot Tube)
• Measure operating pressure
Water Pressure
Created by:Elevation
– Weight of water
Water Pressure
1’ of elevation (head) = 0.433 psiIn irrigation terms, 1’ of elevation
is referred to as 1’ of head
1 in.
1 in.
12 in.
0.433 psi
Water Pressure
2.31’ of elevation = 1 psi
1 psi
2.31 ft.
Pressure and Container Size
What (relatively) will be the pressure at the base of various containers? Same for all (only the height of water column
determines the pressure )
A B C
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