1. Available Water Flow Meter Size Typical flow depending on size
5/8” = 12 GPM
¾” = 15 GPM
1” = 20 GPM

2. Available Water Flow Determine available flow with Bucket Test
Water meter: measure at backflow preventer

3. Available Water Flow
Bucket Test
Pump: measure at pump

4. Bucket Test Gallons per Minute (GPM)
(5 gallons / seconds to fill) X 60 seconds =
Gallons per Minute (GPM)

5. 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

6. Low Pressure…. High Pressure….. Instructor:
The spray head on the left is operating with a high pressure resulting in a fine droplets and mist. The spray head on the right is operating with a low pressure resulting in larger droplets.
High Pressure…..

7. High Pressure Instructor:
This sprinkler system in operation may make a good picture. However, the mist in the air is an indicator that the pressure in the system is higher than recommended. The resulting mist can easily be blown away by wind, and often there is a non uniform distribution of water to the soil.

8. Low Pressure Instructor:
The sprinklers appear to be operating with lower than recommended pressure. The droplets at the end the stream are very large and concentrated.

9. Low Pressure Instructor:
Sports field with poor turf quality. The small green spots in the outfield grass are sprinkler locations. Low pressure may be a problem for those sprinklers.

10. Low Pressure Instructor:
This is what turf may look like when the sprinklers operate at lower than recommended pressure.
Summarize why hydraulics is important. The bottom line is if you designed, or installed, or maintained one of the above systems for a customer, will they be satisfied with your work?

11. Pressure Measurement Pressure gauge Instructor:
One or more pressure gauges in irrigation system help in operation and maintenance of a system. This pressure gauge is stalled adjacent to pressure regulator that can be adjusted to decrease the pressure in this irrigation system.

12. Pressure Gauge (Pitot Tube)
Measure operating pressure
Instructor:
This gauge indicates pressure in “psi” and “bars”. psi is the common unit of measurement. This will be discussed later.

13. Water Pressure
Created by:
Elevation
Weight of water

14. Water Pressure 1’ of elevation (head) = 0.433 psi
In irrigation terms, 1’ of elevation is referred to as 1’ of head
1 in.
12 in.
0.433 psi
Instructor:
Important to point that it’s the height that creates the pressure not the shape or size of the container

15. Water Pressure
2.31’ of elevation = 1 psi
2.31 ft.
1 psi

16. Pressure and Container SizeB C
What (relatively) will be the pressure at the base of various containers?
Same for all (only the height of water column determines the pressure )