Sprinkler System Design

Calculating the volume of water (design capacity) and the available working pressure is essential to the process of designing a landscape irrigation system. In the past, it would take a lot of time and mathematical calculations to figure out how many heads can be placed on one zone. Now, with new technology, we enter a few numbers when asked, and within moments  have a print-out of the volume of water and the amount of working pressure available for sprinkler operation.

Design Capacity
The design capacity of an irrigation system is the maximum volume of water, in gallons per minute (GPM), available for use in the system. This volume determines how many sprinkler heads can be operated at one time. For instance, if the design capacity of a system is 18 GPM, and you want to specify sprinkler heads that use 3 GPM each, no more than six sprinkler heads could placed on one zone (6 x 3 GPM = 18 GPM).

Working Pressure
The available working pressure, also known as the dynamic pressure, is simply the water pressure at the point of connection, calculated while water is flowing at the design capacity. The dynamic pressure will influence your choice of heads. For example, you would not choose a head with a pressure (PSI) rating that is above the working pressure of the system.