Originally posted January 2011.
There are two types of sprinkler models used for center pivot and linear equipment: fixed spray and rotating spray. Both sprinkler types have a wear plate mounted directly below the nozzle (orifice), which discharges the water and creates a 360° water pattern. Fixed sprays have no moving parts because the wear plate is fixed. A rotating spray wear plate rotates either fast or slow, depending on the sprinkler model.
Water Patterns and Runoff
Rotating sprays produce a large wetted diameter (50' to 70') that creates a low-intensity water pattern; this is a major advantage of rotating sprays. This type of sprinkler works very well on medium to heavy soil types and reduces water runoff. Fixed sprays have a wetted diameter of 15' to 40'. This type of sprinkler works well on light soils where runoff may not be a big issue.
There are a variety of plate designs available to you that can very the droplet size of the water pattern; various designs are available for both rotating and fixed sprinkler types. By selecting a plate that produces smaller water droplets, you can also reduce the water pattern intensity. Smaller water droplets can easily lead to lower application efficiencies from evaporation and wind drift losses. Please note that climate conditions must be considered in the plate selection.
Fixed spray and rotating spray sprinklers are designed to operate at a low pressure in order to minimize energy (pumping) costs. Design operating pressure for fixed sprays is 6 to 30 PSI and pressure for rotating sprays is 10 to 30 PSI.
Learn more about sprinklers and other water application technology for center pivots and linears on valleyirrigation.com!