Senninger Irrigation


What Droplet Size is Best?

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Large, medium and small droplets impacting the surface of water.

Sprinkler manufacturers do not publish the actual droplet dimensions. This would be difficult to measure and would not address what that size really means. Instead, they provide more general droplet information – small, medium, large.

Tighter soils require smaller droplets because they have a lower kinetic energy. However, smaller droplets are susceptible to wind drift, evaporation, and distortion of their distribution pattern. Their overall mass prevents them from traveling far, producing a smaller diameter of coverage, therefore needing closer sprinkler spacing.

Looser soils can accept larger droplets which have a higher kinetic energy. Larger droplets are less likely to be impacted by wind, helping to retain their distribution pattern. They provide a greater distance of throw, producing a larger diameter of coverage, allowing for wider sprinkler spacing.

Flow, pressure, and the deflector configuration determine droplet size. Some sprinklers produce a mixture of small and large droplets. However, this does not prevent soil damage or distortion of the distribution pattern. If a sprinkler produces droplets which are relatively uniform in size, you can select droplets that are suitable for your soil and adequate in size to resist wind distortion. This will help maintain their distribution pattern integrity, thus improving irrigation efficiency and conserving water.

Small droplets are easily affected by wind and their distribution pattern can be distorted.

Larger consistent-sized droplets are less susceptible to wind and help retain their distribution pattern.

For more information about applicators that produce consistent sized droplets, contact Senninger Irrigation at

Low Pressure Irrigation Saves Energy

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Low pressure irrigation translates to reduced horsepower requirements and reduced energy consumption. With rising fuel and electricity costs, low operating pressures offer you a tremendous opportunity to lower total pumping costs. The savings vary depending on your specific system. Hours of operation, flow, pressure, energy source, and cost are all considerations. We at Senninger have a tool available that can provide you with a snapshot of the possible savings based on these considerations. It can be found as a link on our homepage to the Energy Calculator (screenshot shown here).

The Energy Calculator is a tool available online to show you possible energy savings.

If you try to use your older applicators designed for higher pressures at lower pressure, they will produce distorted distribution patterns. They will also deliver droplets that are too large and can have an adverse impact on the soil surface.

Before you select new applicators, you should be sure that they are specifically designed for low pressure operation. If not, they will not provide you with optimum performance. The criteria for low pressure may vary from one manufacturer to another. Typically, low pressure is 20 psi or less. Anything over that is really more of a mid-range applicator.

If applicators are designed for low pressure, they should not be used with high pressures. Otherwise, they can produce water droplets that are susceptible to evaporation and wind drift. For optimum performance, it is best for you to use the manufacturer’s guidelines.

For more information about low pressure applicators and their energy savings, contact Senninger Irrigation at or visit

A sprinkler profile illustrates where water falls in relation to the sprinkler. This is based on flow, pressure, and height. A denso-gram illustrates the distribution uniformity from this information based on spacing.

A single applicator’s uniformity is only part of the picture. The effect of overlapping applicator footprints or, in the case of mechanical move systems, the movement of the applicator, shows the overall distribution uniformity for specific sprinkler spacing. The application rate of these overlapping sprinklers can be tailored to your soil and crop needs. This information is based on no wind perfect world conditions. Actual field performance will vary.

Consider some of the things that impact the uniformity in the real world. Changes in field elevation cause pressure fluctuations. Zones or pivot end guns cycling on and off change pressure. These all alter the flow which impacts the sprinkler uniformity. The use of preset pressure regulators is ideal to overcome these changes to maintain distribution uniformity.

Test the application uniformity of sprinkler layouts before your system is installed. Compares different spacing, sprinkler models, nozzle sizes, and operating pressures to determine which would be best for your specific application.

This image is from our WinSIPP2 software. These terms are used in the image shown:

  • Coefficient of Uniformity (CU): developed before computers, calculates uniformity mathematically. However, it views over- and under-watered areas equally. It doesn’t tell how bad a particular area might be.
  • Distribution Uniformity (DU) looks at over- and under-watered areas differently. It sorts and ranks all data points in the overlap area and uses shading to graphically display it as a denso-gram. The wettest area is darkest and the driest is white. All other wetted values fall between with corresponding shaded values.
  • Scheduling Coefficient (SC), developed by CIT (Center for Irrigation Technology) provides a way to measure uniformity. It uses a sliding window to analyze sections of the sprinkler pattern. It calculates the ratio of lowest and highest values to determine the run time of the application needed to water the driest areas. An SC close to 1 is good.
  • Application Rate is the amount of water applied. This is often shown in inches per hour. This must match your soil’s intake rate. 

For more information about sprinkler uniformity, contact Senninger Irrigation at or visit

How Does a Pressure Regulator Work?


A pressure regulator limits excess inlet water pressure to a constant outlet pressure. You need constant outlet pressure to ensure that your sprinkler (or emitter) performs well.

Water travels through the inlet end of the regulator and around a fixed seat into the critical flow area. The water then enters into a hollow cylinder called a throttling stem (or T-stem) which is attached to a larger diaphragm near the outlet end. A spring around the throttling stem tends to hold the flow area open, while water pressure acting on the total diaphragm area tries to close it. This duel always ends in a draw with the outlet (or regulated) pressure being determined by the spring’s compressive strength.

What does this mean to you?

Your sprinklers can only pass along what they receive. Give them consistency and they’ll return the favor. Most sprinklers perform best at a specific pressure level, often lower than your in-line pressure. But in-line pressure should be at least 5 psi (0.34 bar) higher than your regulator’s designed outlet pressure.

A regulator’s design and the materials used to manufacture it greatly impact its accuracy. Be sure to choose the regulator model that best fits the flow and pressure required for your application.

Senninger introduced the first quality in-line pressure regulator to the irrigation industry in 1966. Our regulators are 100% water-tested for accuracy and have a two-year warranty on materials, workmanship, and performance.

For more information about pressure regulators, contact Senninger Irrigation at or visit

LEPA (Low Energy Precise Application) irrigation was developed in the early 1980’s. It was to meet the needs of the declining aquifer levels in the western high plains of the United States. Today, LEPA continues to deliver significant water and energy savings worldwide.

In true LEPA systems, applicators are positioned to deposit water into every other furrow. This requires planting in circles for center pivots and straight rows for linear machines. Heat accumulates in the dry areas and keeps the plant warmer. The plants share the water in the furrow in between. This keeps the crop canopy dry and prevents possible damage from salt in the water. Because water application is close to the soil, LEPA is 95% efficient in water use and requires very low pressure – 6 to 10 psi (0.41 to 0.69 bar). This saves energy and conserves water.

LEPA systems must include furrow dikes or crop residue to hold water in the rows near the plant until the soil can absorb it. LEPA irrigation works best on farms with a flat terrain and relatively sandy or loamy soil where runoff is not as likely as in heavier, tighter soils or sloping terrains.

We introduced our Quad Spray in 1986 specifically for LEPA irrigation. This sprinkler provides four different ways to apply water based on crop need. A simple twist changes this applicator to deliver one of four modes: two different bubble modes that irrigate directly into the furrow, a spray mode for germination, or a chemigation mode to wash the underside of the crop canopy. Other LEPA products include our LDN with a bubbler pad or drag hose adapter, and our Super Spray with a drag hose adapter.


Senninger Irrigation

Senninger Irrigation
A Hunter Industries Company
16220 East Highway 50
Clermont, FL 34711

Office: (407) 877-5655

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Senninger Irrigation