Sprinkler System Design

Sprinkler nozzles

Sprinklers can be effective in enhancing evaporative cooling.  Their effectiveness will be lost when humidity is high and airflow is low. 

Combined with good infrastructure to maintain airflow and using on-off timing to allow humidity to drop will maximise the effectiveness of sprinklers. 

There are several sprinkler nozzle types that will adapt to your desired use, location, area and droplet size.

 
Type Benefit Limitation 
 Large irrigation sprinklers Can wet a large area High water use

 Overhead wobbler sprinklers

Use less water   Do not throw water as far
 Garden sprinklers Use less water, also suitable for overhead use Can be ineffective in windy conditions

Design tips

  • Droplets must be medium-large to allow water to penetrate the hair coat and wet the cow's skin.
  • Best position depends on type and capability of selected sprinkler and pumping system.
  • However, as a guide, sprinklers should be spaced at intervals of 1.5 to 2 times their wetted radius, so there is a slight overlap of wetted areas.
  • Sprinklers should be set at least 2 m above the floor of the dairy yard.

Pipes

Sizes must suit the length and area to be sprinkled, the number of sprinklers and their flow rates.

 Shed length Diameter of main delivery line
Up to 40 m 20 mm

40 - 60 m

25 mm
60 - 100 m 32 mm
 More than 100 m 2 x 50m runs of 20mm
Design tips

  • PVC piping does not twist, but polyethylene (PE) is cheaper.

  • To maintain low water temperatures, all exposed pipe should be painted white and header tanks should also be shrouded, insulated and painted white.
  • There are also some newly developed paints that have reflective properties that are worth investigation for their appropriateness for the chosen material.

Sprinkler diagram

Ideal sprinkler system settings

Ideal State Consideration
Water temperature

Temperature range: 15-20°C

Providing cows with chilled water at the dairy to help reduce heat load may reduce water intake and therefore be counter-productive.
Temperature sensors: Automatic If an automated system is installed, ensure you can manually override it if necessary.
 Water quality 
 Total dissolved solids (TDS): No more than 1000 mg/L TDS High dissolved solids used in reticulation systems are corrosive and dissolve concrete.

 Water output rate: 0.5-1 litre/head/hour

Excess water use will create waste management issues.

 Design Note: For more complex or larger installations it is necessary to properly design the system taking into account friction losses, flow rates and component selection.
 

Pressure range

 
 Low Pressure: 0.70 kg/cm2 Produces larger droplets, less mist and drift of spray.
 Operating Pressure: 14 to 20 m (140-200 kPa). A main pressure regulator can be installed at the beginning of the pipeline or smaller regulators on each sprinkler nozzle can be used.
 Design NoteLarge droplets penetrate the coat better. Smaller droplets can create an insulating layer of water on the cow's coat that can make the cow hotter instead of cooler droplets are required, not mist
 

Filters and rates

 
 Drip cooling system  
 

Filter: 80 micron

Rate: 0.8 litres/second

Sand or dirt may clog the sprinkler nozzles, so a filter is required between the water supply and solenoid valves that control the water flow to the spray nozzles or drip outlets.
 Spray cooling system  
 

Filter: 200 micron

Rate: 1.6litres/second

A common filter type is a plastic filter with a grooved disc filter element.
Usage advice on timers

A 15-minute adjustable type timer, attached to remote control valve (solenoid) will enable you to apply sufficient water on cows while minimising wastage.

Aim to sprinkle cows for 1-3 minutes, which should be sufficient to wet them effectively. Then shut off for the remainder of each 15-minute cycle to allow  water to evaporate before the next cycle.