Infrastructure

Pipes

Sizes must suit the length and area to be sprinkled, the number of sprinklers and their flow rates. Here is a guide:

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 50 m runs of 25 mm

PVC piping does not twist, but polythene 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.

3.

Controller / timer

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 one to three minutes, which should be sufficient to wet them effectively, and then shut off for the remainder of each 15-minute cycle to allow the water to evaporate before the next cycle.

4.

Temperature sensor

Temperature sensors can also be attached to the controller to allow sprinklers to automatically switch on when cows are in the dairy yard at a certain temperature, for example, at 25°C.

(Note: if an automated system is installed, ensure you can manually override it if necessary).

5.

Pressure regulators

Low-pressure sprinklers work best (0.70 kg/cm2), producing larger droplets, less mist and drift of spray (Large 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).

A main pressure regulator can be installed at the beginning of the pipeline or smaller regulators on each sprinkler nozzle can be used.

Operating pressures are usually in the range of 14 to 20 m (140-200 kPa).

Low pressure will produce larger droplets and less mist and drift of spray.

6.

Filter

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.

A common filter type is a plastic filter with a grooved disc filter element. A 200 micron filter is used for spray cooling and an 80 micron filter for drip cooling.

Filters should be capable of a flow rate of up to 1.4 litres/second for spray and 0.8 for drippers.

7.

Water

Ideal water temperature is 15-20°C (Note: providing cows with chilled water at the dairy to help reduce heat load may reduce water intake and therefore be counter-productive).

Water containing more than 1000 mg/L TDS (total dissolved solids) should not be used in reticulation systems because of corrosion (dissolves concrete!)

An allowance of 0.5-1 litre/head/hour is common for spray cooling dairy cows.

Remember that excess water use will create waste management issues.

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