Whilst demonstrating the value of good sprayer set-up and particularly nozzle set-up last week, I had a quick look at the pressure gauge on one of the sprayers at the course I was at. I was a little surprised to how the different pressures were indicated on the dial.
I suspect that if the manufacturer was asked they would say the dial colours will indicate the pressure tolerance of the sprayer not a recommendation for nozzle pressure.
On all nozzles there will be an optimum pressure range. Below shows the Syngenta XC 025 nozzles with an optimum range of 2 to 4 bar. Personally I'd lower that still and try to stay in the lower half of an optimum pressure range to ensure the very best cover and maximum efficacy.
When you transpose this info over to the pressure gauges they look very different.
Auto-rate sprayers are particularly prone to this - whilst they can quickly vary the speed and adjust the pressure accordingly. This will very quickly adjust the way the nozzle works which in turn will move it away from it's most effective range.
The video below shows how a 0 - 5 bar range is clearly unacceptable. 0 Bar is obviously not going to work and anything above 4 can cause dramatic losses to drift.
Unfortunately this is something I see quite often - take the time to check out the optimum pressure range for your nozzles and mark it in your pressure dial.
