The accuracy of the nozzle spacing can vary quite dramatically depending on where and how your boom was manufactured. Operators should be aware that nozzle spacing might not be what they expect.

Most operators expect that the spacing will be in metric units, often assuming that the spacing is 50 centimetres (0.5 metres). But when they physically measure the spacing they discover it is actually 50.8cm (0.508m), which coincides with a 20-inch spacing (even when the boom width was quoted in metres).

A spacing of 0.508m means that a standard nozzle chart that quotes litres per hectare based on a 50cm (0.5m) spacing will not be accurate: it would include a 1.6 per cent error. If the section width entered into the controller is based on the wrong nozzle spacing, the sprayer output will also be in error.

Tips

• Check the nozzle spacing across each boom section using an accurate tape measure.

• Check the section widths entered into the rate controller.

Section width = number of nozzles per section x the nozzle spacing (metres)

Don’t assume this will be correct when a new sprayer has been delivered.