Farm Ireland
Independent.ie

Monday 27 February 2017

Spray some attention to maintenance

As the rush starts to establish crops, avoid big problems by finding time to service the sprayer

Bruce Lett

The sprayer should be cleaned out and all nozzles rechecked before deciding whether or not to replace them. Any nozzles with streaks not caused by dirt should be replaced with new ones
The sprayer should be cleaned out and all nozzles rechecked before deciding whether or not to replace them. Any nozzles with streaks not caused by dirt should be replaced with new ones

As the days lengthen and the weather warms up, we are again entering what is perhaps one of the busiest periods in the farming calendar, with farmers and contractors rushing to establish cereal, maize and potato crops.

An integral part of managing these crops is the application of herbicides, insecticides, fungicides and liquid fertilisers.

All of us are acutely aware of the cost of these chemicals and in an attempt to ensure the desired amount of chemical is applied in the correct manner, we visited Teagasc's sprayer specialist Tom Ryan in Kildalton. Tom and his retired colleague Bernard Rice have accumulated a wealth of advice and information on sprayers and spraying over the years.

More recently Teagasc carried out a survey of 14 crop sprayers to check their general condition and their ability to apply pesticides accurately.

None of the sprayers were idle as, according to the report, the 14 sprayers covered almost 3,000ha a year -- four times the average. The following is one of the actual reports on a sprayer surveyed at the time and many may find the checklist section of the report (see table, left) useful as a guide to performing checks on their own sprayer. Mr Ryan compiled the results, which make for some interesting reading.

Survey Results

  • Forward speed

Forward speed that the sprayers were operated at ranged from 8km/hr to 11.5km/hr. The speed read-out for 12 of the sprayers was equal or almost equal to what was indicated on the tractor's own speedometer, while one sprayer was 1.4km/hr and another 1km/hr faster than indicated in the cab.

  • Pressure gauges

The table (above) shows the results of the pressure gauge tests with regard to gauge error, reading zero when stopped and glycerine level.

Also Read


Generally, gauge error should normally be less than 0.2bar. Pressure gauges are delicate and can be damaged by excessive pressure.

Frost this year caused problems with a lot of pressure gauges, leaving them reading well above zero when stopped. Some gauges were not easy to read because they were too small or the scale had too big a range, or both.

Gauge accuracy can be checked by temporarily attaching a second gauge, known to be accurate and comparing the sprayer gauge to it.

Another way is to use a few new nozzles to relate outputs to gauge pressure based on nozzle chart values.

  • Nozzle outputs

A summary of the nozzle output measurements is presented in the table on the opposite page. Nozzles on six sprayers are clearly in good condition with little or no wear. These sprayers are numbers 2, 8, 9, 10, 11 and 13. A few nozzles are a little dirty, which when cleaned will improve results.

A further five sprayers (numbers one, three, four, seven and 12) are indicating signs of nozzle wear.

However, there is a lot of variation in the outputs from sprayers one, three, seven and 12, so these should be cleaned and rechecked, although the average output is then likely to increase, indicating even more wear.

The recommendation in that case is to replace them with a new set. Sprayer four has no variation but shows wear. It should be rechecked during this season.

Sprayer number 14 needs to be rechecked. There is little variation and it seems there is a gauge error, a nozzle identification problem or some other error made during the test.

There is a big variation between nozzle outputs with sprayer number five, although the difference above the rated output is small.

The sprayer should be cleaned out and all rechecked before deciding whether or not to replace the nozzles.

In hindsight, it would have been better to have the sprayers and nozzles perfectly clean and have all leaks sealed before the nozzle tests. Any nozzles with streaks not caused by dirt should be replaced with new ones anyway.

The nozzle output of the other sets of nozzles on the boom should also be checked.

  • Filtering

There were problems with filtering. Many of the sprayers weren't cleaned out before the check-up. We didn't ask for them to be cleaned for the test. As it happens, many of the sprayers were not serviced since last season.

It did indicate that filtering may not be adequate on some sprayers and that some products can cause more problems than others with regard to mixing and filtering. Some operators also are not as thorough as they should be when it comes to filtering and cleaning.

Some operators mentioned that frost and the use of some spray chemicals loosened scaled-on dirt within the sprayer, which led to blockages in the nozzle filters.

  • Other findings

Generally, the outsides of the sprayers were very clean. The insides of spray tanks were also clean. Some basket filters showed evidence of chemical, which indicates that basket filters are being used to fill in the chemicals instead of the low-level induction bowels.

Four sprayers had holes or faulty gaskets on tank lids. Three sprayers had leaks at suction and pressure filters.

Most booms are in good condition. Isolated problems, such as sagging, stiff break-back devices, hoses in the spray pattern, were seen. Boom folding and suspension systems were good. Of the two air-sleeve sprayers, one air sleeve needs replacing.

  • Safety

Safety issues were not recorded. However, there were problems on some of the sprayers and tractors with PTO shaft guards and reflectors and lights.

Some other safety features not checked were hitches, three-point linkages, and wheels, tyres and brakes. Some access ladders were faulty.

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