27 February 1998

Is your sprayer up to test?

As with cars, putting a

sprayer through an "MOT"

can be a revealing

experience. Andy Collings

went to see how the sprayer

used by farmers weeklys

Easton Lodge farm fared

during a recent test

TESTS for sprayers is a relatively new concept for British farmers, although in several other European countries similar schemes have been mandatory for some time.

Endorsed by the Agricultural Engineers Association (AEA), the voluntary UK biennial test is performed in very much the same way as an MOT for a car. A list of items is checked with the examiner ticking a pass or fail box alongside, with view to rectifying any problems that occur.

But why have a test? Bearing in mind the high cost of pesticides – and the publics acute awareness of the use of such products – it clearly makes sense to ensure a sprayer is maintained in good working order.

It is a message not lost on farmers weeklys farms manager John Lambkin who decided to put his three-year-old Knight sprayer through an AEA sprayer test. With Knights premises only a few miles down the road from Lincs-based Easton Lodge farm, operator David Cham took the machine directly to the companys on-site test centre.

"This is the first year weve offered a testing service of this type," explains Knights service manager, John Wooding who reckons his company will carry out about 30 sprayer tests this spring.

"Fair to say that the sprayers weve tested tend to be from farms where maintenance standards are pretty high," he says. "It is those machines which are not looked after that we should be looking at – but thats the way of a voluntary scheme."

&#42 The test

Easton Lodges sprayer is a 1000-litre (220gal) mounted machine with 20m (65.5ft) booms. Purchased in Sept 1994, it is used, in conjunction with a 2000-litre (440gal) front mounted tank, to apply pesticides to the farms wheat, sugar beet, peas and oilseed rape crops.

The first group of test items came under the heading of mechanical safety and, with the exception of a missing restraining chain for the PTO cover, all was deemed to be well.

Then it was an inspection of the hydraulic system for leaking pipes and joints, the electrics and whether tap labels were in place. Onto the tank and a check for leakages and to note whether the contents gauge was legible – it was discovered that the tank sump plug was leaking.

A move round to the boom and a check for straightness, height adjustment, break back and its ability to return to level after being pushed down 30cm (12in) on one end. On this latter point, tightness on the main pivot prevented a satisfactory result.

Now to test the sprayers delivery system. With a tankful of water the pump is set in motion and the pressure run up to 5 bars to see if there were any leaks. This was followed by a check on the on/off controls and pressure compensation when a section is shut off.

The sprayers pressure gauge – a key part of the machine – came in for heavy scrutiny. Removed from the sprayer it was tested for accuracy against a master gauge.

With all well in that department it was time to test whether the pressure at the middle of the boom was the same as that shown on the gauge. A discrepancy of 0.1 bar was detected – a difference well within the 10% tolerance allowed. Further pressure tests on different spray sections confirmed that this discrepancy was consistent along the length of the boom.

And so to test the flow rate from the nozzles themselves. Stopwatch in one hand and measuring jug in the other, Mr Wooding took a total of eight readings, with all producing a flow rate within a 10% tolerance.

Surprisingly, there was no test to determine whether the pattern produced by the nozzles was correct although, to be fair, this would have required the use of a paternator which is not currently in Knights test kit.

A final check for the chemical induction system, the tanks rinse system and an RDS application control system, and the test was concluded.

&#42 The verdict

Four faults were found – none of them too serious. A washer on the sump plug needed to be replaced, a chain was fitted to the pto guard, the rinse spinner in the tank needed freeing off as did the main pivot bearing for the booms.

&#42 The cost

The basic fee for the test comprises an £18 payment to the AEA for administrative purposes and the cost of two hours labour to Knight – a total of about £55. The cost of parts and labour for any work performed needs also taking into account, as does travelling time if the test is performed on the farm.n

Knights service manager, John Wooding, makes some initial notes before putting Easton Lodges sprayer through its AEA test.

John Wooding checks the flow rate of a number of nozzles to ensure application rate is even across the length of the boom.

All well here – the sprayers gauge reads the same as the master test gauge.