The UK market is awash with numerous spray can shapes, volumes and neck sizes, says Clive Brookman of Beds-based spray tank manufacturer Watson & Brookman.

“And that’s a big issue if you’re trying to make a washer unit that can cope with the majority of container designs,” he explains.

Watson & Brookman, best known as a supplier of stainless steel tanks to UK sprayer manufacturers, has been looking at expanding its product range, but demand for a washer unit was unknown.

“We took a prototype to this year’s Cereals event as a talking point, but ended up with producers trying to buy it.

We weren’t in a position to let that happen – the problem being the difficulty in designing a unit that can cope with a range of currently used containers,” he says.

Spray cans vary in size from one to 20-litre packs, with neck openings from 35mm to over 60mm in diameter – a major factor in allowing any rinsing agent to drain from the container during a wash cycle.

“It would be simpler if there were fewer pack sizes to accommodate, we could pin down the design,” adds Mr Brookman.

Why the sudden rush of interest?

In July this year new Waste Management Controls were introduced to agriculture. Included is a requirement for farms to recycle and dispose of waste plastics in a controlled manner.

Burying and burning on-farm – a common route for disposing of spray cans – will be banned as early as December this year, according to DEFRA.

That presents growers with a problem, how to dispose of these waste items?

Although some collection schemes have begun (see FW Sept 9, p68), these require cans to be thoroughly washed to remove chemical residue before collection.

Mr Brookman reckons spray manufacturers have done little to help farmers address the issue and feels that this is likely to continue.

Spray chemical suppliers believe a standard range of containers to be used across the board is highly unlikely.

BASF – one of the largest suppliers – suggests it is standardising its range across the EU, but not in conjunction with competitors.

Syngenta also suggests it is making changes within its own range, and, like a number of other suppliers, is moving towards wider neck openings.

A solution may not be immediately forthcoming.

“That’s about the mark,” says researcher Simon Woods of Harper Adams University College, Shropshire, who – along with colleague Simon Cooper – has undertaken a study of spray can washing faults.

Speaking to growers at a Spray Waste Management event at the college earlier this year, Dr Woods explained that the operation was often fraught with difficulties.

“Sometimes the containers won’t fit into the induction hopper – where many are currently rinsed – or can design doesn’t allow effective cleaning, such as hollow handles that allow spray residue to escape washer jets.

There is a long way to go yet,” he said.

Rinsing a spray can in an induction hopper on a sprayer is still the most common route ahead of disposal, says Barrie Cotter, production manager with Norfolk-based sprayer manufacturer, Sands.

Like other manufacturers, the company uses a rotating water jet to improve rinse capability of induction systems.

“This is a new, effective jet for rinsing inside cans, by rights the outside shouldn’t need washing – there should be no chemical spilt,” says Mr Cotter.

But Mr Brookman feels a full internal and external rinse system would be welcomed by growers.

“That’s what created the interested at Cereals.

“Now whether that is a stand-alone unit that can be connected to an induction system to remove washings or a unit fitted on to the sprayer itself remains to be seen.”

There is no apparent single solution.

Ironically, sprayer manufacturers are alive to user feedback and if induction hopper rinsers don’t suffice, then they may turn to their main tank spray line supplier to suggest a solution.

Any progress is likely to be grower led rather than chemical manufacturer led.

fwmachinery@rbi.co.uk