Preparing knapsacks - spray into spring

Allan Wainwrightin Technical


Knapsack and handheld sprayers both have maintenance demands to keep them operating sweetly. The knapsack sprayer is overlooked as a tool despite its importance in groundscare and it should be part and parcel of any maintenance programme. Allan Wainwright, National Account Manager, Cooper Pegler and Berthoud sprayers explains how we prepare for the new season.

Spraying serves a vital purpose, so why wouldn't you want to maintain kit to high operational standards?

The traditional March to October operational window means sprayers can lay dormant in the shed for several months - plenty of time for innards to seize up and make 2020's first spray a real bugbear.

If you're a grounds professional, who dutifully gave your knapsack sprayers their pre-winter maintenance checks, your kit is likely to be ready and waiting for the new season. It's far easier to prepare for that first outing by conducting best practice before storing sprayers away for winter. Failing that, pre-season maintenance may well pay off. There's nothing more frustrating than finding you have a problem before you even start spraying.

Sprayers often have to survive heavy duty, but we can overlook them when it comes to servicing. I feel this is a major failing and, all too often, sprayers just carry on until they pack up - then the complaints start.

However, regular upkeep and care will reward you with lasting, trouble-free operation for this key kit.

Sprayer choice can depend on what you want to apply and the size of your target area. Knapsack sprayers are designed to take most kinds of groundscare treatment liquids, as are hand-held units, but maintaining crucial parts is essential.

Image right (L-R): piston, outlet and dip tube; piston cup; pumping arm, guides and clamp

Passing my PA1/PA6 has made me further aware of the value of visual checks, but like other groundscare equipment, it's often what you cannot see that is as important as what you can.

That's why a pre-winter (or pre-spring in this case) strip down and maintenance will keep precision parts primed. It's always best to avoid bad habits by getting things right from day one - and you'll rarely spend a more rewarding half-hour.

One customer recently told me he has chalked up twenty years' use of his original Cooper Pegler CP15 Classic diaphragm sprayer. When budgets are tight, why risk needless outlay on cheaper equipment, when quality kit will last ... if it's cared for.

Today's cheap sprayer market is vast, often with few or no spare parts available. The upshot is that too many units end up adding to the waste plastics mountain. You've paid good money for professional quality sprayers designed by professionals - you'll want to maximise their lifetime.

Working closely with the Amenity Forum and Lawn Care Association, I travel the UK and Ireland visiting customers, owners and operators. For them, and those planning to enter the sector, sprayer maintenance forms an increasingly important element of training and development.

Preparing for spring and winter

Why am I talking about winter when we're on the verge of spring? Well, I'll always advise you to prepare for winter, but whatever the time of year, this is your annual maintenance check so it pays to proceed carefully to ensure you pick up any faults.

  • Most sprayers are straightforward to dismantle, but it's best to choose a flat surface like a benchtop to conduct the check. This allows you to lay out everything in an orderly manner, ready for reassembly
  • For the pre-winter maintenance, strip the sprayer down to constituent parts, dismantling to the diaphragm, checking O-rings and all seals for signs of perishing or cracking
  • The type of rubber used depends on the chemicals you're applying and these can vary enormously. Viton resistant seals must be checked for wear to prevent leakage that could damage both operator and environment
  • High-resistant glassfibre reinforced plastic (GRP) lances are vulnerable in a different way. I've known ones be trodden on or driven over and snapped or cracked, so keep them clear of mechanical mishaps
  • Rinsing sprayers thoroughly with clean water after every use is paramount - triple rinsing if you last applied pesticides
  • You can expect most sprayers to run trouble-free from the get-go, but if I do hear of any problems, it's usually after the first or second use and probably resulting from failure to test the product first. Given the number of sprayers we produce annually, the occasional loose screw is bound to occur
  • Sprayer moving parts that come in for most wear and tear include triggers, where constant friction can erode elements. Strip them down gradually, checking each part as you proceed
  • Most trigger includes a filter, so look for any collected debris that will impede functionality and rinse clean
  • Check diaphragms for perishing and splitting and replace if necessary. When reassembling the unit, seals will benefit from a small layer of grease, which aids the process and adds a further protective barrier
  • Once you have rebuilt the unit, and conducted a visual dry check, test for leaks by wet checking - part-filling and pressurising the sprayer with water then triggering to ensure there are no leaks.
  • With typically 15-20l capacity, knapsack sprayers can place a heavy burden on the back. Operator comfort and safety is vital - inspect padded shoulder, waist and chest straps for any signs of wear or fraying as these distribute sprayer weight more evenly over the body.

Image right (from top left clockwise): Pressure setting adjuster with spring and hexagonal-sided fixing screw; clamp ring; pumping handle, crank and guides; diaphragm; dip tube

The National Sprayer Testing Scheme (NSTS) gives clear guidance on keeping sprayers working safely and efficiently.

I provide service labels for operators to stick to sprayer bodies after maintenance checks are completed, which confirm inspection date and who conducted the checks.

Sprayer maintenance is all a matter of commonsense. That said, guidance on how to best conduct regular inspections and the annual winter strip down helps operators and trainers deliver best practice.

My policy is to heighten customer service and support for an aspect of groundscare that needs prioritising. Our presence at trade events and a developing programme of training videos and support material will help that process.

Grounds Training offer a programme of spraying courses including PA1/PA6A and PA2.
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