Ei Operator

Essential information for Sprayer Operators

Equipment

Knapsack Know-How

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knapsack sprayer, nozzle head

Get a handle on knapsacks

Just as for larger applicators, when using hand held sprayers, correct applicator selection and maintenance, along with operator training are all crucial to ensure applications are undertaken efficiently and legally.

man with a knapsack spraying device

Operator training

All operators must have achieved an appropriate certificate of competence in the use of pesticides.

For those using hand-held applicators PA1 and a PA6 qualification is required. Operators should check they have completed the correct units from the PA6 suite for the applicator being used, eg stem injectors.

Testing and maintenance

Hand-held applicators are exempt from the Sustainable Use Directive (SUD) testing requirements. However, all hand-held equipment must be inspected regularly for condition and a record of checks and maintenance kept. A useful checklist is available here

The National Register of Sprayer Operators (NRoSO)  have also produced a useful video in which you can follow the simple steps for pre-use checks.

Measuring and filling

Essential to best practice, is knowing how to measure the correct product and add it to the knapsack. In this video, NRoSO carefully explain the steps to follow and how to deal with minor spillages. Always follow best practice and product label guidelines.

Hardi knapsack sprayer

Using a knapsack

The changeable nozzle on knapsack sprayers provides the flexibility to achieve flow rates (litres/min), spray patterns and qualities to apply a wide range of products.

All knapsack sprayers should have some form of built-in pressure regulation, to ensure a constant liquid flow rate. This constant pressure will help ensure the application rate and spray quality required on the product label is achieved. However, for the professional operator repeating the walking speed used in the calibration exercise is critical to achieving consistent target application rates.

Correctly calibrating applicators is a requirement under the Code of Practice for Using Plant Protection Products, which you can find HERE.

Operators must regularly undertake the calibration exercise to check their walking speeds. They should never assume their walking speed, because it can vary according to the surface being sprayed and weight of applicator.

To achieve target application rates throughout treatments the selection of a sprayer with a type and size of pump that minimises operator fatigue will aid consistency. In general, to achieve a given flow rate, diaphragm pump sprayers will require more lever cycles than an equivalent piston pump.

The larger the pump, the fewer pump cycles required to achieve the target flow rate and with less operator fatigue.

To aid your decision making, watch the following video about preparation for calibration.

Berthoud knapsack spraying device

Knapsack choice

Aim to select a unit that complies with the international standard on backpack sprayers (ISO 19932) to ensure sufficient durability to prevent harmful leaks or spills. Many knapsacks sold in the UK will not meet this standard -particularly those in the DIY market.

Weed control devices

Alternatives to a knapsack sprayer are now available for professional operators to apply certain herbicides, often to specific weeds.

Most of these units are easier to set up than a knapsack sprayer because calibration is minimal and applications are often independent of forward speed. They are especially useful to apply spot treatments of non-selective products to control weeds where any surrounding vegetation is not a target.

Many are also able to deliver applications without drift potential, and some can even apply treatments by closed transfer to the target plants, such as stem injectors or pesticide plugs for the prevention of regrowth from cut stumps. This reduced drift potential is not only beneficial from an environmental perspective, but it can also help reduce the chance of operator contamination.

knapsack sprayer with boom head

Nozzle selection

Nozzle choice is an important step in ensuring spraying efficacy.

The NRoSO video below will help you make the right choice when it comes to selecting the correct nozzle for a knapsack spraying device.

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Top tips to pass NSTS test first time

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Pesticide application equipment working on UK farms must now be checked by the National Sprayer Testing Scheme. The good news is nearly half of the sprayers inspected exhibit no faults, but that still leaves the other half requiring repairs before they receive a certificate.

It is now a legal requirement that all boom sprayers over 3m wide and more than five years old on 26th November 2016, must be tested and retested within five years up to 2020. Non-compliance could lead to prosecution and threaten single farm payments.

Sprayers less than five years old on 26th November 2016, must be tested by their fifth anniversary. They must be retested within five years up to 2020 and after that date all sprayers must be tested every three years.

sprayer being checked for the NSTS test

Machines with booms less than 3m wide are required to be tested every six years, after the machine is five years old. The same applies to other machines including, for example, granular and slug pellet applicators, weed wipers and seed treatment units.

It is important to note, however, that many crop assurance schemes demand that sprayers, pesticide and nematicide applicators are tested annually, irrespective of the legal obligations.

The National Sprayer Testing Scheme (NSTS), which now includes granular and slug pellet applicators, as well as fogging machines, checks more than 20,000 machines every year.

NRoSO registered operators can gain three CPD points from attending the test by simply having the test engineer sign an attendance form. This also includes an operator check list, which is not only useful to prepare machines for the test, but also serves as a helpful memory jogger for routine maintenance.

To download a PDF of the NRoSO record sheet, click HERE   and the check list can be downloaded HERE

NSTS and test engineers are concerned machines are being presented with the same top ten faults every year. These are not difficult or costly problems, which really should be picked up and fixed during operation to ensure effective and safe operation.

NSTS top ten fails

  1. Filters – blocked or damaged
  2. Leaks – over normal working pressure
  3. Contents gauge illegible
  4. Leaking anti-drip device or drip control valve  (DCV)
  5. Worn nozzles
  6. Inaccurate pressure gauge
  7. Illegible control labels
  8. Section controls
  9. Damaged or faulty guards
  10. Pressure gauge scale and gradations

1: Filters

blocked filter on sprayer

Damaged or blocked filters are still the most common faults found on test candidates. This will be due to lack of thorough or proper cleaning, which results in two issues: First the residues in the filter can come into contact with an incompatible chemical and cause a bad reaction. Second: If the residues come off during operation they will cause nozzle blockages and can also affect the operating pressure.

2. Leaks over normal working pressure

Leaking hose under pressure

Pressure leaks should be obvious and often clear to see when the system is operating under normal pressure, which operators should easily spot. The test requires the machine to be run at 2 bar above the standard working pressure – usually 5 bar. This will reveal problems not apparent during normal work usually leaks from loose pipe clips, joints and joiners.

3: Illegible sight tube

Illegible markings on a tube

An illegible sight tube, that prevents operators seeing the tank contents is the third most common NSTS fault. The actual scale needs to be in good condition and readable. While pendimethalin staining is the most common culprit, tubes do become cloudy through age and exposure to sunlight. Dry sight tubes and electronic gauges must also register the actual tank contents.

4. Leaking drip control valves

A leaking Drip Control Valve

A leaking anti-drip device, or Drip Control Valve (DCV) is another very common fault. The diaphragm and spring in the valve are wearing parts and need to be regularly cleaned and checked for leaks. Depending on annual use, it’s a good idea to change these every year. Worn DCVs will drip when the machine is switched off and need to be fixed to prevent pollution.

5: Worn or damaged nozzles

Operators should regularly use a jug test to check nozzle outputs, but worn or damaged nozzles still account for a high proportion of NSTS fails. In the test the acceptable standard is 10% and the NSTS requires a minimum of one nozzle on each boom section to be tested. It also stipulates if one nozzle is found to fail the whole set must be replaced.

6: Inaccurate pressure gauge

Faulty pressure gauge on a sprayer

There can be few operators that don’t look at their pressure gauge, but many in the NSTS tests are found to be faulty providing inaccurate readings. Gauges do wear and show incorrect readings and those that do not point to zero when there is no pressure in the system are not working correctly. Frost damage can often lead to issues. Some operators remove gauges at the end of the season, or even after every spray session to reduce the likelihood of problems occurring.

7: Illegible control labels

Illegible control labels on a sprayer

Control labelling comes under scrutiny in the test, which says they must be complete and legible. As machines age and after numerous wash downs many lose their labels, increasing the risk of making mistakes when filling, mixing and during application. Home-made replacements are fine, such as using permanent marker – provided they are clear and readable.

8. Section controls

section controls on a sprayer

Test engineers check the boom section on/off functions are working correctly. They also check the pressure in each section to ensure it is uniform pressure across the whole width. When boom compensation returns are fitted, these are checked to ensure the pressure stays the same when sections are turned on/off.

9: Damaged or faulty guards

A damaged guard on a sprayer

Machines presented for testing with a damaged or faulty PTO guard will not be tested until it is replaced or repaired. It is surprising, say some engineers, how often they find damaged PTO guards, because these should be put right immediately as it not only puts lives at risk, but is also breaking the law. The test cannot proceed if the PTO guard is missing or damaged which means that the tester will have to come back for a second time.

10: Pressure gauge scale and graduations

A damaged pressure gauge

Pressure gauges make it into the top ten faults for the second time with problems concerning damaged or unreadable scales, which are now mandatory checks. The scale must be readable from the operator’s position, be a minimum 63mm in diameter and have maximum 0.2 bar graduations.

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