Machinery Focus: Getting prepped for the sprayer test


Written by Justin Roberts

A sprayer, especially on a non tillage farm, is often neglected until required. This can result in poor, or even hazardous, operation when they are eventually pulled from the hedge and pressed into work.

The use of pesticides is already a target of public criticism and censure. In a bid to counter this pressure from the environmental lobby, the EU has adopted a stance of ensuring that those chemicals which are applied, are done so in a safe and responsible manner, through training operators and licensing equipment for use.

Test base
Sprayer should be mounted on the tractor used for spraying and parked on clean, level and well drained ground

Sprayer tests

As part of this initiative, the Irish government was obliged to introduce a system of testing crop sprayers in 2015.

The legislation applies to all sprayers over five years old and more than 3m in width.

It also apples to orchard misters and weed wipers, although it is the standard boom type crop sprayer we look at here.

Handwash on sprayer
Any peripheral items on the sprayer, such as handwash unit or toolbox, need to be in good order and firmly attached

The test must be conducted every three years by an approved agricultural equipment inspector, who has the responsibility of ensuring the machine is safe to use and does not constitute an environmental hazard due to leakages or incorrect application rates.

Jim Dockery of Farm Relief Services (FRS) is one such inspector and here he guides us through the items that are examined on a sprayer to allow its continued use.

As with all inspections, a report is generated and this is then lodged online, with the Department of Agriculture, Food and the Marine (DAFM).

However, it is not simply a matter of a pass or fail on the spot, the inspector can guide the farmer and work towards getting it through the test.

Jim’s first task is to identify the sprayer and pump, and these are recorded along with the type, capacity and working width of the unit.

These are all noted before moving on to the equipment itself, and here the primary item is the safe condition of the PTO shaft. Click on the below images to enlarge and scroll across.

  • PTO
    The first step is to check the PTO guard is fully attached and chain is in place
  • Sprayer chassis number
    The sprayer frame will need a legible manufacturer’s plate with model and serial number
  • Pump number
    A manufacturer’s plate on the pump will give date, serial number and pumping capacity

The general state of repair is also noted with any damage or leaks being noted and highlighted for attention.

The presence of drips and puddles, along with ‘wonky’ booms are a definite red flag and will need to be rectified before a certificate can be issued.

Constant pressure

Main Sprayer gauge
The main pressure gauge must be fitted downstream of its filter and be accurate to within 10% of a calibrated master gauge

The key to accurate application of a chemical is the maintenance of an unvarying and uniform pressure throughout the system.

A large part of the examination is dedicated to ensuring that this happy state is achieved and maintained. The main gauge and cleanliness of the various filters being of particular importance.

  • Pulsation damper
    On a reciprocating pump the pulsations are usually damped by a silicone diaphragm with a pressure of 1 bar set on the outside

Not only must the pressure being delivered to the the spray lines be equal, but there must a minimal pressure drop between the valves and the boom.

Neither must the pressure drop along the the spray lines themselves be greater than 10%

  • Master gauge sprayer
    The sprayer’s pressure gauge is checked against an annually calibrated master gauge (left)
  • Pressure drop sprayer
    A gauge fitted at either end of a spray line checks for pressure drop along its length & must not exceed 10%
  • Gauge clamp on sprayer
    The line pressure gauge may be attached directly to the nozzle mount, or clamped directly to the nozzle

The function of the controls will be checked, with particular emphasis being on the immediate shut off of the sprayer.

All nozzles must stop spraying and dripping within five seconds of the main valve being closed. Should they continue to drip, then the culprit is often a split diaphragm in the cut-off valve at the nozzle.

  • Nozzle type
    Nozzles are colour coded to indicate flow rate. Each set of nozzles need to be tested separately
  • Nozzle stop valve
    Dripping nozzles are often caused by a damaged check valve diaphragm (bottom left)
  • Nozzle filter
    The final filter in the system usually sits above the nozzle. It will need to be cleaned before the test

Flow rate

Having examined the components responsible for delivering the spray to the nozzles, these final items must also be checked.

The flow rate for each set that is in use, must be tested on a separate basis. This can be a long and arduous job, that is much relieved by the advent of digital flow meters.

  • Flow rate test
    Checking the flow rate from each nozzle is now performed by a meter rather than cylinder and stopwatch
  • Height
    Checking the boom height. The nozzle tip should be between 70 – 75cm above the crop canopy
  • Nozzle gap.
    The spacing between nozzles must remain at 50cm. Pipes may become loose causing this to vary at the pivot points of the boom sections

Having recorded all the information, it is uploaded to the department’s website which automatically works out the deviation of flow rate and coefficient of variation.

If either of these are above 10%, the sprayer will fail. However, Jim notes that such problems are usually noticeable during the test and can be sorted out before the final figures are entered.

Ongoing care for your sprayer

Once compliance is achieved, Jim suggests the best way of ensuring it stays serviceable, is to simply use it.

Making sure it is well drained before putting it away is also essential and it may be necessary to disconnect hoses and filters to do so.

Extremes of heat and direct sunlight can also take their toll, so keeping it in a shed over winter is highly recommended.

There is no reason why a well maintained and lightly used sprayer should not last for many years. A regular check up is an essential part of keeping it going.

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