Application Technology : Care and Use of Equipment
Excerpt from 2010-2011 Publication 75, Guide to Weed Control, Order this publication Table of Contents
Spraying SpeedsBecause most agricultural and roadside herbicide must be uniformly
applied, the forward speed of a sprayer must be constant whenever
the nozzles are delivering liquid. If the driving wheels of a tractor
slip on the soil surface, the tractor’s speedometer does not
indicate a change in forward speed. To be certain that the forward
speed is constant in spite of wheel slippage on hills, or WaterUse only clean water that contains no debris, sand or mud. On your farm water supply, use a frost-free water hydrant located outside a building. An anti-backflow or anti-siphon valve should always be installed on any hydrant or water supply. Never allow the intake screen to rest on the bottom of a farm pond while filling a sprayer. The intake line near the screen must, by law, be equipped with a check valve or anti-backflow device to prevent contamination of the pond or stream when the pump is shut off. Tank-refilling nozzles, volumebooster nozzle or injection pumps should not be used to refill the sprayer tank from farm ponds or streams. These tank-refilling aids may cause pond or stream contamination. AgitationWhen chemical formulations in solution are used (e.g. 2,4-D and
water) at least 2–14 L of spray solution should be returned
to the tank each minute to provide adequate agitation. Higher rates
will apply with wettable powders. To be effective, the agitation
line from the pump should pass through a control valve and deliver
the liquid to the bottom (not the top) of the tank. Agitation When wettable powders (atrazine, etc.) are used, the return to
the tank should be 14–27 L/min for each 450 L of tank capacity,
depending on the concentration of the wettable powder and the size
of the tank. A dedicated line from the pressure side of the pump
(not the pressure regulator) to the tank must be used to carry the
liquid necessary for hydraulic agitation in the tank. Always use
a venturi jet or sparge tube. This flow can be reduced if the sprayer
has a mechanical agitator. Sparge tube agitation requires more water
than venturi nozzles Avoid excessive agitation of the mixture, as it may turn into an invert immulsion, a grease-like mass that will settle to the bottom of the tank and cannot be pumped. Excessive agitation may also cause foaming resulting in pumping problems. To prevent a build-up of oil in the sprayer, the tank should be emptied completely before refilling. After any break in the spraying operation, agitate thoroughly before resuming operation. Clean the tank and sprayer immediately after use with a detergent or solvent and flush with clean water. PumpsThe pump is the most important part of the sprayer. The pump should have adequate capacity to maintain the desired pressure, volume and agitation. Piston, diaphragm and centrifugal pumps are best for pumping wettable-powder suspensions. For liquid herbicide applications, roller pumps may be used in addition to the above types. When used for wettable powders or flowable formulations, choose a pump with an abrasion resistant housing. Carefully follow the manufacturer’s care and storage instructions for the best pump performance. CAUTION: Running a spray pump without water may cause damage or premature wear. Nozzle TipsNumerous companies make spray nozzles. Nozzles from different suppliers may be similar in design but may differ in setup requirements. Always follow manufacturers’ recommendations for nozzle spacing and nozzle-to-target distances. These distances may vary according to the spray angle of the nozzle. Proper spacing and orientation of nozzles is essential to ensure adequate overlap of adjacent nozzle spray plumes. Care should be taken to maintain a stable boom height to assure uniform overlap of the nozzle spray patterns. The success of the spray application is dependent in part on the
condition of the nozzle tips and the uniformity of application across
the whole spray boom. The spray pattern of all nozzles should be
examined prior to their use. In addition, each and every nozzle Materials used for nozzle tips range from brass, stainless steel,
hardened stainless steel, as well as plastics/ polymers and ceramics.
All product formulations and carriers cause wear of the nozzle orifice.
Wettable powders cause more wear than others formulations. Sprayers should be calibrated regularly (see note on Nozzle tips should be replaced when they deliver 10% more than
manufacturer’s rated output specifications. Worn nozzle tips
may provide uneven distribution of spray solution and cause undesirable
spray patterns. Flat fan nozzle tips are widely used on boom sprayers to apply
herbicides. Spraying operating pressure should be within limits
specified by the nozzle manufacturer. Nozzles with a 110 degree
spray angle have more overlap than 80 degree nozzles, resulting
in a wider spray angle. This allows less chance of spray skips as
the boom moves closer to the ground. Always follow manufacturer’s Flat fan nozzle tips that will operate at reduced pressure, approximately 140 kPa, are available. These nozzle tips can further reduce the potential of drift. Air induction or venturi nozzles are now available from at least
ten different suppliers. These nozzles were specifically designed
to reduce the amount of fine droplets produced in the smaller nozzle
sizes. The nozzle manufacturers offer air induction or venturi nozzles
in a wide range of sizes. These nozzles draw air into the nozzle as the spray liquid passes
through the nozzle. The result is a coarse spray with very few fine
spray droplets that are prone to drift. These coarse droplets contain
air bubbles that cause the droplets to rupture upon impact with
plant surfaces. Air induction nozzles are made for two pressure ranges, low pressure
and high pressure. If a sprayer cannot exceed 345 kPa, only consider
a low-pressure design. All venturi nozzles should be operated in
the middle of their working range. For the low pressure designs
this is approximately 275 kPa and in the high-pressure designs,
about 550 kPa. All venturi nozzle designs are extremely sensitive
to low working pressure. The spray patterns will collapse to less
than their designed spray angle if the nozzle pressure is too low.
This will result in a distorted spray pattern. In addition, the
induction of air into the spray liquid will not occur if the pressure Many producers have quickly adopted this new nozzle technology. The significant reduction in spray drift, compared to conventional flat fan nozzles, is a welcome feature. Some producers are using these nozzles for all their herbicide spraying. Some product performance problems have occurred when air induction
or venturi nozzles have been used. One or more of the following
factors may contribute to this. Poor timing of spray, reduced water
volumes, spray pressures that are too low and difficult-to-wet weeds
may all contribute to poor control. Special even-spray nozzles tips are available for band spraying
applications of herbicides. These even flat fan nozzles deliver
a uniform amount of spray over their sprayed area. A variety of
sizes, spray angles and nozzle materials are available. The nozzle-to-target
height, and spray angle of the nozzle tips as well as their orientation
to the direction of travel, determines the width of the sprayed
band. Carefully follow the manufacturer’s literature and directions. Flooding nozzle tips are used at low pressures and, because of
their wide spray angle, can be used closer to the ground surface,
thus reducing the potential for drift. New flooding nozzle tip designs
have improved the spray distribution patterns to the point that
it is as good as with the flat fan tips. Flooding nozzle tips are
available in brass, plastic/polymers and stainless steel. Half as
many of these nozzle tips are required to cover the same width as
would be required with flat fan nozzle tips. Sprayers equipped with
a broadcast type of nozzle cover a wide swath. They are especially
convenient for farm lane and fencerow spraying where a uniform spray
pattern is not essential. The spray pattern is affected by wind
and severe drifting may occur with even a light breeze. Never use
a broadcast-type of nozzle to spray near a susceptible crop. Full or hollow cone nozzle tips may be used for applying herbicides
to the soil surface when the herbicide is incorporated or mixed
into the soil with a disk harrow, cultivator or similar tillage
implement. NOTE: When using any nozzle for spraying wettable powders or micro-nutrients, it is essential to calibrate the sprayer frequently because, as a nozzle wears, the quantity of spray material delivered increases and distribution is uneven. Worn nozzles usually result in a poor spray pattern. Nozzle manufacturer’s catalogues will list screens required
for various nozzle types and sizes. Diaphragm check valve nozzle
bodies will ensure dripless operation when the boom is turned off.
To clean nozzle screens, remove them from the nozzle bodies and
wash
Cleaning the SprayerBefore cleaning the sprayer, dispose of surplus tank mix. As suggested
in the Grower Pesticide Safety Course, one method of disposal is
to dilute the remaining spray solution at least 10:1 with water.
This diluted solution can be applied to the previously treated area
as long as the maximum recommended product rate on the label, is
not exceeded. Clean out the sprayer immediately after finishing the day’s
work or when changing chemicals. At the end of each spray day, thoroughly
flush out the boom with plenty of water to rinse lines, diaphragm
check valves and nozzles. Delaying cleanout, even overnight, can
allow the formation of hard-to-remove deposits. The sprayer tank
is much more difficult to clean out, if it is allowed to dry. Don’t
forget to also clean out the measuring containers. Steps: 2. Drain spray tank. 3. Fill tank with water and add detergent, ammonia or other tank
cleaner product and agitate for 10–20 minutes (clean the whole
tank not just the bottom half). Flush boom and hoses with solution,
allow to stand for several hours (or overnight if possible) and
then flush boom and nozzles again and drain the tank. When flushing
the boom, open the boom ends to get particles out of the boom. 4. Inspect the inside of the tank for visual residues. Rinse the
inside of the tank if necessary. Repeat step 2. 5. Wash the outside of the sprayer with soap or mild detergent
and water. 6. Remove nozzles, screens, and wash separately in a bucket containing
cleaning solution. Wash out measuring containers with the cleaning
solution. 7. Remove all boom end plugs or caps. Product residues collected
in the ends of the various boom pipe sections could cause crop injury.
Thoroughly clean out the plugs or caps and pipe ends with cleaning
solution. Carefully replace all the boom end plugs or caps. Thoroughly rinse the tank, hoses, booms, nozzles and screens with
clean water for a minimum of 10 minutes. Repeat immediately before
the next use. Use household detergent at rate of 250 mL/100 L or 1 kg/150 L of
water. Use ammonia (3%) at 1 L/100 L of water. Use other cleaning
agents according to label directions. Never mix ammonia with chlorine
bleach. Chlorine gas is produced which may cause severe eye, nose,
throat, or lung irritation. NOTE: Contact the manufacturer of pesticides being used
to determine the best methods and product(s) to clean residue from
tanks and associated equipment. Read the label, since many products,
e.g. ACCENT, BANVEL II, CONQUEST, PEAK, etc. provide tank-cleaning
information on their label. Some products such as AGRAL 90, or ALL
CLEAR, are recommended as tank cleaning agents. Do not use equipment that has applied Group 4 (2,4-D, MCPA and
related phenoxy herbicides) or many of the Group 2 herbicides should
not be used to spray fungicides or other materials on susceptible
crops. Do not park or store such sprayers near greenhouses or other
areas where susceptible crops are grown. Clean the spray tank, booms and hoses first. Be sure to also clean
the nozzles and tips, screens, filter, strainer and pump. These
parts are often overlooked, and can trap residues. Because many
herbicides are highly active and concentrated, it is essential to
clean out every trace of herbicide. When surfactants or fertilizer solutions (e.g. AGRAL 90, 28% UAN)
are used in a recommended mix with herbicides, there may be some
inadvertent cleaning of previous residues from the tank or equipment
that could affect the crop. Proper cleanout when changing products
is essential to prevent crop injury. The wash water contains herbicide. Never allow wash water to run
into a well, lake, pond, river or other water source. Do not leave puddles that may be accessible to children, pets, farm animals or wildlife. Related Links
For more information: Toll Free: 1-877-424-1300 Local: (519) 826-4047 E-mail: ag.info.omafra@ontario.ca
|
||||||||
