Injection Systems – Agricultural Spraying, Applying Chemicals and Fertilzers

Injection Systems offer new safe ways to avoid mixing, loading mishaps and messes when spraying applying fertilizers and chemicals.

injection systems for spraying fertilizer and chemicals the way of the future

Did anyone tell you that in the very near future, regulations are going to control the way we mix pesticides and load sprayers in ways we haven’t imagined! And we are not going to be able to carry mixed loads down the road to the field or between the fields we are spraying!!

The result of all this eventually, will be that we are going have to inject the pesticide into the pressurized spray line somewhere between the pump and the nozzles.

GREAT! No More Agitation Headaches!

The up-side of all this is that the injectors will carry the materials right out of their original containers into the flow and out onto the crop. Mixed liquid will not recirculate into the tank and therefore the tanks will be clean. Relief valves in the main pump will carry only water back into the tanks, the excess that is by-passed by the pressure control units.

“Mixing and loading” will be limited to water treatment, such as adding surfactants, pH buffers and stickers. (on second thought, some of these are messy, and so some residue will stay in the tanks, but none of it is really toxic.)

The spray equipment will have to be modified to include areas where the containers of concentrated chemicals can be placed to feed the injectors. Sprayers will have to have banks of two or more injectors to allow the injection of two or more chemicals that are normally used in combination with each other in current tank mixes.

Applying soup mixes (combinations of insecticides, fungicides, nutritionals) will become impractical and too costly. (This, in my opinion, is a blessing, because many of those soup mixes combined chemicals that actually “cancel” each other out; but who is going to convince the grower of this, when he maintains that it has worked for him for years).

The chemical suppliers will be reformulating and packaging their materials in user-friendly containers and there will be a proliferation of injection systems on the market, as well as the usual complement of “gimmicks” designed to make the operation more effective, safer and economical. Wettable powder and soluble granule formulations will have to be converted to flowable combinations that can be handled by the injectors.

And high pressure sprayers will have to add a booster pump to elevate the pressure to working levels after the injection stage, because the cost of a high pressure injection system would be prohibitive and impractical.

One of the basic concepts in injecting chemicals into a stream (in this case the spray hose), is to keep the proportion of the injected material as close to the specification as possible. Consequently, because the flow of spray will not be constant due to nozzle controls, pressure variations and other operator changes during the spraying process, the injector should be a proportioner that will adjust to the variations in the flow.

There are different types of injectors on the market, but only those that are driven by the actual flow in the line will proportion as well as inject and react to changes in the flow rates.

In other words, electric and vacuum (venturi) injectors will not assure the accuracy of the mix of spray chemicals if the flow rates and pressures in the spray lines are not constant.

dosatron flow driven injectors work well for low pressure non electric injector applications

Flow-driven injectors such as the Dosatron and Dosmatic are ideal for this type of installation because they are non- electric (powered by the actual flow of the line they are injecting into), simple, accurate, chemical resistant and easy to maintain and service.

However, these proportioners were designed for low pressure systems as they basically were meant to be used in irrigation systems, which rarely operate over the 100psi pressure level, and more likely run at about 60 to 70 psi.

The Dosatrons and Dosmatics are very accurate and easy to calibrate, generally from 0.2% up to 2.5% and in volumes from practically ounces per minute up to 100 gpm, and, being non-electric (water driven) they are virtually trouble- free.

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As a matter of fact, these units can be set up in tandem to proportion 4 or 5 chemicals into the same flow and mix them in the order that the manufacturers recommend, for a well-balanced final spray solution.

This system will work very well with the large boom sprayers and herbicide applicators that operate at pressures under 100 psi and can be just “plugged” into the spray lines beyond the pumps and relief systems. A back-flow prevention device will have to be placed in the line between the pump and the injectors so that the mixed solution does not have a chance of being flushed back into the tank and fill systems.

When the sprayer operates above 100 psi, a booster pump will have to be added after the injection station to take the pressure up to the required level for the nozzles. This would be on boom sprayers operating above 100 psi, air-blast sprayers and mist sprayers that require high pressures to generate fogs or other small droplet patterns.

These pumps would be the current pumps on the machines, such as piston, plunger or diaphragm units and would have to be re-plumbed to kick-in after the injection process.

There will be a host of other injection systems and proportioner pumps being made available either for retro- fitting or as original equipment on new sprayers. Some of these pumps generate high pressures and thus can be installed after the main pressure pump on high pressure units.

However, even though they are very accurate in the flow that they deliver and can be calibrated to exacting specifications, the proportion of the material that they are injecting into the spray line can change with the normal changes in pressure and flow caused by variations of the pumps, pressure relief valves and shutoffs, especially in on-off cycling applications such as Smart Sprayers, Tree-Sense, Tree-See and other specialty applicators controlled either by computer or operator.

A possible solution to this type of situation is to have the injectors feeding into a holding tank from where the mixed solution is then pressure pumped to the nozzles. This tank would act as a compensation chamber and the proportion of mix solution in it would be always constant to what has been set by the operator.

The Relief Loop

Another consideration in the use of pressure pumps after the injection point is that their relief system will have to loop back into the pumps own inlet valves, very much the same way that pressure washers are plumbed, because the excess coming out of the relief valve is a mixed solution and cannot go back into the fresh water tank. This may also require another backflow preventer to protect the injector pumps and keep the pressure down in the holding tank.


It may take some time for legislation to mandate these changes to the way we are running our spray machines. If you operate at pressures below 100 psi, you will not be facing major changes. If, however, your machines are high pressure units, you will be looking at some important modifications and alterations to your present equipment.

You might want to look at the use of drift control nozzles and lower pressures and do some testing of your own to see if you can get the coverage and results on your crop that until now, you thought you could only achieve with high pressure fogging or atomization.

Meanwhile, the first indication of these sweeping changes will be the wider use of pre-packaged chemicals: soluble packs and pre-measured containers. The market will see manufacturers offering “quick-fill” systems and special collar systems that practically eliminate spillage and even contact with the materials. And you will be urged to mix what is necessary to treat the specific field and not transport it out on the roads to other locations.

But, unless something earth-shattering happens to our system of government, the implementation of the rules is still a ways down the road, if WPS is any example.


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