When engineers select a Dosatron model, the first number they look at is the flow rate range. This makes sense — the Dosatron must be able to handle the volume of water flowing through the system. But the second selection — the dosage range — is where most specification errors happen, and the consequences of getting it wrong are more severe than getting the flow rate wrong.
An incorrect dosage range produces a system that either cannot dose at the required concentration or cannot dose accurately within the required range. Neither problem is immediately obvious at commissioning. Both become apparent when the application fails to perform — crops that show nutrient deficiency, animals that do not respond to medication, processes where the chemical treatment is inconsistent.
What the dosage range means
Every Dosatron model is specified with a dosage range expressed as a percentage — for example, 0.03% to 0.3%, or 0.2% to 2%, or 1% to 10%. This range describes the minimum and maximum concentration of chemical that the device can inject into the water stream at the adjustable setting.
A dosage of 0.2% means 2 ml of chemical concentrate per litre of water passing through the device. A dosage of 2% means 20 ml per litre. The Dosatron’s dosing body is mechanically adjustable within its rated range, which allows the operator to set the exact injection ratio needed for the application.
The critical point is that the dosage range is a fixed mechanical characteristic of each model. A Dosatron specified with a 0.03% to 0.3% range cannot dose at 1% concentration, regardless of how the adjustment dial is set. A model specified at 0.2% to 2% cannot reliably dose at 0.05% — at the extreme low end of the adjustment, the dosing mechanism loses accuracy. Selecting the wrong range creates a device that is fundamentally mismatched to the application’s requirements.
How to determine the correct dosage range
The calculation starts with two numbers: the concentration of the chemical in the product container (the concentrate), and the concentration required in the water delivered to the crop, animal, or process (the target solution).
The required dosage percentage is: (target solution concentration ÷ concentrate concentration) × 100.
As a worked example: a fertiliser concentrate contains 20% nitrogen equivalent. The target nutrient solution delivered to the crop is 0.1% nitrogen. The required dosage is (0.1 ÷ 20) × 100 = 0.5%. The Dosatron must be able to dose at 0.5% — which means the model’s dosage range must include 0.5% within its adjustable window, and ideally with room on both sides to allow for minor formulation changes or seasonal adjustments.
A Dosatron with a 0.2% to 2% range covers this requirement comfortably. A model with a 0.03% to 0.3% range does not — 0.5% is above its maximum. A model with a 1% to 10% range includes 0.5% below its minimum, where accuracy will be poor.
Why operating at range extremes causes dosing error
The Dosatron dosing piston is calibrated to deliver accurate injection across its rated range. At the extreme low end of adjustment — the minimum percentage setting — the dosing piston travel per motor cycle is very small. Minor mechanical variation, seal wear, or fluid viscosity begins to have a proportionally larger effect on the actual volume delivered. The accuracy at the bottom of the range is lower than at mid-range settings.
At the extreme high end — maximum percentage setting — the piston is travelling at its maximum displacement per stroke. There is no further adjustment headroom. If the application requires a slightly higher concentration than expected, there is no room to compensate without changing the model.
The practical guidance is to select a Dosatron model where the required application dosage falls in the middle third of the device’s rated range. This provides the best accuracy and leaves adjustment headroom in both directions for operational flexibility.
Common misspecification patterns
The most common error is selecting a model based on flow rate alone and accepting whatever dosage range happens to come with that flow model. Flow rate and dosage range are independent specifications in the Dosatron range — a given flow capacity is available in multiple dosage configurations. Selecting by flow rate without checking dosage range is selecting only half the specification.
A second common error is calculating the required dosage based on the nominal concentrate concentration stated on the product label, without accounting for formulation variability. Chemical concentrates from different batches or suppliers may have slightly different active ingredient concentrations. If the specification is calculated to the exact minimum of the dosage range, a batch with lower active ingredient concentration cannot be corrected by adjusting the Dosatron upward.
A third error occurs when the application requires multiple chemicals at different dosage ratios, and a single Dosatron model is specified to handle all of them. Each chemical’s required dosage percentage must be checked independently against the model’s dosage range. A model that correctly doses fertiliser at 0.5% may be completely wrong for a biocide requiring 0.05% or a pH modifier requiring 2%.
The consequence of selecting a range that is too high
If the dosage range is set too high relative to the required application concentration, the Dosatron will deliver more chemical than needed even at its minimum setting. The operator has no way to reduce the dosage further. The options are to dilute the concentrate before filling the chemical tank — which introduces manual preparation variability — or to replace the model with one that has the correct range.
In a livestock medication application, a Dosatron with too high a dosage range delivering medication above the therapeutic threshold is not just an accuracy problem. It is a welfare and potentially a regulatory issue. The dosage range must match the required concentration window, not merely be close to it.
The correct specification approach
Calculate the required dosage percentage for the application. Confirm that this percentage falls within the middle third of the selected Dosatron model’s rated range. Verify that the same model’s flow rate range covers the actual system flow rate. Check whether the dosage calculation allows for adjustments in both directions to accommodate concentrate variability or seasonal changes in the application requirement.
If the flow rate and dosage range requirements point to different models, the dosage range takes priority — because a wrong dosage range cannot be corrected in the field, while a slightly oversized flow capacity can be managed through installation design.
Autoflo Technology is the official distributor of Dosatron dosing injectors in Malaysia. For help calculating the correct model and dosage range for your specific application, contact us at info@autoflotechnology.com.