Automated analysis and in vitro diagnostics: reagent dispensing
In automated analyzers and in vitro diagnostics (IVD) reagent circuits, liquid travels from a reagent bottle through the pump, tubing and dispensing tip into a reaction vessel. The component may be specified as a reagent dispensing pump or reagent dosing pump. Define the volume required by each analytical step and the time available to deliver it, not only the flow per minute.
Displacement and complete operating revolutions determine nominal dose volume. Calculation example: 80 μL/rev × 5 revolutions = 400 μL. At a constant 150 rpm, those revolutions take 2 seconds, excluding acceleration, stopping and other machine actions. This is a sizing calculation, not measured performance. Recalibrate output after changing the displacement setting.
Commission the circuit by priming and removing air, fixing displacement and cycle count, collecting repeated doses, and correcting output. Compare continuous dispensing with the first dose after a pause. A first-dose deviation calls for inspection of bubbles, tip droplets and liquid retraction. Supplying reagent from a reservoir is not equivalent to aspirating and transferring a sample.
Automatic titration: incremental titrant dosing
In laboratory titrators, a titrant dosing pump delivers liquid to the titration vessel under instrument control. The sequence combines an addition, mixing and electrode response, followed by the decision on the next addition. The pump supplies liquid; the instrument detects and determines the endpoint.
Specify initial delivery speed and the smallest reliable increment near the endpoint separately. At unchanged displacement and complete revolution count, reducing speed mainly increases delivery time, not dose volume. 12 μL/rev is the lower end of the displacement range, not a validated minimum titration increment. Do not infer arbitrary small doses by dividing it by motor steps.
Collect and measure repeated target increments with the actual titrant, tip and tubing. Check droplet carryover after stopping and leave time for mixing and stable readings. Drive positioning and start/stop behavior must support the required sequence; the pump accuracy specification alone is not the analytical accuracy of the complete titrator.
Reagent production and laboratory dispensing: small-container filling
At a small-vial or reagent-tube station, RPL-P4 can be assessed as a reagent filling pump or volumetric dispensing pump. After the dispensing tip delivers liquid, the instrument indexes the next container. Assess the volume actually received by each container during continuous operation and after pauses.
Break cycle time into pump delivery, container indexing, tip motion and settling. In the 400 μL example at 80 μL/rev and 150 rpm, 2 seconds is only the theoretical pump running time; it does not demonstrate 30 bottles per minute. If the cycle is too long, assess displacement, drive speed and station motion together.
Measure initial fills, consecutive fills and the first fill after a pause separately. For gravimetric checks, convert mass to volume using liquid density at the test temperature and an appropriate balance. With foaming or wall-wetting liquids, also inspect tip retention and whether the entire droplet enters the container.
Define the fluidic task and configuration
Provide liquid composition, dose volume or continuous flow, allowable delivery time, daily run duration, inlet conditions, outlet backpressure and drive requirements. Use these inputs to size displacement and timing, then verify output in the actual circuit. Application directions are not claims of validation in every listed instrument.
