Pumps, valves, probes, fittings, tubing and sensing components for precise sample preparation, reagent handling and instrument fluidics.
Valveless Metering Pumps for Repeated Reagent Dispensing
Application guide · Repeated dispensing
Repeated reagent dispensing with a valveless rotary-piston pump is defined by volume per event, event rate and the receiver. Select displacement and speed so the target dose is delivered in a controlled portion of a revolution while leaving time for liquid release, valve phasing and any cleaning action.
Engineering example: a 100 μL dose from a 100 μL/rev setting corresponds to one theoretical revolution. A 20 μL dose at the same setting corresponds to 0.2 revolution, but this arithmetic does not prove 20 μL delivery; start/stop phase, slip, nozzle retention and motor control must be tested.[1][2]
01Define the liquid, receiver and complete duty before selecting the component
Translate the analytical task into an engineering duty
Use case
Inputs to define
Decision supported
Reaction reagent
Dose, additions per minute and allowed timing jitter
Match displacement and speed to the event
Buffer or wash additive
Larger repeated volume and line length
Include prime and outlet emptying
Crystallizing reagent
Solubility, idle time and cleaning liquid
Provide piston-area wash or scheduled replacement
02Calculate the working point and the margin the instrument really needs
Calculations to complete before prototype selection
Quantity
How to define it
Why it matters
Theoretical revolutions
target dose ÷ selected μL/rev
Use only as initial motion planning
Event time
revolutions ÷ rpm + acceleration and dwell
Compare against instrument cycle
Daily consumption
accepted dose × tests + prime and wash
Sizes source and waste reservoirs
Use minimum, routine and maximum conditions rather than one nominal point. Include the first cycle after priming or idle, the lowest source level, the highest expected restriction and the actual receiving geometry. A nominal capacity, free-flow value or theoretical command increment is not an acceptance result.
03Map the task to a FOREACH configuration and the rest of the fluid path
04Program the full liquid cycle, including prime, wash and recovery
Prime until bubble-free→Align inlet phase→Fill displacement chamber→Rotate to outlet phase→Deliver and allow release→Wash before idle if required
A complete method cycle is more than the active delivery step
The exact physical order and parallel actions depend on the instrument. Retain each state in the control and verification plan.
Record valve states, motion, dwell, sensor windows and rejected recovery cycles. This makes throughput and liquid consumption auditable and prevents a fast component movement from being reported as the complete analyzer cycle.
05Design abnormal-state diagnosis before the fault occurs
Observed result, likely mechanism and useful next action
Observed condition
Likely mechanism
Engineering response
Dose decreases with pressure
Slip or outlet restriction
Measure installed pressure and select another work point
First dose after idle differs
Drainback, evaporation or crystallization
Define prime/recovery routine
Nozzle retains droplets
Surface tension or dispense geometry
Change tip, speed or contact dispense method
The controller should distinguish a recoverable event from a result-invalidating event. A retry is useful only after the original cause has been removed and the liquid path has returned to a verified state.
06Accept performance where the liquid is actually used
Minimum qualification plan for the integrated channel
Result
Where or how to measure
Acceptance question
Dose
Collect at final nozzle
Minimum/routine/maximum dose
Sequence
First, steady and last dose
No unacceptable trend
Recovery
After idle, empty source and cleaning
Defined number of rejected or recovery cycles
Test the exact liquid and complete wetted path at minimum, routine and maximum conditions.
Separate first-cycle, steady-state and post-idle results; do not average away recovery behavior.
Challenge the relevant fault and confirm the controller prevents an invalid result from being accepted.
Retain the configuration, software sequence, consumables and receiving-position result together as the qualification record.
