Pumps, valves, probes, fittings, tubing and sensing components for precise sample preparation, reagent handling and instrument fluidics.
Diaphragm Pumps for Water and Working-Liquid Replenishment
Application guide · Replenishment
Replenishment keeps a day tank or local reservoir inside an operating window while downstream metering continues. Define the consumption peak, low/high level thresholds, recovery volume and recovery time before selecting the transfer pump.
Engineering example: restoring 300 mL between low and high levels within 60 seconds requires 300 mL/min installed flow. If the analyzer consumes 60 mL during that minute, the pump must supply about 360 mL/min at the installed load to achieve net recovery.[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
Purified water day tank
Peak use, tank working volume and hygiene interval
Prevent stagnation and overflow
Wash-solution reservoir
Composition, replacement frequency and foam
Match wetted materials and inlet condition
Working liquid replenishment
Method concentration and mixing requirement
Do not dilute a prepared solution unintentionally
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
Net recovery flow
restore volume ÷ time + simultaneous consumption
Use as installed flow target
Level hysteresis
high threshold − low threshold
Prevents rapid cycling
Run duty
recovery time × events per day
Select motor and service-life target
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
Detect low level→Confirm source available→Start transfer→Reach high threshold→Stop and isolate→Diagnose timeout or overflow
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
Frequent short cycling
Narrow hysteresis or sensor noise
Increase valid level window or debounce
Tank does not recover
Source empty, filter loaded or line restricted
Use timeout plus pressure/flow diagnosis
Level rises after stop
Siphon or valve leakage
Add and verify directional isolation
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
Net recovery time
Worst simultaneous consumption
Returns from low to high within target
Level control
Multiple cycles and sensor tolerances
No overflow or chatter
Fail-safe
Empty source, stuck sensor and power loss
Defined safe stop and alarm
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.
