Pumps, valves, probes, fittings, tubing and sensing components for precise sample preparation, reagent handling and instrument fluidics.
Filters and Check Valves for Analyzer Fluid-Path Protection
Application guide · Fluid-path protection
Filters and check valves protect pumps, valves, probes and detectors from particles, reverse flow and siphoning. They also add resistance, cracking pressure and internal volume, so protection must be placed where it prevents the defined fault without hiding another one.
Engineering example: a clean filter that contributes 20 kPa at the target flow may rise substantially as particles accumulate. If the pump has only 10 kPa remaining pressure margin, the channel can fail before the planned replacement interval; a pressure trend or larger filter area is needed.[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
Particle protection
Particle source, allowable size and loading
Place upstream of the vulnerable component
Backflow prevention
Reverse head, siphon and acceptable cracking pressure
Protect source identity without blocking low-flow operation
Gas/liquid protection
Foam, condensate or full waste vessel
Use separator/trap and level control before gas path
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
Clean pressure drop
flow, viscosity and filter area
Reserve operating margin
Loading capacity
particle mass/events before service
Sets replacement interval
Cracking pressure
available forward differential
Must open at minimum operating condition
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
Establish clean baseline→Monitor pressure/flow→Challenge defined fault→Alarm before result failure→Replace without contaminating path→Prime and verify after service
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
Flow gradually decreases
Filter loading
Trend differential pressure and replace
Intermittent backflow
Check valve contamination or low reverse head
Inspect orientation and seal condition
Protection causes dose error
Added compliance, volume or cracking pressure
Reposition or select lower-impact component
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
Protection challenge
Defined particle/backflow/overflow case
Protected component remains safe
Normal operation
Minimum flow/dose and worst viscosity
Protection does not prevent valid cycle
Maintenance
End-of-life and replacement process
Alarm and recovery occur before analytical failure
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.
