Locate the task in the fluid path first
Arrows indicate task relationships, not that every component is connected in series in one tube. Check valve positions, pump wetted boundaries and operating states for each branch.
Determine whether the method measures dissolved, particle-associated or other specified constituents before deciding on filtration. Combine sample volume, reagent order, mixing and measurement windows into a complete cycle, including bottle-change priming and first-dose recovery.
Common product roles and application guides
| Product category | Role in this instrument |
|---|---|
| Piston pump | Sample and reagent metering inside analytical units |
| Syringe pump | Aspiration, dispensing and ratio preparation in suitable configurations |
| Diaphragm pump | In-cabinet washing and auxiliary-liquid supply |
| Multiport rotary valve | Sample, reagent, wash-liquid and bypass selection |
| Bubble and pressure detection | Signals for investigating delivery anomalies inside the cabinet |
| Tubing connections and protection | Method-permitted water-sample filtration or component protection; internal wetted and reaction-path connections |
Operating requirements differ by step
| Stage | Task category | Operating conditions to define |
|---|---|---|
| Sample metering: define permitted pretreatment | Sampling conditions | Actual sample volume, remaining source volume, probe-tip height, aspiration/dispensing speed and system liquid |
| Reaction reagents: complete the cycle in the method's specified order | Delivery and reaction timing | Working volume, addition order, liquid-arrival delay, mixing wait and detection trigger |
| Filter protection: check analytes and components separately | Protection and method conditions | Target components, pore size/material, filtration area, pressure drop, check-valve cracking pressure and leakage |
Sample metering: define permitted pretreatment
Include particles, salinity and matrix variation in the water-sample requirements. Validate metering at the analytical unit's receiver, separately from field-sample refresh time.
Reaction reagents: complete the cycle in the method's specified order
Adding the same volume at different times can change a reaction. Record each actual delivery, mixing, temperature control and measurement time, then assess the reaction result.
Filter protection: check analytes and components separately
Filtration can reduce particle entry into components while also changing the measured sample. Assess adsorption, retention, pressure drop and recovery after replacement. Method acceptability takes priority over mechanical protection.
Explore configurations through product application guides
Validate the complete cycle through application results
Assess dose, reaction, blanks and recovery according to the method, and verify what is measured after filtration.
| Step to validate | Measurements or observations | Priority troubleshooting checks |
|---|---|---|
| Sample metering: define permitted pretreatment | Measure actual delivery at the receiver, covering routine small volumes and maximum task volume, first dose after idle, sample changes and high/low concentration sequences | Air aspiration, clots/particles, probe contact with a wall or leakage alter actual delivery |
| Reaction reagents: complete the cycle in the method's specified order | Measure volume, actual arrival time and complete-reaction results together | Mismatch between liquid arrival and control trigger, residual droplets or inadequate mixing may alter reaction initiation |
| Filter protection: check analytes and components separately | Evaluate targets before and after filtration, blanks, recovery or method-specified metrics. Check increasing pressure drop, backflow protection and recovery after replacement. | Clogging, adsorption, leaks or excessive cracking pressure can alter delivery or method results |
Validate field representativeness and internal metering separately. Filtration intended to protect components must still meet method requirements.
Common selection and recovery questions
What should be confirmed before adding a filter to protect pumps and valves?
First establish the target fraction and whether the method permits the treatment, then check analyte loss, pressure drop, blanks and recovery after replacement. Unrestricted flow alone does not establish sample validity.
How do analyzer metering and field sampling relate?
This guide checks delivery and reactions after the sample enters the analyzer. For sampling locations, transfer renewal and field maintenance, see environmental monitoring. Record acceptance separately for each stage.