What do these products do in this instrument?
Piston pumps: metered sample and reagent delivery
Located at the metering-drive end of sample or reagent probes, they deliver specified volumes to reaction cuvettes. First establish whether sample remains at the probe tip under system-liquid drive or enters the pump head, then coordinate aspiration, dispensing, probe movement and replenishment.
EA, SM and TM provide options for comparing capacity, wetted configurations and installation space. Verify actual doses from working stroke and the complete wetted path; check system-liquid drive and direct sample contact with the pump head separately.
Distinguish piston displacement from actual received volume
Piston pumps use controlled displacement for discrete aspiration and dispensing. Sample may enter the head directly or remain at the probe tip while system liquid transmits displacement; wetted coverage, priming and cleaning differ. Map aspiration, holding, dispensing and replenishment paths first, then relate stroke to probe-tip delivery.
Further technical reading
Combine metering, valve positions and container actions into a complete cycle
Delivery requires coordination of metering drive, source switching and receiving-end actions. Usable capacity must cover working volume and other cycle displacements, with replenishment in permitted windows. Check tip droplets, bubbles and shared residual liquid through the complete path; remeasure received volume after changing pump heads, tubing lengths or interfaces.
Translate actual branch conditions into configuration requirements
| Condition | To confirm |
|---|---|
| Working stroke | Budget sample and reagent doses separately, including any system-liquid, priming and refill displacement required by each probe cycle. |
| Liquid contact and pressure | Identify which parts contact sample, reagent or system liquid, and specify the pressure and receiving cuvette for each valve state. |
| Delivery and recovery | Measure cuvette receipt after low-source-volume aspiration, idle periods, bottle changes and washing; assess carryover separately from volume error. |
| Operation | Specific operating conditions |
|---|---|
| Sample aspiration and transfer | Method-permitted sample type, actual dose, remaining source volume, probe position, aspiration/dispensing program and direct-contact or system-liquid architecture |
| Metered reagent dispensing | Actual reagent formulation, dose, doses per fill, refill and bottle-change windows, backpressure and reaction-cuvette position |
Compare product configurations by the roles on this page
| Product | Configuration option | Conditions to verify |
|---|---|---|
| EA standard piston pump | Finite-stroke metering | Compare configurations by routine dose, total cycle displacement and wetted materials |
| SM miniature piston pump | Discrete metering in compact installations | Check installation space first, then validate working doses and actual accuracy |
| TM ultra-miniature piston pump | Discrete metering in limited space | Check installation space and configuration before measuring actual delivery; an ultra-miniature design does not imply a smaller reliable dose |
Explore specific operating and validation tasks
Sample aspiration and transfer
Low remaining volume, probe contact with a wall and aspiration/dispensing reversals may alter delivery. First measure error in the target container, then assess residue using a blank after a concentrated sample; one calibration cannot address both issues.
Metered reagent dispensing
For repeated dispensing, record usable doses per fill and replenishment points. Confirm restoration of the liquid column after replenishment before evaluating the first dose. Retrying an interrupted action must also avoid duplicate addition to the same cuvette.
Confirm product roles in actual operation
| Operation | Measurements and observations | Priority checks |
|---|---|---|
| Sample aspiration and transfer | Measure received sample volume over the working range and after idle. Assess the sample-change sequence with high/low concentrations and washing, separately from volume calibration. | Air aspiration, sample particles or clots, probe-wall contact, leakage and shared-path residue can change delivery or the next sample; distinguish volume error from carryover. |
| Metered reagent dispensing | Measure first, middle and last reagent doses and the first dose after refilling or bottle changes. Confirm actual cuvette receipt and timing before retrying an interrupted addition. | An empty source, bubbles, probe droplets or a changed load can affect a dose; repeating a partly completed command can also add reagent twice to the same cuvette. |
Evaluate sample delivery, reagent delivery and carryover at the reaction cuvette. A correct pump displacement does not establish the received volume or recovery after washing.
Are piston pumps of equal capacity directly interchangeable?
Also check wetted materials, interfaces, mounting, drive and pressure conditions. After replacement, recheck delivery, cleaning and first-dose recovery with the original sequence and actual liquids. Capacity is only one comparison criterion.
The assay determines sample suitability; full-scale metering specifications cannot replace small-dose and complete-instrument results.