Define the role before the features.
A portable sample test, an installed online measurement and a laboratory reference method serve different purposes. Begin with the decision the result needs to support, not the product name alone.
Sample
Where and when will it be collected?
Measurement
Which concentration and settlement results are required?
Records
How will completed results be compared?
Six questions for a useful specification.
Document the expected routine and its boundaries. This prevents a familiar headline term from hiding differences in sample handling, measurement method and operating responsibility.
What will be tested?
Identify mixed liquor or another sample type, the expected solids range and the conditions that must be investigated. Confirm that representative samples fall within the analyser’s specification.
Which results?
Separate concentration requirements such as MLSS from settlement results such as SVI, settled sludge level, supernatant clarity and floating sludge.
How will tests compare?
Define the sampling location, timing, preparation and whether the settlement method is stirred or unstirred. Agree what contextual information operators will record.
Check stated figures, not assumptions.
Compare the published range, accuracy, sample volume, test duration, storage, operating environment and communications against the site requirement. Ask the supplier to confirm anything not stated.
01 / Technical fit
Range and measurement method
For the S3A, the specified MLSS range is 50 to 6,500 mg/L with stated accuracy of ±10%. It uses a 210 ml sample, provides MLSS in approximately 10 seconds and completes settlement results after 30 minutes.
02 / Operational fit
Locations, records and routine
The S3A stores up to 28 completed results for each of three locations with date and time information. Confirm how those results will enter the treatment works’ wider records.
Ask what the instrument does not do.
The S3A is intended for safe-area operational wastewater-treatment checks. It is not a continuous online analyser and does not replace required final-effluent or laboratory compliance testing.
Optional MODBUS RTU over two-wire RS-485 supports read functions 03 and 04 and must be specified when ordering. Confirm required data with PMA; dashboards and network integration are client-provided. SSVI and stirred settled sludge level require the separate optional stirrer.
Connect the checklist to the evidence.
Use the broader category guide, portable MLSS analyser page, TSS vs MLSS guide and detailed S3A product information to verify each requirement before procurement.
View the reference
Review the portable S3A MLSS analyser for activated sludge: 210 ml sample, 50–6,500 mg/L range, rapid result, settlement data and limits.
Explore guideView the reference
Compare TSS and MLSS terminology, sample context and analyser roles, then see where the portable S3A fits activated-sludge operational checks.
Explore guideAnalyser types
Compare portable, online and laboratory measurement roles before choosing a product route.
Application guide
See how concentration and settlement measurements fit a repeatable process-monitoring routine.
S3A product
Review the published S3A measurement workflow, storage, power and operating information.