Choose one active basis
State whether commercial powder is treated as product as supplied or corrected by an active or solids fraction. Record product mass, make-down water and final solution volume. Use the same convention for all candidates.
Do not mix kilograms of product, litres of solution and pump percentages in one comparison without converting them.
Verify stock concentration
Measure feeder output and make-down water rather than relying only on setpoints. Account for tank heel, batch volume and continuous-system residence. Secondary dilution increases delivery volume but does not add active polymer.
Use solution density when the mass calculation requires it and document the assumption.
Calculate active polymer flow
Multiply solution mass flow by active mass fraction, keeping hours, minutes, kilograms and grams consistent. For batch operation, divide active product charged by the slurry dry solids treated during the same time window.
Retain enough digits during calculation to find unit errors, then round to feeder control resolution.
Calculate dry-solids flow
Multiply slurry volumetric flow by density and dry-solids mass fraction using compatible units. Match the solids sample to the recorded process interval.
A fixed solution pump setting delivers a higher dose when feed solids fall and a lower dose when they rise.
Express a usable ratio
Report active polymer mass per dry tonne or an equivalent clearly stated basis. Keep the product-as-supplied conversion available for purchasing and inventory.
Attach process endpoints to the dose: overflow clarity, settling, underflow, filtration, throughput or recycle quality.
Reconcile calculation with inventory
Run timed pump or feeder checks at several settings and compare calculated product use with bag counts, hopper loss or tank depletion. Investigate recirculation, calibration and concentration errors.
Approve an operating dose band, not one theoretical decimal. Set review triggers for feed solids and flow changes.
Work through a unit-controlled example
If slurry flow is recorded in cubic metres per hour, density in kilograms per cubic metre and dry solids as a mass fraction, their product gives dry-solids kilograms per hour. Polymer solution flow must be converted through solution density and active fraction to active kilograms per hour.
Dividing the two flows and multiplying by one thousand reports active kilograms per dry tonne. Keep a written unit line so a grams-versus-kilograms or percent-versus-fraction error is visible.
Handle continuous make-down systems
For continuous systems, measure powder feeder output and make-down water over a stable interval. Account for tank working volume, turnover and any recycle. A concentration setpoint is only credible when incoming mass and outgoing solution agree.
Short-circuiting can deliver young dilute solution even when the average calculation appears correct. Compare residence and application response at peak draw.
Handle batch systems
Record powder mass, actual fill volume, batch start, maturation release and volume remaining before the next batch. Prevent fresh solution from being used before the approved aging time.
Allocate product only to the process dry solids treated during the same batch-use interval. Tank level estimates should be checked against a calibrated scale or timed transfer where accuracy matters.
Calculate dose uncertainty
Flow meters, solids tests, feeder checks and solution concentration each carry uncertainty. Use duplicate measurements and realistic significant figures. A calculated 0.001-unit difference is not actionable when feed solids vary several percent.
Define a normal operating band and the measurement change required before adjusting dose. This prevents constant pump movement in response to noise.
Compare commercial products fairly
Convert every candidate to the same active or stated product basis and attach the same separation endpoints. Include delivered price, package loss and preparation yield when calculating treatment cost.
A product requiring fewer kilograms may not be better if it narrows the stable window, reduces underflow density or increases recycle solids. The final comparison belongs to the whole process record.
Link dose control to changing feed
Where online solids or reliable density-flow measurements exist, calculate a feed-forward target within the approved dose band. Apply limits and filtering so one noisy value cannot drive a large chemical step. Confirm the calculated output against actual feeder or pump capacity.
Where instruments are unavailable, use a documented manual update interval based on representative solids and flow measurements rather than leaving one pump percentage for every condition.
Audit the mass balance routinely
Choose a practical interval and compare theoretical product consumption with bags used, hopper weight or batch depletion. Record spills, purge, off-specification solution and maintenance losses instead of forcing the inventory to match the calculation.
A persistent difference indicates an error in feeder calibration, solution concentration, flow, solids or record timing. Correct the measurement before optimizing chemistry around an inaccurate dose.