POWDER ADSORBENTS · PURCHASING SPECIFICATIONS
Powder Adsorbent Particle Size Reports: D50, D90 and Purchase Limits
“Fine powder” is not enough to compare two quotations. Before approving activated molecular sieve powder or powdered activated carbon, connect the reported size to its measurement basis, method and intended formulation or process.
Read the Metric Before Comparing the Number
Dv50
The median of a volume-based distribution: half of the measured particle volume falls below this diameter. It is not the largest particle.
Dv90
The diameter below which 90% of the measured particle volume lies. It describes the coarse side of the distribution, not a guarantee that every particle is smaller.
“Average size”
Ask which statistic and distribution basis are meant. A median, a mean and a number-based result are not interchangeable labels.
HORIBA’s particle-size specification note explains why a single midpoint cannot describe distribution width and why the measurement basis matters. Keep the supplier’s exact notation and units in your comparison sheet.
Five Details to Request with the Result
- Identity: product grade, sample or batch reference, and the document revision.
- Result definition: the exact metric, distribution basis, units and whether the figure is a typical value or an agreed release limit.
- Measurement method: technique, applicable procedure and instrument/report identification.
- Sample preparation: wet or dry dispersion and the documented preparation conditions used by the laboratory.
- Distribution evidence: the curve or additional reported percentiles relevant to the buyer’s concern, rather than a bare “average” number.
For example, a request that says only “D50 meets our limit” leaves the coarse fraction and test basis unresolved. If coarse particles are the concern, ask the technical reviewer which additional criterion and method should be included. Do not invent a maximum-size limit from D50 or D90.
Why Two Reports Can Disagree
Different preparation conditions can change the dispersed state being measured. Malvern Panalytical’s dry-powder method guidance identifies representative sampling, dispersion and measurement conditions as central to reproducibility. It also distinguishes breaking up agglomerates from damaging particles during dispersion.
For procurement, request clarification of the two methods before treating a difference as a material defect or a supplier improvement. Keep the original reports, have the responsible laboratory agree a comparable basis, and record whether a repeat comparison is needed. This guide does not prescribe a dispersion pressure or preparation recipe for an unknown powder.
Connect the Report to the Actual Product Trial
Formulation powder
Use the size report alongside the controlled resin-system trial. Record dispersion, appearance and processing acceptance in the molecular sieve powder trial guide.
Powdered carbon
Keep the particle-size comparison attached to the liquid-treatment trial and separation requirements. Use the PAC decolorization trial guide.
Bulk release
Carry the approved grade, method and agreed limits into the purchasing record. Preserve a route for reviewing a changed product or test method.
A matching size result does not by itself approve adsorption performance, formulation compatibility or filtration behavior. Define those acceptance decisions separately.
Copyable Particle-Size Specification Request
Product and intended use:
Existing grade or reference sample:
Particle-size concern and trial observation:
Required metric and distribution basis:
Units and proposed acceptance limit or range:
Measurement procedure and revision:
Sample preparation and dispersion conditions:
Sample/batch identification and report:
Typical data versus lot-release requirements:
Technical reviewer and change-approval process:
Leave an undecided limit open for technical agreement rather than copying a number from another powder. Once agreed, use the same wording for sample review, quotation comparison and the order specification.
Request Powder on a Comparable Specification
Send the application, existing grade, particle-size report, trial requirements, quantity and destination. Specify whether you need loose activated molecular sieve powder or powdered activated carbon so the enquiry starts with the correct product form.
Send Powder Requirements