A PAC purchase specification needs more than a color description or one percentage. Read basicity, aluminum reporting basis, supplied form and the relevant quality documents together. A material that looks familiar is not automatically chemically equivalent, approved for the intended use or suitable for the existing feed system.
Put each specification in its own column
Basicity and aluminum concentration are different attributes. Basicity describes the extent of pre-neutralization of the aluminum coagulant; it is not another name for purity. An aluminum value may be expressed as Al or as an Al2O3 equivalent. The reporting basis, method and whether the value applies to the delivered product must be stated.
USALCO's DelPAC 2020 resource page provides an example of a manufacturer publishing separate product and technical information for a named coagulant. Its product-specific claims and approvals are not transferable to an ENVO supply. The useful purchasing lesson is to obtain the current documents for the exact product being compared.
| Specification item | What to request | What it cannot establish alone |
|---|---|---|
| Al or Al2O3 reporting basis | Declared basis, supplied form and test method | Equivalent performance at an equal delivered volume |
| Basicity | The defined calculation or method and grade range | Universal performance or an impurity limit |
| Appearance and insoluble material | Grade description and agreed acceptance tests | Purity inferred from a photograph |
| Use-specific quality requirements | Current, applicable documents for the named grade | Approval of every product from the same supplier |
Keep form and reporting basis attached to the result
A powder specification and a delivered-liquid specification should not be compared by stripping away their headings. Likewise, a laboratory result on a prepared solution does not automatically describe the original shipment. Ask which sample was tested, how it was prepared and which product identifier appears on the report.
For liquid products, density may matter when a plant converts volumetric delivery to chemical mass. For powders, the preparation instructions and actual dissolution arrangement matter. Keep these handling questions separate from the certificate comparison. A technically comparable composition still requires a feed-system and application review.
Use color as an observation, not a purity test
Appearance can be recorded during receiving inspection, but lighting, container depth, form and photography affect what a buyer sees. A photograph cannot replace the agreed analysis. If the appearance changes, identify the lot and ask for a documented explanation before accepting or rejecting it on visual grounds.
Prepare an acceptance list before ordering. State the essential indicators, units, reporting basis, analytical methods where required, sampling arrangements and documents needed for the destination. Define how a nonconforming or ambiguous result will be investigated. This turns a disagreement about appearance into a traceable quality question.
Link the specification to the intended process
Ontario's drinking-water design guidance treats coagulant type, concentration, mixing and downstream processes as connected design considerations. A specification review is therefore a screening step, not a replacement for a water-specific trial. Include the actual treatment objective and equipment when discussing a candidate grade.
Ask the supplier to distinguish a technical data sheet from a batch COA and from an application-specific approval. Check the issuing organization, product name, scope and currency of any approval presented. A generic file title or a certificate belonging to another grade does not resolve that question.
Questions about PAC purchasing
Is a higher Al2O3 value always the better purchase?
It may change delivered concentration, but it does not by itself determine treatment performance, handling suitability or total treatment requirements. Compare the stated product basis, the actual application and the evidence from a controlled trial.
Can the same basicity guarantee an identical result?
No. It is one specification among several. Keep product identity, water conditions and the full treatment train in the comparison. Agree on measurable acceptance criteria before converting a supplier discussion into an order.
Prepare a specification-based enquiry
Send the current TDS, a representative COA, your required form, use and destination. Mark which fields are mandatory. See PAC product information and clarification applications, or ask ENVO to discuss the required supply specification.
Related technical guides
- PAC Coagulation: Check Post-Dose pH and Alkalinity
- Cold-Water PAC Trials: Separate Floc Formation from Settling
Sources and scope
- USALCO, DelPAC 2020 product and technical-resource page
- Ontario, Design Guidelines: Treatment and Chemical Application
Sources checked on 30 October 2026. The comparison framework and illustration are original ENVO editorial material. They are not a plant case study, a product performance guarantee or a substitute for the applicable product label, operating procedure and local requirements.
