Introduction
When sourcing Poly Aluminium Chloride (PAC) from manufacturers, verifying product quality before bulk purchase is essential. Poor quality PAC can lead to ineffective treatment, higher chemical costs, and compliance issues. This guide covers the key parameters to test and how to evaluate PAC suppliers.
Key Quality Parameters
1. Al2O3 Content (Aluminium Oxide)
The active ingredient in PAC. Premium spray dried PAC should contain 28-31% Al2O3. Below 26% indicates diluted or low-grade product. Test method: GB 15892-2009 or customer-specified titration.
2. Basicity
Basicity determines the degree of pre-hydrolysis and directly affects coagulation efficiency. For industrial applications, 30-85% is the working range, with 30% being the standard grade. Higher basicity (>70%) is available for specialized applications. Test method: chemical titration per GB/T 22627.
3. Water Insolubles
The percentage of material that does not dissolve in water. Premium PAC should have <0.5% water insolubles. Higher values (>1%) indicate impurities or poor manufacturing quality. Test method: gravimetric analysis after dissolution and filtration.
4. pH (1% Solution)
Affects handling and dosing system compatibility. Typical range: pH 3.5-5.0 for a 1% aqueous solution. Values outside this range may indicate formulation issues.
5. Bulk Density
Important for shipping cost and storage. Spray dried PAC: 0.65-0.75 g/cm3. Significant deviation may indicate inconsistent production.
6. Heavy Metals Content
Critical for drinking water applications. Premium grades meet NSF/ANSI 60 certification with: Arsenic <5 mg/kg, Lead <10 mg/kg, Cadmium <2 mg/kg, Chromium <10 mg/kg, Mercury <0.2 mg/kg.
Bench Testing: Jar Test Protocol
Before bulk purchase, always conduct a jar test with your actual raw water:
- Prepare a 1% PAC solution (10g PAC in 1L distilled water)
- Fill 6 beakers with 1L raw water each
- Add PAC at varying doses: 50, 100, 200, 300, 400, 500 mg/L
- Rapid mix at 150 rpm for 1 minute
- Slow mix at 30 rpm for 15 minutes
- Settle for 15 minutes
- Measure supernatant turbidity, COD, color, pH
- Optimal dose is the lowest dose achieving target water quality
Supplier Evaluation Checklist
- Certificate of Analysis (COA) — provided with every shipment?
- Third-party testing — SGS, Bureau Veritas, or Intertek available?
- Production consistency — batch-to-batch quality records?
- Sample policy — willing to provide 1-2 kg free samples for testing?
- Factory audit — can you visit or arrange third-party inspection?
- Packaging integrity — moisture-resistant bags, proper sealing?
- Shipping reliability — regular container loads to your port?
- Technical support — dosing recommendations and after-sales service?
Red Flags to Watch For
- Refusing to provide COA or samples
- Al2O3 content varies significantly between batches
- Water insolubles consistently above 1%
- Unusual color (PAC should be white to pale yellow powder)
- Clumping or hardening in packaging (indicates moisture contamination)
- Price significantly below market without explanation
Hydrochemix Chemicals provides COA with every shipment, supports third-party testing (SGS/BV), and offers free 1-2 kg samples for bench testing. Contact jingshuicc@gmail.com to request your sample.