Introduction
Never buy a container of PAC or PAM without testing a sample first. A 1-2 kg free sample can prevent a $5,000-15,000 mistake — yet many buyers skip this step or do it incorrectly. This guide covers how to request samples professionally, design an evaluation that predicts full-scale performance, and avoid common pitfalls that make sample tests misleading.
How to Request Samples (The Right Way)
Information to Provide to the Supplier
A vague “send me PAC samples” request will get you whatever the supplier has in stock — not necessarily what you need. Provide:
- Application details: What are you treating? (e.g., “textile dye wastewater, mainly reactive dyes, 800 m3/day”). This helps the supplier recommend the right PAC basicity and PAM type
- Key water quality parameters: pH, turbidity, COD, TSS, temperature. Actual numbers, not “it’s dirty.” A photo of the wastewater is helpful
- Current treatment: What chemical and dose are you using now? What’s working and what’s not?
- Treatment targets: What discharge limits are you trying to meet? (e.g., “need to reduce COD from 1,200 to <200 mg/L")
- Your location: For shipping cost estimation and logistics planning
- Annual consumption (approximate): Helps the supplier understand if you’re a 5-ton/year or 500-ton/year opportunity — affects pricing and attention
What to Expect from a Professional Supplier
A legitimate supplier will:
- Provide COA for the specific sample they’re sending (not a generic brochure)
- Ask about your application before recommending a product (not just send “our standard PAC”)
- Offer technical guidance on jar test procedure for their product
- Ship via international courier (DHL/FedEx/UPS) within 3-7 business days of your request
- Follow up after you receive the sample to answer questions
A supplier that sends a sample without asking any questions about your application, provides no COA, or takes weeks to ship is unlikely to provide good service on bulk orders.
Sample Evaluation Program Design
Phase 1: Sample Reception and Documentation
- Photograph the sample upon receipt — packaging, label, any damage
- Record: date received, sample weight, appearance (color, powder/flake/bead), COA data from supplier
- Store properly: Sealed container, cool (<30°C), dry place. PAC and PAM both absorb moisture — opened sample degrades within weeks
Phase 2: Jar Test — The Core Evaluation
Follow the complete jar test procedure in our dedicated guide (article #D2). For sample evaluation specifically:
- Always include a control: Your current coagulant at your current dose. You’re comparing the new product against what you use now, not against nothing
- Test at least 5 doses: 50, 100, 200, 300, 500 mg/L (adjust range based on your current dose). A 1-dose or 2-dose test won’t show the full performance curve
- Use actual plant wastewater, not synthetic: Synthetic test water (kaolin suspension) tells you nothing about how PAC performs on real textile/dairy/mining wastewater with its unique organic and ionic composition
- Sample freshly: Test within 2 hours of collecting the wastewater sample. Stored samples change (biodegradation, pH drift, particle settling)
- Replicate: Run triplicates at each dose. Single jar tests are unreliable — the coefficient of variation for jar tests is typically 10-20%
- Dissolution time: Does it dissolve completely in the time your make-down system allows?
- Solution stability: Does the stock solution stay effective over the time between preparation and dosing? Check turbidity removal with freshly prepared vs 24-hour-old solution
- Filterability: If you have MMF/UF after coagulation, filter PAC-treated water through a 1um filter and measure flux. Some PACs produce slimy flocs that blind filters faster than others
- Foaming: Does the PAC or PAM solution foam excessively in your make-down tank? Some products contain surfactants from the manufacturing process
- Pilot trial quantity: 1-5 tons (2-10 drums or 40-200 bags). Enough to run your plant for 1-2 weeks at normal dosing
- Pilot trial objectives: 1) Confirm jar test results translate to full scale. 2) Verify compatibility with your dosing equipment. 3) Train operators on any differences from current chemical. 4) Measure actual sludge production at full scale
- Pilot trial monitoring: Daily measurement of treated water quality (turbidity, COD, pH) and sludge production. Compare with the week before the trial (your current chemical’s baseline)
- Pilot trial go/no-go criteria: Treatment targets met? Dosing equipment handling the product? Operators comfortable with the change? Sludge production as expected? If yes to all, proceed to bulk purchase
- Does it work? Meets treatment targets at an acceptable dose
- Is it consistent? Production sample performs like the initial sample
- Is the TCO competitive? Not the cheapest per ton, but the cheapest per m3 treated (see our TCO comparison guide)
- Is the supplier reliable? Responsive communication, proper documentation, professional packaging, production capacity matching your needs
Phase 3: Measured Outcomes
| Parameter | How to Measure | What to Compare |
|---|---|---|
| Supernatant turbidity (NTU) | Turbidimeter, mid-depth sample after 15 min settling | Turbidity at each dose for sample vs current product. Lower is better, but target is meeting your limit, not the absolute lowest |
| Floc size and settling rate | Visual observation + ruler. Record time for floc blanket to settle 50% | Larger, faster-settling flocs = shorter clarifier retention time needed |
| Sludge volume | Measure settled sludge volume after 30 min in Imhoff cone or graduated cylinder | Lower sludge volume = lower disposal cost. Compare mL sludge per L treated for sample vs current product |
| pH change | pH meter before and after treatment | Less pH change = less pH adjustment chemical needed |
| COD removal (if applicable) | COD test on supernatant (filtered through 0.45um) | Higher COD removal at equivalent dose = better performance |
| Residual Al or Fe | Al or Fe test kit or send to lab | Lower residual metal = less carryover to downstream processes or discharge |
Phase 4: Solution Preparation and Handling Test
Jar test performance is one dimension. The product must also work in your plant’s equipment:
Scale-Up from Sample to Pilot Trial
If the jar test is successful, the next step is a pilot trial — NOT a full container purchase:
Red Flags in Sample Evaluation
| Red Flag | What It Means | Action |
|---|---|---|
| Sample performs dramatically better than COA numbers suggest | Sample may be a “special batch” not representative of production. This is the “golden sample” trick — a specially prepared high-quality sample that bulk shipments won’t match | Request a production sample taken from an actual production batch, not a lab-prepared sample. Compare COAs |
| Supplier can’t or won’t provide sample COA | They don’t test their products, or the sample is from an unknown batch | Reject supplier. No COA = no quality control |
| Sample arrives poorly packaged (torn bag, no label, no MSDS) | Careless about details. How will they package a 20-ton container? | Proceed with caution. Ask for photos of actual export packaging |
| Supplier pressures you to order bulk within days of receiving sample | They want the sale before you’ve had time to properly evaluate. Legitimate suppliers want you to test thoroughly — they’re confident in their quality | Take your time. A legitimate supplier will still be there in 2-4 weeks when your evaluation is done |
| PAC sample has unusual color (gray, reddish, very dark brown) | Contamination with iron, other metals, or organic residues | Test for heavy metals before using. Red/gray PAC = likely iron or raw material contamination |
Making the Final Decision
After jar testing, pilot trial, and quality verification, the decision comes down to:
HydroChemix provides free 1-2 kg product samples with complete COA documentation, delivered by international courier within 7 business days. Every sample comes from an actual production batch — the quality you test is the quality you’ll receive in bulk. Contact jingshuicc@gmail.com with your application details to request a sample and technical consultation.