Progressive dilution of concentrated polyacrylamide or polyDADMAC from stock concentration (up to 40% and 1000 cP) to diluted working solution. Two-stage dilution is standard.
Stage 1: turbulent KE mixer at controlled velocity (avoid exceeding maximum shear rate (s⁻¹)). Stage 2: near-laminar SX for final homogenisation at Coefficient of Variation (CoV) ≤0.05. Maximum shear rate (s⁻¹) per polymer supplier specification. Ageing time 20–60 min for full hydration.
Preferred MOC: UHMWPE or FRP for cationic polyacrylamide (fouls stainless steel). 316SS acceptable for anionic PAM. Avoid iron-based materials.
Two-stage design essential. Injection velocity must not exceed maximum shear rate (s⁻¹) specified by polymer supplier. KE velocity <0.5 m/s for high-MW polymers. Stage 2 SX at low velocity.