Applications · Water Treatment

STATIC MIXER FOR PH CONTROL & ACID-BASE NEUTRALISATION

Inline static mixing of acid or caustic into a process stream ensures uniform pH at the measurement point, preventing control loop instability. The low additive volume fraction (typically 0.01–0.5% v/v) demands a well-positioned injection quill and sufficient mixing length to achieve Coefficient of Variation (CoV) ≤0.05 upstream of the pH probe.

Turbulent | Low Viscosity | Chemical Dosing
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Coefficient of Variation (CoV) ≤0.05
Key Parameter 1
3–5D Mix Length
Key Parameter 2
15–30% Reagent Saving
Key Parameter 3
DN25–DN1200
Key Parameter 4
Process Scheme
Feed Water
Flow Meter
Acid / Caustic
Static Mixer
pH Transmitter
To Process

Mixing Criteria

Coefficient of Variation (CoV) ≤0.05 at mixer discharge or within 3–5D downstream. Injection ratio typically 0.01–0.5% v/v (acid to main flow). Injection velocity ratio 1.5–3:1 jet-to-pipe velocity. Minimum 6 elements for 10:1 turndown. Velocity Gradient (G-value) not critical — concentration uniformity governs.

Typical Viscosity
0.5–5 cP (centipoise) (dilute aqueous)
Reynolds Number (Re)
Reynolds Number (Re) 5,000–500,000 (turbulent)

Material & Special Requirements

Preferred MOC: 316 Stainless Steel standard. FRP or PVDF-lined for fluorosilicic acid (H₂SiF₆) and aggressive mineral acids. Rubber-lined CS for lime (Calcium Hydroxide / Lime (Ca(OH)₂)) slurry duty.

Injection quill mandatory — centreline penetration, angled 45° downstream. KE-R removable elements for lime and scale-forming reagents. Wide turndown (10:1) — verify CoV at minimum flow.

Recommended Mixer
KE Series — Helical Element
Kenics-equivalent. 180° RH/LH helical elements joined at 90°. Halves striation thickness per element. Works laminar to turbulent. Best general-purpose choice.
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