Foam is more than a nuisance — it carries solids over weirs, trips level instruments, fouls diffusers and creates a hygiene and safety hazard. Controlled antifoam dosing knocks foam down at a few mg/L, but the chemical is potent, shear-sensitive and easy to overdose. This is how we dose silicone and non-silicone defoamers accurately, only when and where they are needed.
Defoamers work at the gas–liquid interface, spreading a low-surface-tension film that destabilises foam lamellae so bubbles collapse. Because they act at the surface, a tiny dose — often 1–20 mg/L, applied as a short burst — clears a foam head that would otherwise carry over. The art is restraint: silicone defoamers persist and accumulate, can blind membranes downstream, and beyond the optimum actually stabilise foam. So antifoam is best dosed on demand — triggered by a foam/level switch or timed against the known foaming event — not continuously. In flotation specifically, see DAF foaming control.
| Type | Best for | Watch-outs |
|---|---|---|
| Silicone (PDMS) emulsions | Strong, persistent foam; aeration basins | Persists; can foul membranes if overdosed |
| Non-silicone (oil/ester) | Where silicone is prohibited (food/membrane) | Lower persistence; may need higher dose |
| Polyglycol / EO-PO | Process foam, fermentation | Temperature-dependent performance |
| Powder defoamers | Dry-feed applications | Require make-up — see dry dosing |
Foam probe, capacitance level or timer fires a measured burst — avoiding the continuous overdose that stabilises foam.
Viscous emulsions suit a peristaltic or progressive-cavity pump that won't shear or de-emulsify the product.
Surface spray bars clear a foam head fast; sub-surface injection prevents foam forming — often both are used.
Inline dilution carries a tiny neat dose to many spray points evenly without local overdose.
Gentle tank recirculation keeps emulsions homogeneous; suction kept off the tank floor.
Max-dose-per-event and daily-total limits in the PLC guard against runaway dosing on a stuck probe.
Filamentous and surfactant foam control on activated-sludge surfaces.
Process and CIP foam in high-organic food and beverage effluent.
Float-cell and saturator foam that disrupts skimming.
Pulp, textile and chemical process streams with surfactant loads.
Tell us where the foam is and what causes it — we will select the defoamer, the trigger and the dosing equipment to clear it without overdosing.
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