Adding defoamer is not simply a matter of "pouring it into the system." An improper dosing method can waste chemicals and may even cause secondary defects such as cratering, oil spots, and surface imperfections.
As a company with extensive experience in industrial water treatment and chemical additives, Laisen understands the importance of process details. To maximize the performance of a defoamer, four key aspects should be carefully controlled.
1. Identify the Optimal Dosing Point: High-Turbulence Areas
Do not pour defoamer directly onto a stagnant liquid surface, as this makes uniform dispersion difficult. The ideal dosing point is an area with strong agitation, high flow velocity, or sufficient turbulence.
Upstream of the Circulation Pump Suction or Static Mixer
The strong shear force generated by the flowing liquid can rapidly disperse the defoamer into fine active droplets, allowing it to distribute quickly and evenly throughout the foaming system.
High-Speed Agitation Zone
When using defoamer in a reactor, mixing tank, or paint-mixing tank, it should preferably be introduced near the impeller or into a high-shear zone. This allows the defoamer to contact and destabilize the foam as quickly as possible.
2. Choose the Right Dosing Method
Depending on the foam-generation pattern at the production site, three common dosing strategies can be used.
Batch or Intermittent Dosing
This method is suitable for applications where foam is generated intermittently or where the foam problem is relatively mild.
The calculated dosage can be added directly at the beginning of production, or a predetermined amount can be added periodically before significant foaming occurs.
Continuous Dosing
Continuous dosing is one of the most commonly used methods in industrial production.
A metering pump is used to continuously introduce a small amount of defoamer into the system. This compensates for the natural consumption or loss of defoamer and helps maintain long-lasting foam suppression.
It is particularly suitable for continuous production processes such as papermaking and wastewater treatment.
Automatic Dosing
For large chemical processing towers, fermentation tanks, and other large-scale equipment, foam detection probes can be installed.
When the system detects early signs of foaming, the automatic dosing system is triggered. When no foam is detected, dosing stops.
This intelligent dosing method can help reduce unnecessary chemical consumption and improve dosing efficiency.
3. Proper Dilution and Pre-Treatment
Many defoamer concentrates have relatively high viscosity, and direct application may result in uneven dispersion. However, dilution must be carried out carefully.
Prepare Only What Is Needed
Diluted defoamer emulsions may have limited stability and can separate or lose performance during prolonged storage.
Therefore, it is strongly recommended to prepare the diluted solution immediately before use and use it within the same day, rather than storing diluted defoamer for an extended period.
Use Room-Temperature, Low-Hardness Water
When dilution is required, use room-temperature tap water or other suitable low-hardness water, as recommended by the product supplier. Avoid using hot water.
High temperatures and excessive shear during dilution may destabilize certain emulsion systems and cause the defoamer to break, separate, or release oil.
Mix Thoroughly Before Use
The defoamer concentrate should be thoroughly mixed before use to ensure that the active components are uniformly distributed and to prevent settling.
For powdered defoamers, the product can generally be pre-dispersed in water or premixed with dry raw materials before being introduced into the process, depending on the manufacturer's recommended procedure.
4. Strictly Control Dosage and Dosing Stage
Small and Frequent Dosing — Avoid Overdosing
The dosage of a defoamer can vary significantly depending on the application and formulation. In many applications, the dosage may range from several parts per ten thousand to several parts per thousand, but the optimum dosage should be determined through laboratory or on-site testing.
Overdosing not only wastes chemicals but may also cause cratering, fisheyes, oil spots, and other serious surface defects. In some formulations, excessive defoamer may even adversely affect foam stability.
Stage-Wise Addition: The Two-Stage Method
For complex systems such as coatings, inks, and emulsified oils, a two-stage dosing strategy may be appropriate.
Stage 1 — Defoaming:
Add a fast-acting defoamer during high-speed grinding or the intermediate stage of synthesis to control and eliminate bubbles generated by strong shear.
Stage 2 — Foam Suppression:
Add a long-lasting foam-suppressing defoamer during final formulation or at a later stage to provide sustained foam control during storage and application.
Conclusion
The performance of a defoamer can vary significantly depending on the manufacturer, formulation, and application system.
Before large-scale production, it is recommended to conduct laboratory compatibility testing and dosage optimization using actual process conditions. This helps determine the most appropriate dosage and dosing method for the specific application.
Rather than simply selecting a product based on price, appearance, or a standard dosage, the optimal solution should be determined based on foam characteristics, process conditions, system compatibility, dosing point, dosing method, and actual application performance.
For professional technical support, Laisen can provide water quality analysis and sample testing to help customers identify a suitable defoamer and optimize the dosing program.
