Why Do Ultrasonic Cleaners De-gas? Causes, Effects, and Solutions

Ultrasonic cleaning machines are widely used for their ability to remove dirt, contaminants, and particles from surfaces efficiently. However, one common issue encountered during the cleaning process is de-gassing, where air bubbles are released from the cleaning liquid. This phenomenon can significantly affect cleaning performance and efficiency. In this article, we will explore the causes of de-gassing, its impact on ultrasonic cleaning systems, and discuss solutions to mitigate the issue.

I. Understanding De-gassing in Ultrasonic Cleaners

De-gassing refers to the release of dissolved gases, primarily air, from the cleaning liquid due to ultrasonic cavitation. Ultrasonic cleaning relies on high-frequency sound waves to create microscopic bubbles in the cleaning solution. These bubbles, formed during the cavitation process, rapidly expand and collapse, creating intense energy that helps dislodge contaminants from surfaces. However, air bubbles introduced into the system can interfere with this process, reducing cleaning effectiveness.

II. Causes of De-gassing

1. Dissolved Air in Cleaning Solution

   • The primary cause of de-gassing is dissolved air or gas present in the cleaning solution.
   • When ultrasonic waves create cavitation bubbles, dissolved air is released into the solution. This air buildup can accumulate and cause interference with the ultrasonic waves.

2. Solution Temperature

   • As temperature increases, the solubility of gases decreases. This means warmer cleaning solutions are more likely to release air bubbles.
   • Higher temperatures reduce the liquid’s ability to hold dissolved air, leading to more air being released into the cleaning tank.

3. Improper Liquid Filling Levels

   • Insufficient liquid volume can result in air entrapment, creating pockets of air that prevent effective cleaning.
   • Inadequate liquid levels exacerbate the formation of air bubbles due to reduced surface area and increased ultrasonic wave intensity.

4. Contaminated Water or Cleaning Solutions

   • Cleaning solutions containing impurities, dust, or contaminants can further contribute to air bubbles, as they release gases into the solution.
   • The presence of particles or contaminants can also act as nucleation sites, facilitating the formation of bubbles.

5. Excessive Cleaning Power

   • Overly intense ultrasonic power can accelerate cavitation activity, which enhances the release of air bubbles into the cleaning solution.
   • High energy levels may also lead to unstable cavitation bubbles, increasing the likelihood of air entrapment.

III. Effects of De-gassing on Ultrasonic Cleaning

1. Reduced Cleaning Efficiency

   • Air bubbles interfere with the cavitation process, reducing the intensity and effectiveness of ultrasonic cleaning.
   • The bubbles act as a physical barrier between the cleaning waves and the contaminants, preventing thorough cleaning of surfaces.

2. Inconsistent Cleaning Results

   • Areas affected by air bubbles may remain partially or entirely uncleaned, leading to inconsistent cleaning outcomes.
   • Certain regions might retain contaminants due to the reduced energy transfer caused by the presence of air pockets.

3. Increased Cleaning Time

   • Cleaning systems affected by de-gassing tend to require longer cleaning times to achieve the same level of cleanliness, as air bubbles slow down the cleaning process.

4. Damage to Equipment

   • Air bubbles can create pressure within the cleaning tank, potentially leading to mechanical stress on components such as transducers, causing wear and tear or even equipment failure.
   • Continuous air bubble formation can also reduce the lifespan of ultrasonic equipment by increasing the strain on internal components.

IV. Solutions to Mitigate De-gassing

1. Use of De-gassing Additives

   • Adding chemical de-gassing agents (such as surfactants or anti-foaming agents) to the cleaning solution can help reduce the release of dissolved air.
   • These additives break surface tension and minimize air bubble formation, ensuring more effective ultrasonic cleaning.

2. Temperature Control

   • Maintaining the cleaning solution at an optimal temperature range (usually between 40°C to 60°C) reduces the solubility of air, minimizing de-gassing.
   • Proper cooling or heating mechanisms should be employed to stabilize the liquid temperature.

3. Proper Liquid Level Management

   • Ensuring the correct liquid volume in the cleaning tank can prevent air entrapment. The liquid should cover the cleaning objects completely, reducing the chances of air pockets.

4. Regular Maintenance and Cleaning

   • Ensuring the ultrasonic cleaner and the cleaning tank are clean and free of debris or contaminants prevents the release of gases into the cleaning solution.
   • Regularly check for clogged filters, build-up of contaminants, and other obstructions that could promote air bubble formation.

5. Optimize Ultrasonic Power Settings

   • Using appropriate ultrasonic power levels prevents excessive cavitation, reducing air bubble formation.
   • Manufacturers typically provide recommended settings that optimize the balance between cavitation intensity and energy efficiency.

V. Conclusion

De-gassing in ultrasonic cleaners is a common challenge that can negatively impact cleaning efficiency and equipment performance. By understanding the root causes of air bubble formation and adopting effective solutions such as temperature control, de-gassing agents, and proper maintenance practices, users can mitigate this issue. Implementing these strategies ensures that ultrasonic cleaners maintain optimal cleaning performance, enhancing overall efficiency and safety.