Common Problems with Utrasonic Liquid Processing Equipment

What is Ultrasound?

Although sound is an auditory sensation, it is not always audible. The literal meaning of ultrasound is beyond sound; Sound above the human audible spectrum. The frequency of sound is the number of cycles of sound waves within one second. The frequency is measured in units called Hertz (Hz). Since 18 kHz per second (18000 Hz/cycle) is approximately the upper limit of human hearing, ultrasound refers to sound waves that exceed that frequency. 20 kHz is the most effective frequency for liquid handling applications.

 

What is the difference between an ultrasonic processor and an ultrasonic bath?

Due to many factors, the ultrasound intensity and power in the bath are low, position dependent, and inconsistent. Using an ultrasonic processor, due to the high, concentrated, and adjustable energy intensity at the top of the tool, the processing speed is significantly accelerated and the repeatability is high.

 

20KHZ or 40KHZ?

40 kHz is commonly used for ultrasonic cleaning and atomization, as the droplet size at this frequency is half of the droplet size generated at 20 kHz. However, the preferred frequency for most ultrasonic liquid treatment applications is 20 kHz, as the amplitude at the top of the tool head and the resulting cavitation are more effective for liquid treatment. 40kHz may be effective for small batches and some applications with shorter durations.

 

Are there any limitations to ultrasonic processing?

Yes - viscosity, temperature, and liquid characteristics. As the viscosity of the material increases, its ability to transmit vibrations decreases. Usually, the maximum viscosity that can effectively process materials is 4000 CPS. For standard systems, the actual upper temperature limit is approximately 65 ° C. Solid tool heads can be used for aqueous solutions and low surface tension liquids (such as solvents), but replaceable tool heads are only used for aqueous samples.

 

Which instrument should I use?

The 500 and 800W devices are the most versatile as they can handle both large and small volumes - from micro tips as small as 250 μ l to 1 liter of 1 "(25mm) probes. In addition, when used together with continuous flow tanks, they can process many liters per hour on the basis of flow. If your sample volume is small, a 500W device may be the best choice. 1500 or 2500 watt devices are recommended for large-scale and industrial applications.

 

Is it a replaceable or sturdy tool head?

The replaceable tool head has a threaded end, which can be unscrewed and replaced when the tool head wears out. The replacement tool head is only used for water containing samples. If you sonicate a solution containing organic solvents, alcohol, or any low surface tension liquid, the liquid will seep into the interior of the threaded tool head (regardless of how tight the connection is). Once the liquid enters the tool head, it will loosen and cause the system to display an overload error. If the application requires solvents or low surface tension liquids, solid probes must be used. Solid probes can be used for any type of liquid. Please note that all micro prompts are solid. Only probes with a diameter of 1/2 "or larger can replace the tool head.

 

Which tool head is most suitable for my application?

The larger the diameter of the tool head, the higher the amplitude, and the larger the volume that can be processed. A smaller tool head is required to fit into a smaller container.

 

How deep should the tool head be inserted?

If the depth of immersion of the tool head is not sufficient, the sample will bubble. If the tool head is immersed too deeply, the sample will not circulate effectively. Setting the amplitude too high can also cause bubbling. All the situations described will lead to prolonged processing time and poor results. Adjust the depth of the tool head to avoid splashing and bubbling, while still maintaining vigorous sample mixing.

 

Can probes be manufactured to any length?

may not. The tool head resonates at a specific frequency (half wavelength or a multiple of half wavelength). The 20KHz tool head is approximately 5 inches (127 millimeters) long and can be extended in increments of 5 inches (127 millimeters).

 

Power display and amplitude setting?

Power is a measure of the electrical energy transmitted to the transducer. It is measured in watts and displayed on the screen of the ultrasonic instrument. At the transducer, electrical energy is converted into mechanical energy. It achieves this by exciting piezoelectric crystals to move longitudinally within the transducer. This conversion from electrical energy to mechanical energy causes the movement through the tool head, resulting in the top moving up and down.

 

The distance of one up and down movement is called amplitude. Adjustable amplitude. Each tool head has a maximum amplitude value. For example, in a 1/2 "diameter tool head set to 100%, the tool head will reach an amplitude of approximately 115 μ m. When set to 50%, the amplitude is approximately 57 μ m. Please note that this value is an approximate value and not completely linear.

 

There is a direct relationship between amplitude and intensity. If you operate under low amplitude settings, you will be provided with low-intensity ultrasound treatment. If you operate under high amplitude settings, you will receive high-intensity ultrasound treatment. In order to reproduce the results, the amplitude setting, temperature, viscosity, and volume of the sample need to be consistent parameters. When attempting to reproduce the results of ultrasonic treatment, amplitude rather than power is the most critical factor.

 

Power has a variable relationship with amplitude/intensity. For example, compared to viscous samples such as honey, ultrasonic treatment of water at a 50% setting requires less power. For these two samples, the amplitude/intensity is the same, but the power/wattage will be different because viscous samples require more watts to drive the tool head. Adhesive samples will impose heavier loads on the tool pair, so their system must work harder to vibrate up and down with the same intensity. The small fluctuations in wattage displayed during ultrasonic treatment are normal.