Common Problems with Ultrasonic Liquid Treatment Equipment

What is ultrasound?

Although sound is a perceptual sensation, it is not always audible. Ultrasound literally means transcending sound; Sound above the human audible spectrum. The frequency of sound is the number of cycles of sound waves within one second. 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 (sound waves) that exceeds that frequency. 20 kHz is the most effective frequency for liquid processing applications.

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

Due to many factors, the ultrasonic intensity and power inside the bath are low, position dependent, and inconsistent. Using an ultrasonic processor, due to the high energy intensity, concentration, and adjustability 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 frequency chosen for most ultrasonic liquid processing applications is 20 kHz, as the amplitude at the top of the tool and the resulting cavitation are more effective for liquid processing. 40kHz may be effective for small batches and some applications with shorter durations.

 

 

Are there any limitations to ultrasonic machining?

Yes - viscosity, temperature, and liquid properties. 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 with replaceable tool heads, they are only used for aqueous samples.

What kind of instrument should I use?

The 500 and 800W devices are the most versatile as they can handle both large and small volumes - as small as 250 μ L's micro tip, up to 1 liter of 1 "(25mm) probe. In addition, when used in conjunction with continuous flow pools, they can process many liters per hour on top of the flow. If your sample volume is very small, a 500W device may be the best choice. 1500 or 2500 watt devices are recommended for large-scale and industrial applications.

A replaceable or sturdy tool head?

The replaceable tool head has a threaded end, which can be unscrewed and replaced when the tool head is worn. The replacement tool head is only used for water containing samples. If you perform ultrasonic treatment on 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 ½" Probes with a diameter or larger can have replaceable tool heads.

Which tool head is most suitable for my application?

The larger the diameter of the tool head and the higher the amplitude, 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 the tool head immersion is not enough, the sample will bubble. If the tool head is immersed too deeply, the sample will not be able to circulate effectively. Setting the amplitude too high can also cause foaming. All situations described can lead to extended processing time and poor results. Adjust the depth of the tool head to avoid splashing and foaming, while still maintaining vigorous sample mixing.

 

 

Can probes be manufactured to any length?

No, it's not possible. The tool head resonates at a specific frequency (half wavelength or multiples 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 a transducer. It is measured in watts and displayed on the screen of the ultrasound 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 traveled up and down in one movement is called the amplitude. The amplitude is adjustable. Each tool head has a maximum amplitude value. For example, when set to 100% ½" In the diameter tool head, the tool head will reach approximately 115 μ The amplitude of m. When set to 50%, the amplitude is approximately 57 μ M. Please note that this value is approximate rather than completely linear.

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

There is a variable relationship between power and amplitude/intensity. For example, compared to sticky 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. Sticky samples will impose heavier loads on the tool pairs, so their systems must work harder to vibrate up and down with the same intensity. The small fluctuations in wattage display during ultrasonic treatment are normal.