How to Pick the Best Ultrasonic Cleaner:

How to Pick the Best Ultrasonic Cleaner

Selecting the best ultrasonic cleaner for your job should involve the same careful thought processes you’d go through when making other important purchasing decisions – such as an automobile or computer. What features are important to you?  Balancing “must have” with “nice to have” applies to any significant purchase. 

This post provides 10 tips on how to select the best ultrasonic cleaner by explaining features that may (or may not) be useful to your particular circumstances. It covers:

When you arm yourself with answers to these points you are well on the way to select the best ultrasonic cleaner to do the jobs you need to do at the best price.

One of, if not the first, ultrasonic cleaner specification is:

1. What ultrasonic cleaner tank dimensions are required?

Put another way, how large are the parts being cleaned or the number of samples processed? 

  • Measure the dimensions of largest parts to be cleaned (or number of flasks or beakers to be processed)
  • Select equipment having a tank that will accommodate them 

In addition, pay attention to the dimensions of the parts or sample baskets.  Ultrasonic cleaner baskets are discussed in tip 3 below.

You’ll also need to know the working depth of the cleaning fluid as it relates to the size of parts you’re cleaning. 

The working depth is the distance from the inside bottom surface of the basket to the surface of the liquid in a filled ultrasonic cleaner tank. 

This is important because parts being cleaned must be fully immersed in the liquid.  Sample prep, on the other hand, may require less depth because the entire container need not be immersed in the solution.  Special units are designed for sample prep operations.

Product specs for benchtop ultrasonic cleaners may not include this information.  If they do not, feel free to ask the manufacturer or supplier.  On the other hand, manufacturers of large industrial tanks often report both tank depth and working depth.

For more on this see our post on ultrasonic cleaner tank size.

2. How are you using your ultrasonic cleaning equipment?

The best ultrasonic cleaners do a lot more than clean parts such as gears, carburetors, PCB boards and surgical instruments.  In the lab they are broadly employed to degas solvents, disperse nanoparticles, and emulsify, dissolve, disperse and otherwise prepare lab samples. 

If you are cleaning parts, to get started you need to consider the following before picking your best ultrasonic cleaner:

  • Type of contamination to be removed. There’s a big difference, as you can imagine, between removing coolant from machined parts, varnish deposits from a carburetor, ink from printing rolls, and blood and tissue residues from surgical instruments.
  • The composition of products being cleaned. Different parameters apply to cleaning aircraft engine components and glass capillaries. You’ll need a compatible ultrasonic cleaning frequency and correct cleaning solution formulation.
  • How will the parts be used after cleaning?
  • How do you define ‘clean’?
  • Will you be cleaning batches or individual parts?
  • Component size and weight

Once you define exactly what you’re trying to accomplish the following points will help narrow down your choices to select your best ultrasonic cleaner.  Then it’s time to contact Tovatech for specific recommendations.

3. What ultrasonic cleaner baskets are best?

Ultrasonic cleaner baskets and accessories

Baskets support parts and sample containers in an ultrasonic cleaner.  They affect cleaning and sample processing efficiency and, importantly, protect tanks from damage. 

Baskets with insulated handles facilitate placing and removing parts being cleaned in hot liquid.  They also keep parts, flasks, and beakers off the tank bottom where they suppress vibration and lower cleaning effectiveness. 

In terms of tank life, keep in mind that the bottom of the tank is a vibrating membrane. Any solid item, particularly a metal part or metal filings, can act as a drill while the ultrasound is operating.  Over time this can wear a hole in the tank.  That’s a good enough reason to use baskets.

Some baskets hang on the tank rim; others are equipped with rubber-coated feet positioned near the corners of the tank bottom where vibration is at a minimum. Fine mesh baskets for small parts can be positioned in beakers or standard baskets.

You’ll find a bit more on this in our post on ultrasonic cleaner basket specification. That post connects to a related post for additional background.

4. How to select the best ultrasonic cleaner frequency?

Ultrasonic cleaner frequency is produced by generator-powered transducers bonded to the bottom of the tank. They vibrate in kilohertz (kHz or thousands of cycles per second).

Elma XTRA ST Ultrasonic Cleaner
Elma xtra ST

Most ultrasonic cleaners operate between 35 and 45 kHz.  This frequency range is well suited to the vast majority of cleaning tasks. Sample prep is often accomplished with units operating at 37 kHz.  A candidate for the best ultrasonic cleaner for this application is the microprocessor-controlled Elma S150.

A lower frequency such as 25 kHz produces larger cavitation bubbles. When these bubbles implode, they release a larger amount of cleaning energy. The best ultrasonic cleaner for coarse cleaning such as removal of lapping abrasives or polishing paste will operate at a lower frequency to be more effective. 

Note that the lower the frequency, the louder the cleaning operation. Sound-deadening tank lids with insulation are a good idea when operating at 25 kHz. Another useful accessory is a noise-protection box in which to place the unit. 

A higher ultrasonic cleaning frequency produces smaller cavitation bubbles. These cover fine-featured complex surfaces more thoroughly and are gentler than low frequencies. 

For fine cleaning of very delicate jewelry, electronics, and soft metals with polished surfaces consider a unit operating at 80 – 130 kHz. If you are cleaning capillary tubes or spectrophotometer cuvettes your best ultrasonic cleaner will operate at 80 kHz or higher.

If you are cleaning a variety of materials, consider a dual-frequency ultrasonic cleaner. An example is the Elmasonic xtra ST that can be set to 25 kHz for basic cleaning and to 45 kHz for fine cleaning.  Models in the TI-H series operate at 25/45 and 35/130 kHz.

5. How to Manage Ultrasonic Cleaning Solution Temperature

Heat is produced by ultrasonic cavitation and many cleaning tasks are faster and more efficient when using a heated solution.  For example, a hot cleaning solution is best for removing oils, machining coolants and a whole host of other contaminants from just about any surface you can think of.

If this is the case for your requirements your best ultrasonic cleaner can improve throughput by using thermostat-controlled heaters. Examples are the Elmasonic E Plus, S and P series benchtop ultrasonic cleaners. These can be adjusted in increments to 80⁰C.

Please note that above 80⁰C cavitation is inhibited and cleaning efficiency levels off.

Some cleaning operations are not enhanced by a heated solution. An example is removing blood from surgical instruments. Another example is cleaning printed circuit boards, which can be warped or otherwise damaged if solutions are too hot. Cooling coils are available as accessories to help control cleaning solution temperature.

Other Useful Ultrasonic Cleaner Features

Ultrasonic cleaning operations benefit from features available in many models. Here are brief descriptions.

6. How does degas mode in ultrasonic cleaning work?

Freshly prepared ultrasonic cleaning solutions contain entrained air that inhibits cavitation.

Trapped air can be removed two ways – letting the equipment operate for a period of time without a load or specifying a cleaner with a degas mode for faster results. 

A degas mode does its job by switching on and off causing air bubbles to coalesce, rise to the surface and burst.  

7. What are the benefits of the sweep mode with ultrasonic cleaners?

Sweep provides a slight ± fluctuation in the cleaner’s ultrasonic frequency and serves to even out the cleaning action.  This avoids what are called

  • “Hot spots” or more intense and possibly damaging cavitation action
  • “Dead zones” or no cleaning action, and
  • Harmonic vibrations that can damage delicate parts such as PCBs.  

The opposite “normal” mode provides no fluctuation and is chiefly used for sample preparation in an ultrasonic cleaner.  Your best ultrasonic cleaner may be one that allows you to select sweep and normal modes, examples being the Elma S and P series.

8. How to boost ultrasonic power with pulse mode?

If you are cleaning products with particularly tenacious contaminants specify an ultrasonic cleaner equipped with a pulse mode. Pulse mode boosts ultrasonic power to 20% on some models to remove stubborn contaminants. 

If you are degassing solvents select a model that has either a degas mode or a pulse mode.  An ultrasonic cleaner without these modes will not only degas your solvents but will do so at a slower rate. 

Pulse and sweep cannot operate simultaneously but equipment is available that automatically switches between the two.  An example is the Elmasonic x-tra ST series. The ultrasonic performance is temporarily increased while the even ultrasonic sound field distribution in the bath enhances the cleaning effect.

9. What ultrasonic power is required?

When an ultrasonic cleaner is running electrical power is consumed evenly but it is released in intervals to create the sound waves that shape the ultrasonic signal. 

Some manufacturers report ultrasonic peak power, others report average power, and some report both. When comparing equipment, you must compare based on the same criterion otherwise you’d be comparing apples with oranges.

While more power usually indicates faster and more effective cleaning, more power is not always better.  Too much power can damage electronic parts, the surface finish on a soft metal (e.g., aluminum), and other delicate items. 

For cleaning extremely sensitive items your best ultrasonic cleaner should be equipped with adjustable power. Examples are the Elma TI-H and P series

Keep in mind that the larger the volume of solution, the more ultrasonic power will be needed for cleaning. Most cleaners run at an average power of 50 to 100 watts per gallon, so the larger the tank the more power you need.

Don’t attempt to increase the effective power of an ultrasonic cleaner by under-filling the tank.  Ultrasonic cleaner generators that power transducers are tuned to a particular fill level.  Operating the unit with less fluid can damage the generator and will result in less than optimized cleaning.

10. What ultrasonic cleaning accessories are available?

A variety of accessories are available to support the use of ultrasonic cleaners. Blending, dissolving and dispersing are facilitated when suspending samples in a water bath with a surfactant. Use Erlenmeyer flask holders, flask

A variety of accessories are available to support the use of ultrasonic cleaners. Blending, dissolving, and dispersing are facilitated when suspending samples in a water bath with a surfactant.  Use Erlenmeyer flask holders, flask clamps, test tube holders or specially designed lids to hold beakers.   Beakers and beaker holders are also useful when cleaning small parts with volatile media.  If high bath temperatures are a concern, a cooling coil attached to a cold water line serves as a heat exchanger to prevent the bath from overheating.  See our post on ultrasonic cleaner accessories for more on this topic.

11. What is the correct ultrasonic cleaning solution?

The correct cleaning solution chemistry is as important as ultrasonic frequency, power and other points covered in this guide to help you select your best ultrasonic cleaner. 

Our article in R&D magazine provides guidance on cleaning chemical selection. Tovatech offers a wide variety of ultrasonic cleaning solutions along with advice from our experts to help you make the right selection.

Browse Our Popular Benchtop Ultrasonic Cleaners

Elma E Plus Series
Routine Cleaning & Mixing
– Sweep mode for uniform cleaning
– Pulse for mixing & degassing
– Timer: 1-30 min or continuous
– Temperature settings up to 80° C
– 9 tank sizes from 0.25 to 7.5 gal

Elma P Series
Advanced, Dual Frequency, Variable Power
– 4 Modes for cleaning, mixing, degassing
– Dual frequency: 37 kHz and 80 kHz
– Timer and heater up to 80° C
– 6 tank sizes from 0.75 to 7.5 gal

Need help? Call or Chat with Us

We have not covered all points to selecting an ultrasonic cleaner in this post.  The professionals at Tovatech are ready to get into the nitty-gritty if you have particularly challenging cleaning or sample prep requirements. Give us a minute and we’ll answer your questions.

About Rachel Kohn

So how did an MIT Ph.D. end up selling refrigerators? When I figured out that a lot more scientists buy lab refrigerators than innovative leading-edge instruments. I hope that my many years of lab experience will help you find the right equipment for your work. Before co-founding Tovatech I worked in business development and project management at Smiths Detection, Photon-X, Cardinal Health, and Hoechst Celanese. And before that I spent 12 years as an R&D chemist at Hoechst Celanese and Aventis working on advanced drug delivery systems, polymer films and membranes, optical disks, and polysaccharides. Some day, eventually, I’ll make enough money to develop an innovative technology that will change the world. Read More