Basically Costs, even though the technology has been around for awhile, even though the initial cost are coming down, it is still high. I have designed industrial COP ("Clean Out of Place" which is basically a large tub with ultra sonics and recirculation to wash large items in) units for the food and dairy using ultrasonics and have seen them in industry. but until costs come down farther so it is competive it will still be a wait.

Plus there are some draw backs to Ultra sonics. such as the frequency used 20,000 hertz. if any metal is touching metal fretting can occur, or plastic, polymer such as Tupperware can absorb the energy. what good is that.

So yes its not totally forgotten, but there is still some development left to improve.....

High temps in conventional dishwashers sterilize cookware and food-processing items, but ultrasonic dishwashers merely clean - they do not sterilize.

Thats not entirely correct. Stand alone, yes your right, but when applying it as a wash unit such as with the COP tanks (as also with dishwashers) , you have the solution recirculating in a Shell and tube or other type of heat exchanger (dish washer some sort of heating element), bring the temperature to 160-180 degrees, so that the chemicals become active. And use both chemical and ultrasonic in conjuncture with each other.

If one was to design a ultrasonic dish washer instead of using a chemical sanitiser, you would steam it to sterilize.

And to get the point across on using Ultrasonics as a dishwasher, Ultrasonic as with any one process as washer is not the answer, but a combination of processes is. As with current disherwashers.

I stand corrected. Thanks for the info.

No, its healthy to question

ultrasonic frequencies can break up cells, I don't know the frequency range or the relationship of cell size to frequency, or the effects on viruses.

-and ears. Who'd want one in their home. Not me.

What would the power consumption be relative to conventional? I suppose environmentally (since we're always on the subject) a bit more power consumption in the home might make for a lot less chemical pollution and energy required to clean up the waste water. I'd think about it then. Actually, thinking about it, wouldn't this require all the dw contents to be submerged?? Result in domestic water consumption?

Can be nominal, (which is a safe abiguous answer),

And your right about the buzz that it greates, But in a disherwasher, I would be think that can be contained in a closed unit.

I had design one the cut dairy products. And that is a big issue. There are a form of feed back ear protection out there that will cancel out the noise.

But like I said there still is development that needs to be done. Its like one has to design, develop or solve 10 more issues to make one work.

Yes they have to be totally submerged, it all depends on economics on how is currently done.

viruses ?????

It is just a matter of particle size. Ultrasonics primary mech of cleaning is cavitation and interaction with the particle. The size of the particle you are trying to remove from a surface governs the frequency you need to use.

Ex: for large > 25 um particles 48 to 64 KHz, for 10 um particles 64 KHz to 75 Khz, smaller you need to go into a 125 KHz or greater (ie megasonics). Now as frequency increases the depth of interaction decreases, thus you need to move power up as the frequency goes up to cover the same tank depth. This is very simple (grade school level).

This is very simple (grade school level).

-----

Nice, informative post - up to this point.

"This is very simple (grade school level)."

I must of been sick that day we covered that.......

So Mr. goosemydog's remark of "All it needed was cold water and a transducer." is not really correct, there is more to it if one wants to make the dishwasher perform.

And as a engineer in the business of OEM, it's not a matter of producing equipment, its a matter of producing equipment that performs.

(I had seen and worked with well educated engineers that did not understand that, as hard as it is to believe, and by not understanding they actually brought company's they worked for into nonexistance)

Thanks for the enlightenment. Sounds like it still might happen. However, if chemicals are still going to be needed, what's the point? Water pressure is a form of 'sonic' vibration, is it not? How about using different frequencies to kill the bugs? Or pass the water through a sterilizing light frequency?

It all depends on want you want removed, minerals proteins, the point is their is no magic bullet. you look at the what need to be done. An example is ultrasonics can have a more efective cleaning when there are crevices to clean. (not all the time)

The frequencies are variable. and also we do use UV to kill the bugs(bacteria). (one customer asked, then how do you get the dead bugs out)

How many do you want? I have an heated ultrasonic washer that we use to clean 316SS parts. You can put any detergent or sanitizer in the water. It's for sale at around $12,000 USD

If you are using an ultra sonic stack to be used in a vessel to clean mechanical parts, What is the best way to "power" the ultra sonic elements.

- with a sinusodial current (analoog amplifier or PWM signal) or with a square wave current?

- with a fix frequencies (20kHz and 40 kHz) or with a variable frequency (20 - 50 khz)?

- is it possible to adjust the output power by changing the amplitude of the output signal? Is the relation linear or logaritmic?

- any idea about the electrical impedance of an vibrating stack? (R, L, C)

most regards

Not quite sure I understand your meaning of a stack, Applying ultrasonics, the manufacturers are very helpful, with even an inhouse lab for trials to see hoe effective it would be,

(2) I can recall Branson Ultrasonics www.bransonultrasonics.com but checkout this web site, and find a contact. the experts would be there. They can explain the difference between wave pattern and clipped wave patterns and answer your questions.

and I believe dukane ultrasonics.

An appliance company I worked for, investigated the use of ultrasonic dishwashers. The conclusion at the time was that people will put valuable antique dishes in them. These dishes may contain micro-cracks that may cause the dish to break when exposed to ultrasonic cavitation. Based on this, the program was discontinued.

I can fully understand the worry, but the people who put valuable antiques that are not marked "Dishwasher Safe" (only non genuine antiques carry this mark!!!!!), are on their own anyway.........

Surely even a US Judge would not find for the plaintiff if the handbook and machine were clearly marked!!

micro cavitation is how it cleans and ablr to get into small areas

Good reason to discontinue. Another one (for me) is that I don`t want to see my dog putting his paws on the ears for two hours of operation.

Well, then. Don't put him in the dishwasher.

...it will make him go clean round the bend......!

We've grown rather fond of our sonic dishwasher. I particularly enjoy his rendition of Siboney.

I have seen ultrasonic cleaning used for cinematographic films (both negative & positive) and carburettor nozzles. But that was nearly 35 years ago. I don't know whether the same technic is still used