how to degas your ultrasonic cleaner

Why Degas Your Ultrasonic?

Before the start of each working day it is best to degas the liquid in your ultrasonic cleaner tank.  This simple procedure allows the ultrasonic cleaner to work most effectively, since the ultrasonic waves can pass more freely through liquid than they do when air is mixed in the liquid in the tank.  If you are in a lab, or a dental, vet or medical practice this is the ideal time to prepare for your daily foil test.

You should also perform this task whenever you start with a fresh tank of water during the working day.  NB Take extra care when you empty your ultrasonic cleaner tank, as this is a risky time – see notes below.

Unless you are in a laboratory or clinical setting, where you will be completing a foil test to meet regulatory obligations, you can use the degas process to start your daily cleaning.  The first 10 minutes of degas/cleaning will be a little less effective than the rest of the day, but they will still generate a very good cleaning result.  Anyway, you’re paying for the electricity – you may as well get some value out of it.

How to Do It

  1. Fill the tank with the recommended amount of water and add a squirt of dishwashing detergent.  The detergent will help to soften the water which assists in the degas process.
  2. Degas the water in the tank.  Set heater thermostat to 60C.  After temperature is achieved run unit on cleaning cycle for about 10 minutes.  Degasing will expel the air so that the unit operates at optimum effectiveness.
    • NB If your machine does not have a heater, or if the heater is slow to increase temperature, you can boil water in a kettle to get the same result.  In a boil proof jug add two parts boiling water  to one part tap water.  If the tap water is room temperature (25C), the combined water will give you about 60C.  Adjust the mix for local conditions.


  1. Foil Test. Always degas the tank before doing a foil test.
  2. Many desktop machines are designed to maintain minimum set temperature with their heater, but they can be rather slow to heat up, especially if ambient (or tap water) temperature is low. You can run the machine (e.g. start to clean some items) while the unit is heating.  This will usually only draw a small amount of additional electricity, but it will save time and help to get the tank up to operating temperature a lot quicker.  Covering the tank with its lid will also help speed the process.
  3. Empty Tank Safely. Some hints to safely empty liquid from your ultrasonic cleaner’s tank, for units without a tap.
    1. Water and Electricity Do Not Mix. Turn off power and disconnect unit from mains before emptying tank. Refill tank when unit back in designated safe working location and before power is reconnected to machine.  Remove all spills promptly and completely, ensuring that no water is on or near leads, plugs or power points.  Do not turn power back on until it is safe to do so.
    2. Cool Tank to 25C. Wait until liquid inside tank has cooled before emptying – you should turn heater off, or set thermostat to zero C and empty liquid only when contents has dropped to room temperature.  This will prevent damage to heater pad.
    3. Check for Lost Stones.  If you have been cleaning jewellery check that no stones have not come adrift from settings BEFORE you empty the tank. This problem is more common than you might think.  If you discover a setting is minus a stone use our procedure to find it in the tank, or ensure that you pass liquid through a fine sieve. Do not just pour liquid down the drain.
    4. Avoid Splashbacks.  Most ultrasonic cleaners are very well sealed around the top and sides of the unit.  But bench top ultrasonic cleaners will commonly have holes in the base or rear to allow for venting of excess heat from the unit.  So it is possible for liquid to enter the unit when tank is being emptied.  You would be amazed at where splashed water can end up. We recommend against vigorously upturning the unit to empty the tank, as this can cause unwanted liquid splash backs or internal components becoming dislodged.   Instead, use a household plastic jug to bail the liquid out (also makes it easier to use a sieve if searching for missing stones) and to wipe out the last bit of liquid in the tank with a clean sponge.  This procedure takes no more than a few seconds, but it can save a lot of time and money.

Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)

Best Frequency for an Ultrasonic Cleaner

We’ve often been asked ‘what is the best frequency?’ for a customer who is in the market for an ultrasonic cleaner.

Like many things in life, there is no simple black and white answer.  It’s like asking a vehicle salesman whether it’s better to buy a truck or a car.  Both will get you from A to B, but the best solution depends on the individual’s situation.  For instance, a furniture removalist will find a truck more useful, whereas a real estate agent would definitely find a car more appropriate – especially when it comes to parking in busy shopping centres!


Early ultrasonic cleaners tended to be in the low frequency range – roughly 15 – 25 kHz.  Their wave patterns meant that they were very good at ‘blasting’ heavy contamination off metallic objects with plane surfaces.  But, they were not very good at cleaning items with fine detail (such as apertures, threads and blind holes), nor did they give consistent cleaning results across a surface, unless the object was moved about inside the tank during the cycle.  Lower frequencies were also found to have an impact on softer materials being cleaned.

More modern cleaners tend to deliver frequencies in the upper range – between 40 – 45 kHz.  The wave pattern of these cleaners results in a more gentle and more thorough cleaning result, so they usually have no effect, even on softer metals.  Often there is no need to adjust an item’s placement in the ultrasonic tank to ensure all surfaces are properly cleaned, which means a faster result with less labour. The higher frequency wave pattern also has a better cleaning effect on parts with fine detail (eg the apertures, threads and blind holes that the lower frequency cleaners do not clean well).  However, the trade-off is that higher frequency cleaners will not always have enough ‘grunt’ to remove the heaviest contamination, so it will take longer to properly clean some items, or the machine will need to be more powerful, or some additive will be needed – in some cases all three!

Cleaning requirements, materials and situations vary.  So, operators cannot always get by with a single frequency solution.  In summary:

Low Frequencies – ‘blast’ effect, especially for plane surfaces, but can be hit and miss unless object is adjusted inside tank, and poor for fine detail.  Not good for softer materials.

High Frequencies – gentle consistent cleaning across a variety of surfaces and good for fine detail. Suitable for even soft metals. Not ideal for heavy contamination.

The Solution – Dual Frequency Control

So, how can we overcome the shortfalls of low and high frequency wave patterns in ultrasonic cleaning?

Not every heavily contaminated item has a plane surface.  Often these parts are designed with flanges, apertures and threads to connect to other parts.  Sometimes these items are weighty, and are awkward to adjust inside the tank.  For other items, such as surgical instruments, patient care and infection control policy dictates that instruments need to be perfectly clean, before moving on to the sterilisation procedure.

Dual frequency ultrasonic cleaners combine the advantages of the high and low frequency wave patterns in a single unit.  They significantly reduce capital cost and the footprint required to accommodate the equipment.  ‘Space’ was the final frontier for Startrek, but the lack of it is equally important in today’s clinic or workshop facility.  The better designs feature options to switch between high and low frequencies and to select a range of power settings.  This provides substantially greater control over the cleaning environment than less sophisticated machines, and ultimately leads to a better cleaning outcome.

Dual frequency ultrasonic cleaners allow the operator to clean items in a multi stage process, that minimises cleaning time, staff intervention and the need for additives.

As a general rule, dual frequency ultrasonic cleaning will be conducted as follows:

Stage 1. Use the low frequency ultrasonic cleaner setting to dislodge gross matter and heavy contamination.  Unless material is soft or delicate, use full power and complete a 30 minute cycle.  Remove basket from tank and examine objects.  If heavy contamination remains, repeat process – NB Removal of basket and examination of objects will adjust position of cleaning object – aiding in cleaning consistency.

Stage 2. Use high frequency ultrasonic cleaner setting to address fine detail cleaning and to ensure cleaning result is thorough across all surfaces.  Set for additional 30 minutes cleaning cycle and examine object to ensure desired result is achieved.

Note: For surgical instruments, refer to practice procedure manual and ensure that at start of day tank is degassed and unit’s working condition confirmed, using the foil test.

Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)

Testing Your Ultrasonic Works

Not sure that your ultrasonic is working properly?

The foil test is one test that can tell you if  it is.

Foil Test

The foil test is commonly used in medical, vet and dental practices, before the start of each day.  It is critical that surgical instruments are properly cleaned, then sterilised.  A properly functioning ultrasonic cleaner is the key to an effective cleaning process.


  1. Fill the tank with the recommended amount of water and add a squirt of dishwashing detergent.  Detergent will help to soften the water.
  2. Degas the water in the tank.  Set heater thermostat to 60C.  After temperature is achieved run unit on cleaning cycle for about 10 minutes.  Degassing will expel the air so that the unit operates at optimum level.
    • NB If your machine does not have a heater you can boil water in a kettle to get the same result.  In a boil proof jug add two parts boiling water  to one part tap water.  If the tap water is room temperature (25C), the combined water will give you about 60C.  Adjust the mix for your local conditions.

Test Procedure

You will need a piece of kitchen aluminium foil large enough to cross the tank diagonally and to drop towards (but not quite to) the bottom of the tank, with some excess foil above the water, that you can hold onto.   The foil should be oriented vertically (ie hanging downwards) – if it is laid horizontal the test will be invalid. NB Do not allow body parts to touch or be immersed in the tank water at any time during cleaning operation.

passed foil test

Typical Result – 90 seconds in 100W Ultrasonic Cleaner

Run ultrasonic cleaner through a 10 minute cycle, while holding the foil above the water line, with the foil descending to just above the bottom of the tank, and hanging diagonally across the tank.

Remove and inspect foil.  A functioning ultrasonic cleaner will show evidence of the cavitation effect on the foil.  The more powerful the machine the more intense the reaction.  This may range from pin sized indentations in a light weight machine of say 30W, to foil being ripped to shreds in a larger unit (say 100W+).  Lack of indentations is a sure sign that machine is not working properly.  If you performed this test after delivery from the supplier you should advise the supplier and request return/replacement instructions.

Warning:  Some cheaper machines are named in a way that will deliberately mislead the buyer.  Unless the machine clearly states that it is an ultrasonic cleaner  customers should assume that it is not.   Ultrasonic cleaning pretenders will never pass the foil test.  Contact the supplier or your local Department of Fair Trading for further advice.

NB If you are in a medical/dental practice consult your practice manager or your practice procedure manual. Medical practices in Australia should refer to AGPAL if they need specific guidance.

Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)

Setting Up Your Ultrasonic Cleaner

OK.  You’ve bought your new ultrasonic cleaner and you want to know how to set it up.  There’s a trick to doing most things – and this is no exception.  A little time spent following a procedure could save you a lot of money!

Protecting Your Investment

Inspect the box for damage before opening it.  If outside shows any sign of rough treatment during transport, take photos – they might be needed to show the supplier or freight company for a claim.

  1. Take more photos of the unit and anything inside the box if they have been damaged in transit.  Take a clear image of the unit’s serial number.
  2. Inspect contents. Take particular note of the tax invoice and the unit’s user manual/operations guide.  Often the items supplied will be specified in the user manual.  Check you have them all.  If not, contact the supplier ASAP and ask for anything that seems to be missing.
  3. Tax Invoice  A valid tax invoice will show GST included in the sale, the supplier’s Australian Business Number (ABN) and address in Australia.  The tax invoice is a valuable document which should be kept safe and produced (or copied) if you ever have any warranty issues.   Some sellers on Ebay will provide a tax invoice which is generated through their system.  As long as the document meets the requirements set out in the New Tax System (GST legislation) it doesn’t matter what it looks like.  This contrasts with invoices/shipping documents that make no mention of the words tax invoice, GST included in the purchase and the supplier’s ABN.  We recommend caution if dealing with a supplier who ships cleaners without a valid tax invoice, because it is extremely unlikely that you are dealing with a registered Australian business who can be forced to adhere to Australian consumer protection laws.

Product Safety and Compliance

Once you know you have everything that’s supposed to be included, you can move on further.  The next step is about checking your unit is safe for you and your staff.

  1. Check the power lead provided with the unit has an approved Australian/New Zealand style plug – sometimes suppliers will provide one that fits in the socket, but it does not have the insulation on the top pins (normally black).  Plugs without visible insulation on the top two pins are the ‘old style’ which ceased being approved for sale in the late 1990s.
  2. Check for C Tick label.  Electrical equipment needs a C Tick label to identify the authorised supplier and to show that the supplier can prove the device meets Australian/NZ EMC requirements.  By law ALL ultrasonic cleaners sold in Australia and New Zealand must have this label, whether imported or manufactured locally.  They also require the supplier’s electrical code (usually a number starting with letter N or V, representing the state the company is registered in).   NB If the unit does not have a C Tick and the supplier’s electrical code, then it is illegal for sale in Australia and New Zealand and it may also be unsafe.  Contact your local Department of Fair Trading and request a refund from the supplier.
  3. Check power supply.  Most quality units will be manufactured for 240Volt mains supply.   Many units will state 220 or 230 Volts, or some range between these.  The closer to 240 Volts the better.   If the unit is labelled less than 220 Volts its working life can be much less than one made for 240.  NB Do NOT attempt to use a device made for US power supply (110 Volts).  Return it f or replacement or refund.
  4. Use a surge protector. Even robust commercial ultrasonic cleaners can fail due to power surges.  Like computers, these days, ultrasonic cleaners all have electronic components which can easily burn out when power spikes occur.  We recommend taking sensible precautions, like using a quality surge protector at all times and to remove the device from the power outlet during electrical storms,  or when you are absent from the workplace..

User/Operating Manual

Most suppliers will provide a user or operating manual.  Manuals from quality suppliers units will be in plain English that the average person can understand.  Often the manual will also specify the unit’s warranty and support arrangements.   We recommend against items that must be sent overseas for warranty service.  The following points are obvious, but we’ve all seen the line – if all else fails read the manual.

  1. BEFORE you connect the unit to the power supply, or attempting to use it ensure that you read the manual and understand it.
  2. Follow the instructions in the manual.  If you don’t, often the manufacturer’s warranty will not apply.  It could be an expensive mistake.

Next Step

After you have set up your machine as per supplier’s user manual, you should immediately test its function.   Run a simple foil test to satisfy yourself you have a true ultrasonic cleaner, not a dud.  If the machine fails the test contact the supplier and have it replaced/get a credit.


  1. EMC is Electro Magnetic Compatibility. When a product shows the C Tick symbol it tells the consumer that the supplier has proven that the device meets the Australian/New Zealand regulations for EMC.  A product that does not meet EMC rules may interfere with radio and other communications, including devices such as pace makers and other sensitive life saving equipment.
  2. The supplier’s code (usually a number starting with letter N or V) on an electrical product tells the consumer that the supplier has tested the device for compliance with the Australian/New Zealand regulations for electrical safety.  The CE label often seen on electrical products has not value in Australian/NZ.  It is easily confused with an almost identical CE label which represents Chinese Export.
Liquid Glass Oz designs quality ultrasonic cleaners for commercial operations in Australia and New Zealand (N18973)