Ultrasonic cleaning is safe when the equipment is used correctly, but the process introduces specific hazards that need to be understood and controlled. Here we cover four of the most important.
Most ultrasonic injuries are not dramatic. They are a burn, a numb finger, or hearing that is a little worse than last year. All four of the hazards below are controllable, and none of the controls are expensive.
This is the one people get wrong most often, usually while "just checking" a part. Two things are happening in a running bath at once. The solution is typically held at 50–70 °C, which is enough to scald. And cavitation — the implosion of microscopic bubbles that does the cleaning — does not distinguish between contamination and skin. Prolonged exposure can cause pain, irritation and damage to soft tissue, and the effect is worst at the tank base where intensity is highest.
An ultrasonic tank runs above the range you can hear — but the tank walls, the basket and the parts all radiate audible subharmonics, and lower-frequency machines (25 kHz especially) are noticeably louder than 40 kHz units. A large industrial tank in a hard-walled room is a genuine noise exposure, particularly for someone working beside it all shift.
Three controls, in order of effectiveness: keep the lid on (it is the single biggest reduction and it also cuts evaporation and heat loss), site the machine away from workstations or enclose it, and issue hearing protection where the first two are not enough. If you are unsure whether you have a problem, a noise assessment against the Australian workplace exposure standard is inexpensive and settles it.
Working baths sit at temperatures that burn, and ultrasonics keep adding energy — a bath left running with the heater off will still climb. Splash and aerosol matter too: a running tank throws a fine mist of whatever chemistry is in it.
An ultrasonic cleaner is a high-power electrical device sitting in a wet area — the two things that should never meet. Give the machine its own circuit rather than sharing with compressors or sterilisers; shared circuits are a common cause of nuisance tripping and generator failure. Keep the outlet and the plug out of splash range. Portable equipment in Australian workplaces is subject to routine inspection and testing under AS/NZS 3760 — ultrasonic cleaners are exactly the sort of wet-area equipment that regime exists for.
Never run a tank dry or near-empty. The transducers are cooled and loaded by the liquid; without it they overheat and delaminate, and the heater will destroy itself. Keep the bath at the fill line. Most warranty claims we see for dead transducers trace back to a tank run down over a shift and never topped up.
Every machine we commission is handed over with the operating procedure written for the parts you actually clean, including the safety controls above. If you have inherited a machine with no procedure, we can write one.
We assess each application. Where required, we validate the process through a controlled cleaning trial on the machine and chemistry we would specify, with the cycle and the result reported against your standard — ask us to scope it.