Operation and maintenance · 4 min read · Updated 2026-09-25
Safety around an ultrasonic cleaning tank
Hot alkaline liquid, a running bath that causes pain and tissue damage to a hand put into it, noise above the hearing range that is still noise, fumes, and heavy baskets over an open tank. The hazards of an industrial cleaner, and the habits and fittings that control them.
Technical guide. Figures are taken from our own spec tables; for your process we confirm the settings with a cleaning trial.
An ultrasonic cleaner is a tank of hot chemical solution with several kilowatts of heating and ultrasound in it. It is not dangerous in the way a press or a lathe is, and that is exactly why the incidents happen: a hand in the bath "just to move a part", a basket swung over the tank by hand, a lid left off overnight in a closed room.
Never put a hand in a running bath
Cavitation does not distinguish between a part and skin. A hand in a running industrial tank feels an immediate ache in the joints and, within seconds, burning; the bubbles collapse against the skin and the bone. Tissue damage from short exposure is real and takes weeks to heal. The rule is absolute: ultrasound off before anything but a part goes into the liquid. On the AL and AU series the cycle runs with the lid closed and the basket moves on the lift, so hands stay out by design; on a single ST tank it is a habit and a sign on the machine.
Hot liquid
Baths run at 50 to 70 °C, soak stages hotter. Splashes from a basket dropped into the bath, or from the surface when the ultrasound starts in a gassy bath, are the everyday burn. Lower baskets slowly, wear gloves rated for the bath temperature and chemistry, and keep the level 50 mm below the rim.
The drain valve on an industrial tank delivers 100 to 400 litres of hot alkali; open it into a container or a drain that is meant for it, not onto the floor.
Chemistry
Alkaline degreasers at working concentration are irritant to skin and eyes; the concentrate is corrosive. Gloves and eye protection when dosing, an eyewash station within reach, and the safety data sheet of the cleaner on the wall. Never mix cleaners, and never add acid to an alkaline bath or the reverse. Acids and chlorinated products do not belong in a standard AISI 304 tank at all; see tank material.
Flammable solvents are not used in an open heated ultrasonic tank. Ultrasound aerosolises the liquid surface, the heater is an ignition source, and the room fills with vapour. Solvent cleaning is done cold, in a closed beaker in the indirect method, in a ventilated area, and only with a solvent whose data sheet permits it.
Fumes and aerosol
A hot bath evaporates several litres a day from a 200-litre tank and the ultrasound carries a fine mist of solution with it. In a small closed room that means a wet film on everything and a sore throat by lunchtime. The lid, on whenever the basket is not moving; extraction over the tank on lines that run all day; and the diamond-shaped lid on the larger series, which drains condensate back instead of dripping it on the floor.
Noise
The working frequency is above hearing, but the cavitation produces broadband noise, some of it in the 10 to 20 kHz band that younger ears hear as a piercing whine. Measured levels at an open 200-litre tank at 28 kHz are typically in the 75 to 85 dB(A) range. The lid brings that down by 10 dB or more; a lid and hearing protection for anyone working at the tank for hours is the usual answer, and the reason the AL and AU series run with the lid closed during the cycle.
Electrical
Water and several kilowatts. The generator cabinet stays dry: on the ST series it is separate from the tank for that reason. Cables routed off the floor, the machine on its own residual-current protection, and no extension leads. Any leak from the tank into the transducer compartment is a stop-and-isolate fault, not something to watch.
Handling and lifting
A basket of steel parts in a 100-litre tank weighs up to 100 kg; on the AL series up to 1000 kg. Above about 20 kg the basket is moved by hoist or lift, never carried, and never swung over the open tank by hand. The pneumatic lift on the AL series and the servo-controlled platform on the AU series exist as much for safety as for throughput. Lift areas are kept clear and the pneumatic supply is isolated for maintenance.
Fittings that make it easier
Lid or cover, level switch that stops the heater on low liquid, over-temperature cut-out, interlocked lift, stack light visible across the shop, emergency stop on the panel, drain valve with a hose connection, eyewash and gloves at the machine, and the cleaner's data sheet in a sleeve on the cabinet. Ask for the ones your machine does not have; most fit any series.
