AS 2773:2019 Ultrasonic cleaners for health service organisations
3.20  Ultrasonic generators
Ultrasonic generators shall conform to the following:
(a) Located to protect from ingress of dust and moisture.
(b) Accessible and removable multipin plugs and coaxial connectors for servicing and adjustment.
(c) Protection of multipin plugs and coaxial connectors from ingress of dust and moisture.
(d) Automatic adjustment of output frequency by a feedback device or other means to cause optimum cavitation and implosion (see 1.4.1) of the water in the cleaning tank, under every condition of loading and water level.
3.21  Ultrasonic transducers
Ultrasonic transducers shall conform to the following:
(a) Construct and attach so the transducer will not loosen during service.
(b) Consist of piezoelectric type or magnetostrictive type.
(c) Consist of crystals that —
(i) are bonded to the tanks; and
(ii) have an average life during normal use of not less than 3 000 h.
(d) Operate at an ultrasonic frequency of not less than 20 kHz.
(e) Produce electrical power at the transducer terminals of not less than 5 W/L.
NOTE 1  A greater power may be required to achieve the performance requirements of Clause 6.2.In order to be able to calculate the ultrasonic input to the tank, the efficiency of the transducer should be known.
(f) Operate at a power level not greater than the manufacturer’s rated capacity.
NOTE 2  Forced air cooling or perforated panels (to allow natural ventilation) may be required to prevent overheating of the transducers.
3.23  Temperature indicators
Where heating units are fitted, a temperature indicator shall be provided to indicate the temperature of the cleaning solution in the cleaning tank. The sensing point of the temperature indicator shall be located in the tank where it will not be unduly affected by radiant heat from the heating units or the ultrasonic transducers. The temperature indicator shall be as follows:
(a) Have a response time to change of temperature at the operating temperature of not more than 10 s.
(b) Be accurate to within ±2 °C (see Note 2).
(c) All dial type temperature indicators shall operate at their midrange.
(d) Display the temperature in a clearly legible manner as follows:
(i) All dial type temperature indicators shall have a size of not less than 38 mm.
(ii) Temperature indicator displays shall be legible from a distance of 1 m.
(iii) Height of characters on digital displays shall be not less than 5 mm.
NOTE 1  Legibility is affected by the type, the size and the position.