Applies to high pressure cleaners having a pressure not less than 25 bars and not more than 250 bars with an input to the drive for the high pressure pump not exceeding 10 kW. It also applies to steam cleaners having a usable volume of the water container equal to or greater than 1,5 litres even if the pressure is less than 25 bars. Also applies to fixed appliances within the limits of the previous paragraph. It is also applicable to appliances making use of other forms of energy for the motor; but it is necessary that their influence is taken into consideration.