MA type automatic mixers offer a working range of 1:10, from 4”-DN 100 up to 14”-DN 350 sizes and cover the flow rates from 216 l/min up to 25300 l/min. This mixer works balancing the pressure from the water and the foaming agent in order to assure a correct mixing ratio for different water pressure values, the device adjusts instantly the mixing ratio since the two pressure values are picked up from the water line and the foaming agent line and transferred into a balancing head at the top of the device. Therefore the stem of the inside regulation valve positions itself to assure the correct quantity of foaming agent to be injected into the water line, which happens in the low pressure area of the Venturi mixer contained in the lower part. A calibrated diaphragm at the inlet of the lower body defines the nominal mix percentage. Foaming agent pressure at about 2 bars higher than the expected water pressure is required for correct functioning of the equipment.