pressure outside the bellows favours the opening of the valve and the thrust of the adjustment spring on the shutter acts in the opposite sense. Given a specific setting of the spring, the valve progressively opens in line with the increasing condensation pressure, and closes when this pressure decreases. When the compressor stops, the valve closes: water is no longer fed into the condenser, this being a notable operating economy. Valve setting is performed in the works at a pressure of 7,5 bars. Setting is modified by turning the control screw.