Abstract: The invention provides a valve (100) comprising, a housing (61) having ant enclosed internal cavity (66), an aperture (68) formed in a wall of the housing providing communication with the enclosed internal cavity, a valve scat (72) surrounding the aperture, an expandable valve member (40) mounted within the housing the expandable valve member having a hollow interior surrounded by a side wall of the expandable valve member, the side wall and hollow interior extending through a portion of the internal cavity clear of the housing where it terminates in an end wall (50), and a port (67) communicating with the hollow interior, wherein the construction and mounting of the expandable valve member and housing re such that the internal cavity of the housing may be evacuated to provide a region of sub-atmospheric pressure around the expandable valve member whereby the application of air pressure greater than sub-atmospheric pressure through the port can act to expand the expandable valve member to bring the end wall (

Abstract: A milk meter suitable for measuring a quantity of milk flowing through the meter including: a sealed holding chamber (1); entry means (3) for admitting liquid to be measured into the holding chamber; a foam bypass chamber (3); sensing means (5, 7a) for sensing when milk is at or above a predetermined level in said foam bypass chamber, an inlet (13b) arranged to allow communication of milk between the holding chamber and the bypass chamber, the inlet being provided at a level below the predetermined level; drainage means (4, 8) associated with a timer, the drainage means being arranged to allow the milk to drain from the holding chamber for a set period of time (t) in response to a signal from the sensing means; and measuring means (11) arranged to count the number of times (n), milk has been drained from the holding chamber and to display the milk volume and/or flow rate.