Apparatus for determining the deviation in the level of liquid in a vessel

Apparatus for determining the deviation in the level of liquid in a vessel from a desired level corresponding to a preset volume, the apparatus comprising a vessel for collecting liquid, the vessel having a narrowed neck portion with a neck cross-sectional area, a displacement means insertable into the narrowed neck portion of the vessel to temporarily reduce the neck cross-sectional area and displace a portion of the liquid in the vessel over a weir means, and measuring means for receiving the liquid displaced over the weir means to determine the deviation in the volume of liquid in the vessel from a preset volume;

• wherein the displacement means comprises:
• an elongate member which is inserted into the vessel to displace the level of liquid in the vessel upwardly over the weir means;
• and
• a hollow tubular member which is closed at the lower end thereof, said tubular member having an inlet defining the weir means over which the displaced liquid flows on insertion of the tubular member.