Bellows pump for metering small amounts - has bellows under constant external pressure and actuated by double-acting stepped piston

摘要

The arrangement is intended for metering small amounts of liquid. It comprises a metal bellows (1) with inlet and outlet via a connector (4,5) at one end, whilst the other end is secured (25,7) to a steplessly movable piston (12,15). The bellows and piston are contained in a cylindrical housing (8,16) with a connection (26,27) for intermittently admitting pressure below the piston and a connection (28) for a constant pressure. The piston is a double-acting stepped (12,15) piston whose smaller-diameter (D2) portion (12) is fixed to the lower end of the bellows and hasthe same diameter as the interior diameter (D1) of the bellows. The connection (28) is arranged at the upper end of the housing.