French pressure cell press

[2] The press uses an external hydraulic pump to drive a piston within a larger cylinder that contains the liquid sample.

As the sample passes through the valve, the fluid experiences shear stress and decompression, causing cellular disruption.

The major components of a French press are made of stainless steel to prevent sample contamination.

A French press is commonly used to break the resilient plasma membrane and cell walls of bacteria and other microorganisms for isolation of proteins and other cellular components.

[3] The disruption of cells in a French press generates 'inside-out' membrane vesicles which are required for many in vitro biochemical assays.

Diagram of a French press: The arrow indicates the direction of the force exerted on the piston by a hydraulic ram. The fluid compressed by the piston is prevented from escape by a rubber O-ring at its lower end.
French press