A multi-way valve comprises a pressure equalisation piston (30) which can be actuated by magnets (70) and which can close off different flow paths (14,15,16). A bellows unit seals two chambers (20,21) along the piston. Both ends of the bellows have assembly members (81,82) contg. static sealing elements. The bellows is fixed to the valve piston and seat via a coupling or screw connection.The bellows pref. consists of PTFE. Use - The arrangement is used as a multi-way valve. Advantage - The bellows is simple to attach and remove for eg maintenance.
