The mechanical seal of the Sulzer A pump with R-650 metal bellows is designed for use at temperatures from -20 to +425°C, with pressures up to 2.5 MPa and rotational speeds up to 15 m/s. It is independent of the direction of shaft rotation, unloaded, with sealing secondary elements made of flexible graphite. Designed for operation at ultra-high temperatures and viscous, aggressive media (hot hydrocarbons, aqueous solutions, crude oil fractionation products, heat transfer fluids, alkalis, acids, mineral fertilisers).