Our unique expertise and experience in submerged blowers started with the development of the submerged circulator concept. This was carried forward into the development of the Advanced Gas-cooled Reactor power stations in the UK, where we supplied upwards of one hundred 6MW circulators over a twenty year period. These circulators were designed for both horizontal and vertical arrangement. They operate submerged in CO2 at 4 bar pressure, with oil bath or pressure fed bearings, and gas flow control by variable inlet guide vanes. The later units including external pressurized lubricating oil system, were seismically qualified.