An inlet device for separating a gas phase from a liquid phase in a fluid stream when introduced radially into a vessel, said inlet device comprising: a flow channel having an inlet end where the fluid stream enters the flow channel and outlet ends where separate portions of the fluid stream exit the flow channel, the outlet ends being spaced from the inlet end; a separation can position at each of the outlet ends of the flow channel, each of the separation cans comprising: a cylindrical wall having an inner surface and an outer surface and forming an open interior region that is open at opposite upper and lower ends; (50 and 52) an elongated inlet opening in the cylindrical wall and positioned adjacent one of the outlet ends of the flow channel to allow one of the portions of the fluid stream when it exits the outlet end of the flow channel to pass tangentially through the inlet opening in the cylindrical wall into the open interior region where it swirls within the open interior region to facilitate separation of the gas phase from the liquid phase in the fluid stream; and slots formed in the cylindrical wall to allow some of the liquid phase of the fluid stream when swirling within the open interior region to pass outwardly through the slots and exit the separation can while the separated gas phase flows upwardly and exits the separation can through the open upper end of the open interior region. a flow channel having an inlet end where the fluid stream enters the flow channel and outlet ends where separate portions of the fluid stream exit the flow channel, the outlet ends being spaced from the inlet end; a separation can position at each of the outlet ends of the flow channel, each of the separation cans comprising: a cylindrical wall having an inner surface and an outer surface and forming an open interior region that is open at opposite upper and lower ends; (50 and 52) an elongated inlet opening in the cylindrical wall and positioned adjacent one of the outlet ends of the flow channel to allow one of the portions of the fluid stream when it exits the outlet end of the flow channel to pass tangentially through the inlet opening in the cylindrical wall into the open interior region where it swirls within the open interior region to facilitate separation of the gas phase from the liquid phase in the fluid stream; and slots formed in the cylindrical wall to allow some of the liquid phase of the fluid stream when swirling within the open interior region to pass outwardly through the slots and exit the separation can while the separated gas phase flows upwardly and exits the separation can through the open upper end of the open interior region. a cylindrical wall having an inner surface and an outer surface and forming an open interior region that is open at opposite upper and lower ends; (50 and 52) an elongated inlet opening in the cylindrical wall and positioned adjacent one of the outlet ends of the flow channel to allow one of the portions of the fluid stream when it exits the outlet end of the flow channel to pass tangentially through the inlet opening in the cylindrical wall into the open interior region where it swirls within the open interior region to facilitate separation of the gas phase from the liquid phase in the fluid stream; and slots formed in the cylindrical wall to allow some of the liquid phase of the fluid stream when swirling within the open interior region to pass outwardly through the slots and exit the separation can while the separated gas phase flows upwardly and exits the separation can through the open upper end of the open interior region.