VACUUM Strictly speaking, a space in which the total pressure is less than atmospheric. VACUUM CONTROL (Gas Bleed) To assist in the rate of sublimation, by controlling the pressure in the lyophilizer. VACUUM PUMP A mechanical way of reducing the pressure in a vessel below atmospheric pressure to where sublimation can occur. There are three types of pumps, rotary vane, rotary piston and mechanical booster. VAPOR BAFFLE A target shaped object placed in the condenser to direct vapor flow and to promote an even distribution of condensate. VACUUM VALVES The vacuum valves used are of a ball or disk type that can seal without leaking. The balI types are used for services to the chamber and condenser. They are also used for drains and isolation applications. The disk types are used in the vacuum line system and are connected to the vacuum pump, chamber and condenser. VAPOR VALVE (See Main Vacuum Valve) The vacuum valve between the chamber and external condenser. When this valve is closed the chamber is isolated from the external condenser. Also known as the main vapor valve. VIAL A small glass bottle with a flat bottom, short neck and flat flange designed for stoppering.
VIRTUAL LEAK In the vacuum system a virtual leak is the passage of gas into the chamber from a source that is located internally in the chamber.
