Click here to download this complete technical brief in PDF format.
In a typical freeze-drying production process, it is desirable to be able to isolate the freeze-drying chamber from the external condenser. Isolating the external condenser allows it to be defrosted while loading or unloading the product chamber. It also allows for loading the chamber with the shelves "cold" while the external condenser remains at ambient and for separate leak testing of the chamber and the external condenser. Traditionally, freeze dryer manufacturers have installed one of two major types of valves in the vapor line to accomplish this: a butterfly valve or a poppet valve. As shall be seen, each valve has its own particular advantages and disadvantages.
Hull Company, however, has developed a unique patented valve called the "Rotary Disk Valve." The Rotary Disk Valve combines advantages of both the poppet and butterfly valves while doing away with the disadvantages. In order to understand how this valve works as well as its features, it will be helpful to first examine the basic operations and properties of both poppet and butterfly valves.
SP Scientific Products