Vacuum valves are an essential component in any vacuum system. There are a variety of different types that fall into three main categories – operational valves, closing valves, and sealing valves. The selection of the proper valve type requires an understanding of the process application so that the proper design and/or functioning valve can be chosen for a given vacuum furnace operation.
When talking about vacuum valves the ones that most people think of are those installed in lines that connect a vacuum chamber to a vacuum pump: the roughing valve (aka main valve if a diffusion pump package is not installed), the poppet (aka main) valve, the foreline valve, and the holding valve.
What is a vacuum valve? A vacuum valve is a device placed in a feed or vent line on a vacuum furnace whose purpose is to isolate the vacuum chamber or direct the flow of gas into the vacuum vessel. These valves can be actuated manually, pneumatically, electropneumatically, electrically or electromagnetically. A series of pressure switches are also installed in most lines with vacuum valves (other than manual valves) to control the flow and changing the internal furnace pressure as demanded by the process being run.