AVS 46th International Symposium
    Vacuum Technology Division Wednesday Sessions
       Session VT-WeA

Invited Paper VT-WeA7
Dry Pumping

Wednesday, October 27, 1999, 4:00 pm, Room 610

Session: Dry Pumping Systems
Presenter: P. Annandale, Alcatel Vacuum Products
Authors: S. Doherty, Alcatel Vacuum Products
F. Ramberg, Alcatel Vacuum Products
P. Annandale, Alcatel Vacuum Products
Correspondent: Click to Email
There are many reasons to convert from oil sealed, or so called 'wet,' vacuum pumping systems to those where no seal fluid or lubricant is exposed to the process gas. Among these are contamination, cost, and environmental impact. With certain deposition processes this conversion presents problems related to the phase change of the material pumped and its effect upon the pump and its handling by subsequent abatement systems. Alcatel has studied and characterized several processes that presented extremely difficult challenges in the conversion from wet to dry pumping. These conversions were ultimately successful due to an understanding of material properties and reactions possible within the pump and system hardware and the correct management of pump design and application. Alcatel will present process analysis, design features, and operating data that demonstrate how such classically difficult processes may be converted from wet pumping to dry pump systems. The analysis will include phase diagrams of the materials and products of reaction for the process, conductance calculations for the piping system, and the pumping speed requirements. A survey of dry-pump design types demonstrates why the process is difficult to achieve; and an in-depth discussion of the successful design is included. Finally, the data that demonstrate not only successful pump operation but, an accounting of process material is presented. What may be concluded from the presentation is what analysis techniques are available to determine whether a process will be difficult to convert from wet to dry pumping, and methods to predict what dry pump design type will yield success. Further, we will show the relative increase in reacted and reactive material exhausted from a dry pump over that from a wet system.