Accession Number : AD0451427


Title :   DIFFUSION PUMP BAFFLE STUDY


Corporate Author : NRC EQUIPMENT CORP NEWTON HIGHLANDS MA


Personal Author(s) : Hablanian, M H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/451427.pdf


Report Date : Nov 1964


Pagination or Media Count : 76


Abstract : This study was undertaken to develop and test a diffusion pumping station having maximum pumping speed consistent with minimum backstreaming for use on a large space environmental chamber. The complete system includes pump, duct, and baffle. Conductance measurements were made using small-scale model ducts and baffles to determine the most promising configuration for the full- scale system. As a result of this preliminary work, a 52 inch diameter liquid nitrogen cooled baffle was developed which has a transmission probability of 0. 35 while the reducer duct-baffle combination developed retains 50% of the pumping speed above the baffle. Backstreaming measurements ranged from 7.3 x 10 to the -7th power mg/sq cm-min for a short duration test (63 hours) to 7 x 10 to the -8th power mg/sq cm-min for a long duration test (524 hours). Along with the backstreaming measurements, the residual gas composition in the test dome was checked with a mass spectrometer residual gas analyzer. A lesser aspect of this study was to compare the backstreaming rates of two diffusion pump oils above a liquid nitrogen cooled baffle. The baffle was constructed to approximate the full-scale 52 inch baffle.


Descriptors :   *DIFFUSION PUMPS , COLLECTING METHODS , CONDUCTIVITY , COOLING , CURRENTS , DUCTS , GASES , HEAT TRANSFER , MEASUREMENT , NITROGEN , OILS , ORIFICES , PRESSURE , STRUCTURES , WEIGHT


Subject Categories : Pumps, Filters, Pipes, Tubing, Fittings & Vlvs


Distribution Statement : APPROVED FOR PUBLIC RELEASE