Vacuum system, design conductance

The overall recommendation for the roller compaction system design that minimizes bypass is to employ a higher surface roughness or textured surface on the rolls, rolls oriented similar to vi or vii, and to conduct an assessment of vacuum deaeration. 

Differential pumping is the term used to describe the process by which different pressures are maintained in various locations within the instrument, e.g., during the desolvation of ESI droplets and in the collision-induced dissociation cells used in MS/MS instruments. As dictated by the requirements for differential pumping, vacuum systems are designed as a series of interconnecting chambers with low conductance connections, between which ions can be moved efficiently, while the pressures necessary for the operation of the individual components are preserved. Typically, pressures of -10 to 10 Torr ( 10 ° Torr in FT instruments) are required in mass analyzers. 

Strobel, M. L., Strobel, C. J., and Delin, G. N., 1998, Design for a Packer/Vacuum Slug Test System for Estimating Hydraulic Conductivity in Wells with LNAPLs, Casing Leaks, or Water Tables Intersecting the Screens GroundWater Monitoring Remediation, Fall, pp. 77-80. 

The equipment feed design consisted of a funnel-shaped powder hopper (with no vacuum deaeration system) that was located directly above the rolls. The powder hopper was retrofitted with vacuum deaeration capability. A high compression feed screw, fitted inside the funnel hopper, fed the powder directly into knurled rolls. The compaction trials were conducted with and without vacuum deaeration. The compact was carefully collected directly on a 10-mesh screen. Powder particles, that were not compacted (i.e., those particles which were not attached to the compact, for example, fines bypassing roll compaction and the non-adhering compacted powder particles) were weighed and separated. The compact was not milled. The parameters are noted in Table 4. 

In late April 1994, one additional monitor well (MW-9) was installed in an attempt to define the southern boundary of the contaminant plume. The consultant also conducted a pilot test to determine the design parameters for an SVE system (INTERA/BAI 1994b). The pilot test was done using 50 inches water column (we) vacuum, resulting in a well flow rate of 3 cubic feet per minute (cfm) and extracted vapor concentrations of less than 1,000 parts per million volume (ppmv). The radius of influence (ROI) suggested by the test results ranged from about 6.8 to 8.6 feet, which would result in an extraction well spacing of 10 to 15 feet. 

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