Magnetic Drive for Spinning-Band Column. N. G. Foster and L. E. Green, h.',ResearchDepartment, Standard Oil Co. (Indiana), m i t i n g , Ind.
I
ISTILLATION columns employing a spinning hand as packing Dhave become popular since 1938, when LesesneandLachte (3) first announced their column. Many investigations have shown the outstanding characteristics of spinning-band columns to be low pressure drop, low operating holdup, and high efficiency. These features apply also under vacuum operation, but vacuum seals are difficult to maintain with laboratory equipment incarparating moving parts. Such a seal on spinning-band columns operated continuously for 100 hours or more st pressures below 1.0 mm. presents a problem in equipment design. Available designs ( I , d , 4 ) are inadequate for these severe service conditions. To eliminate the need for a drive shaft passing through a stuffingbox type of vaouum seal, a magnetic drive permitting isolation of the column for pressure control has been devised and experimentally applied in this laboratory to commercially available semimicrospinning-band columns. This equipment is shown in Figure 1 and detailed in Figure 2.
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Thevseuum-tight brass housing for the loner magnet and connecting shaft is clamped in position to allow free rotation of the drive shaft and is connected to the partial condenser of the column by means of heavwvalled
BEARING SPACER-mass
consider a b l y removed
no difficulty. 1he UDDW magnet el&s the brass housing by '/,sineh. Two d r o n s of a l o w - v a n o r ab the predsure oil hearing lubricant. The housing threads %resealed with a resin varnish.
Magnetic drives of this type have been operated e x p e r i m e n t a l l y in this Figure 1. Assembled l a b o r a t o r y f a r several Magnetic Drive years. Continuous distillations of 120 hours have been made, and constant absolute pressures as low as 0.1 mm. have been maintained. The magnetic clutch, which ordinarily operates a t 1500 to 2000 r.p.m., does not lose speed or uncouple even when viscous samples are being distilled. The magnet is normally accelerated from a &art to full speed in 10 to 15 seconds. Bearing life has been excellent and has averaged shout 6 months. This simple, inexpensive, and easily accessible seal has permitted full utiliaatian of spinning-hand column^ operated under vacuum.
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rigure E.
111
Uetail Of IVlaCnetlc Unve
(2) Cruthirds, A. V., Jon
48,No.41. 117-19 (3) Lesesne, S. D., and Loohte, H. L.. IND.ENG.C ~ E MANAL. ,, ED., .n
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(4) Murrc~y,K. E., J . Am. Oil Cfiaists' Soc., 28,235 (1951).
Machine for Determining Packed Density. D. M. Peppard, Research and Development Division, Wyandotte Chemicals Gorp., Wyandotte, Mieh. who manufacture, ship, or handle flaked, powdered T or granular materials are often concerned with the packed, density of these materials. I n order to save time and improve HOSE
(1) Birch, S. F., Grim, V., and Nathan. W. S.. J . SOC.Chem. Id.. 66,3340 (1947).
1 Preaent
address. Btanollnd Oil and Gas Co.. TEdsa, Okla
the accuracy of packed density measurements i t is desirable to perform the tedious tapping operation mechanically. Packed density is the weight per unit volume of a material 1869
