14 A
ANALYTICAL
CHEMISTRY
TODD VACUUM PRESSURE REGULATOR UNITED STATES PATENT NO. 2,419,042 This combination vacuum pressure regulator and leak indicator is recommended for many laboratory vacuum operations where sensitivity, stability, and ease of precise pressure control are essential. PHYSICAL CHARACTERISTICS Using mercury in regulator Range: 2 to 50 mm. Hg. Sensitivity: i 0.05 mm. Hg. (a.v.) Using butyl phthalate in regulator Range: 0 to 4 mm. Hg. Sensitivity: 10.01 mm. Hg. (a.v.)
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FEATURES \
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STABLE PRESSURE CONTROL is maintained even in systems which have moderate leaks. RESPONDS RAPIDLY to any pressure changes in a system.
^ OPERATION OF THE R E G U L A T O R T h e vertical control screw, S, o n t h e regulator is simply screwed u p or d o w n u n t i l a n y desired pressure, as m e a s u r e d o n a m a n o m e t e r or o t h e r g a u g e , is obtained. T h e control screw, S, varies t h e liquid h e a d , h , by t i l t i n g t h e regulator t h r o u g h any angle from vertical w i t h m a x i m u m pressure to horizontal w i t h zero pressure. T h e stopcock (shown i n photograph) is u s e d o n l y w h e n t h e regulator is started or stopped, or for by-passing t h e regulator w h e n it is n o t n e e d e d . Air leakage or vapor formation i n a v a c u u m s y s t e m are indicated by t h e r a t e a t w h i c h t h e s e gases b u b b l e u n d e r t h e liquid i n t h e regulator.
For additional
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VERSATILE DESIGN enables either mercury or butyl phthalate to be used in the regulator depending on the range and sensitivity of pressure control desired. NO M O V I N G MECHANICAL PARTS during operation to cause fouling, loss of sensitivity, or wear.
HIGH MECHANICAL ADVANTAGE (average approx. 100) of the control knob readily permits fine and positive adjustment of the regulator.
NO ACCESSORIES REQUIRED for the operation of this sturdy, compact regulator. SIMPLE OPERATION makes this regulator especially useful for vacuum distillation, sublimations, extractions, pyrolyses, and many other vacuum operations in chemical, physical, and biological laboratories.
TODD VACUUM PRESSURE REGULATOR s h o w n above h a s a n operating range u p t o 50 m m . of mercury. T h e Pyrex brand glass part is 6" h i g h and t h e overall h e i g h t of t h e regulator is 10". T h e c o m p a c t and sturdy m e t a l h o u s i n g , w h i c h supports t h e glass part, is finished w i t h a corrosion res i s t a n t baked-on black e n a m e l . This regulator is supplied w i t h t h e horiz o n t a l support rod a n d operating instructions but without the mercury, or b u t y l p h t h a l a t e $24
details, see article, "New Design of Vacuum Pressure Regulator," Analytical Chemistry, Dec, 1948. Write NOW for free reprint.
by F. Todd,
TODD SCIENTIFIC COMPANY Designers and manufacturers of special scientific laboratory apparatus.
SPRINGFIELD, PA.
