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AUTOMATIC SAFETY TRAP FOR LABORATORY STEAM DISTILLATIONS EDWARD M. HUBBARD Monsanto Chemical Co., Dayton, Ohio
THE automatic safety trap for laboratory steam distillations described by Nickels' has several advantages. Water and oil are removed from the steam and automatically drained, suck-backs caused by decreases in steam pressure are prevented, and excess pressure is released through the water seal. However, a surge in steam pressure will frequently force all of the water out of the water seal, even when the height of this seal is made twice that previously described. When the water is lost from the seal, steam also escapes and does not pass through thedistillation flask. Then water is blown out as rapidly as it condenses and does not accumulate in the seal. A shutNICKELS, J. E., 3. CHEM.EDUC.,26, 533 (1949).
Front view of Head
CHEC* VALVE
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down is then required to add water t o the seal. This distinct disadvantage requires considerable attention and time. An automatic safety trap was designed which overcomes this difficulty and has all of the advantages of the Nickels trap. Water, oil, and solids are removed from the steam and led through the water seal to the drain automaticallv. Suck-backs are orevented bv air entering the vent and passing throughathe check-valve. Excess pressure is released through the water seal. During tests, while steam was admitted through a wideopen valve in the 10 p. s. i. laboratory steam line, the steam exit tube from the trap was suddenly closed. The excess pressure was relieved through the water seal, yet after several minutes the seal still retained the normal amount of water, and the apparatus returned to normal steam delivery immediately when the steam exit tube was reonened. The trap will supply steam to several steam distillations simultaneously through Y-tubes in the trap exit line. Each distillation can be started or stopped individually without interrupting the others. The height. of the water seal can be made in accordance with the load to be carried. Spherical joints are placed on the steam lines to reduce danger of the trap's being broken when rubber tubing is changed. Grease is not needed on the joints. 376
