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INFRARED DRYING OVEN I. K. HENKE University of Wisconsin, Madison, Wisconsin
Tm drying of organic chemistry laboratory prepara-
dealer. The lamps are arranged (see illustration) to provide uniform illumination of the oven floor. The metal screen shelf (I/,- X '/,in. mesh galvanized wire screen is used), on which samples are placed, is raised above the bottom of the oven by 2-in. furring strips. In this way a more effective circulation of air is obtained. A supporting framework for the oven may conveniently be made from standard 1-in. pipe and fittings when table mace is not available. The com~leted oven assembly is painted with a mixture of 1 p a r t b ~ y p tal No. 1202 (G.E.), 2 of thinner No. 1500, and 3 of aluminum bronzing powder. This mixture spreads ~vell,is not too readily absorbed by the transite surface, and does not turn yellow from heat. It also gives a pleasing finish.
tions and other materials by the use of infrared electric lamps rather than by the convection type of oven has been found over a period of eight years to be very satisfactory. The use of the infrared lamp as an oven unit for this purpose was suggested to the author by James T. Watson of St. Louis, Missouri. Through the usual evolutionary process the design shown in the illustrations was developed.
Drying O v a n Closed
The oven frame is constructed of 1- X 1-in. angle iron melded into a cube of inside dimensions 24 X 24 X 24 in. The walls are made of 1/4-inch transite; holes ca 2 in. in diameter in the sides (2 each) and top (5) produce an entirely adequate circulation of air through the oven interior. (Forced-air circulation has been tried with these ovens: it was found that the drying capacity mas not increased appreciably thereby.) The front door of the oven is of the drop-panel type, fastened by a friction catch, and held in a horizontal position, when open, by short lengths of chain. The open door thus serves as a shelf to hold samples which are being placed into, or removed from, the oven. The door does not extent the full height of the oven in order to protect the lamps. Four type-PS 30 clear, 120-volt, medium base nonilluminant infrared drying lamps provide adequate heating a t a power consumption of 1000 watts. These lamps can he obtained through any General Electric
Drying oeen Open
Continued use of this type of oven during a period of eight years has failed to reveal any serious defect in it. Eight are now in use in the organic chemistry lahoratory here, where, it is estimated by Prof. Michael W.
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Klein, they afford a saving in time of up to 50 per cent over the conventional type oven in this application. This increased efficiencyhas been particularly valuable in view of the greatly increased enrollment in the laboratory courses in recent years.
ACKNOWLEDGMENT
The author wishes to thank Mr. Robert Holliday, of Milwaukee, Wisconsin, for his assistance in the early developmental work on the infrared drying oven.
