361: 



THE INDIA RUBBER WORLD 



[August i, 1906. 



VACUUM DRYING AND IMI'REGNATING APPARATUS. 

 [As made by the J. P. Devinc Co. (Bullalo, New Votkl. under American Rights srante.l to them by the lirni oi Emil Passbuig, Berlin ] 



or have to be treated with very heavy compounds. It must 

 not be understood that the drying under vacuum and im- 

 pregnation under vacuum and afterwards under higher 

 pressure must necessarily take place in the same vessel. The 

 drying under vacuum may take place in one vessel and the 

 impregnation in a second one. When removing the male- 

 rial from the vacuum dryer into the vacuum impregnator. it 

 is necessary to break the vacuum in the former vessel and 

 allow the atmospheric air to enter it and naturally the pores 

 of the insulating material. .\s this air only fills such pores 

 once and can only once deposit the moisture it carries, such 

 moisture will have no detrimental effect whatever, as in the 

 first place it has no circulation and but little enters anyway, 

 as such. In addition to this, as soon as the material is 

 placed in the vacuum impregnating vessel, the latter, which 

 can be fitted with heating coils, etc., is evacuated and the 

 material is not only at once freed from the atmospheric air, 

 hut also from any particle of moisture which it could possi- 

 bly have absorbed during this short interval. This is only 

 mentioned so as to dispel any doubts as to the impractica- 

 bility of using two in.stead of one ves.sel for drying and 

 impregnating. 



As in many cases solvents of a volatile nature are used 

 with compounds for impregnation for the above described 

 purposes and as the drying and impregnation process takes 

 place under vacuum and as consequently if with such 

 vacuum impregnation and drying vessels, vacuum pumps 



and suitable condensers, are connected, any volatile sol- 

 vents, apart from the water which naturally is being re- 

 moved during the first drying process, and before the im- 

 pregnation process, can be regained in such condensers 

 during the second drying. 



The whole resolves itself, therefore, into three processes: 

 (t) to dry under vacuum ; (2) impregnation under vacuum, 

 with the assistance of the outer atmospheric pressure ; and 



(3) to increase this impregnation by artificial pressure in ad- 

 dition to the atmospheric, of which the advantages as com- 

 pared with the former processes have been above described ; 



(4) to furtlier the recovery of all valuable solvents. 



Onic of the minor uses of India-rubber which in the aggre- 

 gate has become important is in connection with carpet 

 sweepers. The amount required for a single sweeper is not 

 large, but on the whole the rubber required runs into nnany 

 tons annually. Each sweeper has four wheels, and each 

 wheel has a rubber tire. Besides this, the mechanism of the 

 sweeper is operated by means of a small rubber belt connect- 

 ing with each axle. When it is remembered that the Bissell 

 Carpet Sweeper Co. (Grand Rapids, Michigan) alone turn 

 out 7000, or more than 2,000,000 a year, the importance of 

 this industry to the rubber trade can be easily appreciated. 

 The rubber bands used are manufactured especially for this 

 concern b^' one of the largest nibber concerns in the United 

 States. 



