APPLICATIONS AND SOURCES OF ULTRAVIOLET 



81 



in all types other than F. Types C, D, E, and F have recently l)eeii 

 made commercially available, primarily for the inactivation of serums and 

 vaccines. Types A and B have been adapted to milk disinfection. 



Laboratory Methods. Useful laboratory methods for the ultraviolet 

 disinfection of absorptive liquids have been reported. Hollaender and 

 Oliphant (1946) have used a spherical fused-quartz glass flask, inclined 

 about 45° from the vertical and about one-third full of liquid, rotated 

 slowly on its axis. The film of li(iuid which was dragged up and over on 



MECHANICAL 

 AND GRAVITY 



D E F 



Fig. 2-18. Basic types of thin-film ultraviolet irradiators for relatively opaque liquids. 



the inner side of the lower two-thirds of the flask was irradiated through 

 the upper third by ultraviolet sources surrounding the flask; this pro- 

 vided a closed system but only for intermittent operation. Hollaender 

 has also suggested an inclined fused-ciuartz tube containing indentations 

 along its lower third and paralleled above by three or more tulnilar ultra- 

 violet sources which irradiate a turbulent stream of liquid through the 

 uncoated upper two-thirds of the tube. This is a closed system without 

 trouble from deposits and is adaptable to continuous pressure operation. 

 It would seem to have practical possibilities in spite of its ineflRcient use of 

 the ultraviolet sources. 



