CHAPTER 2 



Practical Applications and Sources 

 of Ultraviolet Energy 



L. J. BUTTOLPH 



General Electric Company, Lamp Division, Cleveland, Ohio 



Inlroduclion. Germicidal-aclion curves: Action curve tentative at shorter wave lengths- 

 Action curve approximate at longer wave lengths—The unique 2537 .4 mercury line 

 Susceptibility to ultraviolet: Injury, mutation, and kill—Comparison of susceptibility to 

 ultraviolet and to other lethal agents-Logarithmic nature of kill— Unit kill— Reactivation 

 by heat and light— Germicidal action of ultraviolet of wave lengths greater than 2800 A— 

 Composite of killing factors. Killing exposures: Reciprocity of time and intensity. 

 Erythemal action of wave lengths 2537 and 2967 A: American Medical Association 

 tolerance— Face and eye protection and treatment. Commercial sources of ultraviolet- 

 High- and low-pressure mercury arcs— Ultraviolet of wave length 2537 A— Conversion 

 factors— Intensity— Ozone formation— Photochemical effects of 2537 and 1849 A energy- 

 Temperature and ventilation— Depreciation. Ultraviolet disinfection: Air disinfection— 

 f luid disinfection- Disinfection of surfaces of granular materials. Ultraviolet-induced 

 m utantsfor new fungi. Protection and processing of products: Mold, antibiotics, and par- 

 enteral fluids-Blood plasma— Syrup, fruit-juice, and wine storage— Meat storage 

 Higher pressure mercury sources of ultraviolet: Intensity and variations with distance- 

 Individual line intensities-Starting and restarting times-Life and depreciation- 

 Research determination of output and intensity— Mercury-amalgam and other metal 

 arcs — S unlamps. References. 



INTRODUCTION 



Innumerable applications of ultraviolet energy are suggested in a volu- 

 minous amount of old literature, in which there is little of practical value 

 because of the failure to specify the ultraviolet wave lengths, the inten- 

 sities, and the exposure times used. This is equally true of the many 

 chemical, the indefinite therapeutic, and the few biological effects of the 

 ultraviolet. Ellis et al. (1941) have comprehensively reviewed the 

 chemical and biological applications of the ultraviolet; Laurens (1933) 

 has done the same for the physiological effects. Meyer and Seitz (1949) 

 and Roller (1952) have excellently reviewed the sources, measurement, 

 and various applications of the ultraviolet. Lea (1946) has contrasted 

 the excitation effects of ultraviolet with the ionization effects of X ray and 

 shorter wave length radiations in a practical discussion of the theoretical 

 bjises of both effects, 



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