110 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1957 



Cleaning 



Schedules were established for cleaning the areas at regular intervals, 

 the frequency and methods depending upon the type of manufacturing 

 operations and the activity. Usually, the vinyl plastic floors were ma- 

 chine scrubbed and vacuum dried. Walls, windows and ceilings were 

 cleaned by hand with lint-free cloths. Manufacturing facilities such as 

 bench tops, which were linoleum covered, were washed daily. Test sets, 

 cabinets, test chambers and bench fixtures W'Cre also cleaned daily. 

 Hand tools were cleaned at least once a week by scrubbing with a solu- 

 tion of green soap, rinsing in distilled water, followed by alcohol and 

 then dried in an oven. 



Dust Cou7it 



Since it was impossible to determine what contaminating material 

 in the form of air-borne particles might be encountered from day to day, 

 and what the effect might be during the life of the repeaters, the general 

 approach to this problem was to control, so far as possible, the amount 

 of dust within the plant. 



In order to verify, continuously, the over-all effectiveness of the vari- 

 ous preventive measures, dust counts were made in each classified area 

 at daily intervals, using a Bausch and Lomb Dust Counter. This device 

 combines, in one instrument, air-sampling means and a particle-counting 

 microscope. Over a two-year period it has been possible to maintain, in 

 certain areas, a maximum dust count of between 2,000 and 3,500 particles 

 per cubic foot of air with a maximum size of 10 microns. Control checks, 

 taken outside the building at the employees' entrance, generally run 

 upwards of 25,000 particles per cubic foot, a good portion of which are 

 of comparatively large size. 



PRODUCTION AND PERSONNEL 



Equipping the plant, obtaining and installing facilities, and selecting 

 and training personnel proceeded on a closely overlapped basis with 

 receipt and analysis of Bell Telephone Laboratories' product design 

 information. Because of the critical nature of the product, provisions 

 were made not only for the most reliable commercially available utilities 

 and services, but also for emergency lighting service in some areas. 

 Maintenance and service staffs had to be built up rapidly as the super- 

 visory and manufacturing forces were being developed. 



