Hi Bob:
I don't recall any specific requirement in either IEC 65 or UL 1418 that the type of glass being used in CRTs as "non-shatterable" type. All CRTs must be provided with implosion protection. There are several schemes. Probably the dominant one today is pure strength. All CRTs are subjected to several tests to determine the adequacy of the implosion protection schemes. These are spelled out in UL 1418 and IEC 65 (which ARE the world's principle CRT implosion protection standards). Most CRTs break (i.e., crack and go to air), but don't implode when subjected to the various implosion protection tests. Depending on the particular test, and if an implosion occurs as a result of the test, there are limits for the size and distance of glass particles ejected upon implosion. My impression is that the checklist is addressing window glass and similar applications. It is doubt- ful that a CRT could be made of such glass due to the application. CRT glass has two major considerations, one being strength against atmospheric pressure, and the other being x-radiation attenuation. It might even be more dangerous to use "non-shatterable" glass. If the glass were to break into chunks as does automobile glass, then the differential pressure across the chunk (due to the vacuum on one side and air pressure on the other side at the moment of breakage) could give the chunk a terrific acceleration and thereby cause injury to nearby persons by high-energy chunk bombardment (kind of like a shotgun blast but with much larger shot). Regards, Rich ------------------------------------------------------------- Richard Nute Quality Department Hewlett-Packard Company Product Regulations Group San Diego Division (SDD) Tel : 619 655 3329 16399 West Bernardo Drive FAX : 619 655 4979 San Diego, California 92127 e-mail: [email protected] -------------------------------------------------------------
