[Rob]

John mentioned that the phosphors in fluorescent lamps are toxic.
Although true the hazard is not what it once was. Since I believe sometime in the 40's or 50's the use of berillium oxide (BeO) as an additive to the phosphor in fluorescent tubes has been discontinued. It was also added to the phosphor in early B&W projection CRT's to allow the phosphor to take more punishment from beam bombardment without burning. I know for a fact that the 5AZP4 is a tube containing such a berillium oxide mixture phosphor! Other types of the same era such as the 5TP4, 3NP4 and TP-400, and 7NP4 and 7WP4 if you can find one, may be equally hazardous. Berillium oxide is one of the most carcinogenic substances known. If trace amounts of the dust are inhaled cancer can result. One manual for a video projector I once owned that used the 5AZP4 warned that in the case of a CRT implosion during operation, the cooling fan in the projection head should be disabled by shutting off the power immediately so as to reduce the spread of the phosphor dust, and the room, or theater should be evacuated immediately!

Extra care should therefore be exercised in the handling and disposal of such projection CRT's beyond the concerns merely for flying glass.

Projection CRT's are usually operated at 27KV and higher, 40 kV on the 5AZP4. This makes these tubes good X-ray generators as well. All lead shields should be in place when servicing these projectors. I owned and serviced events projectors that operated a 6" CRT at 50 kV. The big 7NP4's ran on 80 kV. A half hour exposure to this tube without shielding was lethal.

Rob