In the Westinghouse lighting manual I have, it states that for 120 volt lamps sold here in the USA, those of 40 watts and greater are gas filled (argon/nitrogen mix), but those under 40 watts are vacuum. This is done for efficiency. Gas fill reduces filament evaporation, so the filament can be run hotter (more efficient) for the same life, but that due to larger surface-area-to-volume ratio of the thin wire needed for low wattage lamps, the heat loss due to convection and conduction to the gas more than cancels out the efficiency gain of gas fill.
For Europe (230 volts), I would expect that lamps up to 60 watts would be vacuum, and lamps of 100 watts and great would be gas filled. Or perhaps they are all gas filled to suppress Barkhausen oscillations driven by the higher power line voltage. Don Borowski Schweitzer Engineering Labs Pullman, WA, USA John Woodgate <[email protected]> wrote on 10/20/2004 09:23:03 AM: > In article <[email protected] > pqcorp.net>, Conway, Patrick R (HOU) <[email protected]> writes > > >I was thinking less of individual units that fail in the field, > >and more of the fact that simple, everyday, devices have the capability > >for significant impact. In this case a television set in an apartment > >building may interfere with the ability of a search-and-rescue team to > >reach a survivor. This is why we do what we do. > > Vacuum incandescent lamps can oscillate strongly at VHF (50 MHz and > above). It's called Barkhausen oscillation and depends on metal from the > filament being deposited on the inside of the glass envelope, to act as > an electron reflector. Works something like a klystron. > > Mains voltage vacuum lamps are rarely used these days, and the above is > one of the reasons. > -- > Regards, John Woodgate, OOO - Own Opinions Only. > The good news is that nothing is compulsory. > The bad news is that everything is prohibited. > http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk > > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/listserv/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Ron Pickard: [email protected] > Scott Douglas [email protected] > > For policy questions, send mail to: > > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
