sitelights
07-19-2001, 03:16 PM
I am indebted to Jeff Werbock for the following information which came as a personal email; I am posting for him verbatim.
The original socket for bi-pin lamps was a metal cage with a lever pin to dislodge the lamp from the socket, which was slotted, and the pins slid lengthwise into the contacts. Now that the bi-pins are forced into the contacts head on, there are considerable problems. They were solved by two companies, Contrast in Canada, and Translite in California. Contrast makes their own sockets (excellent), but will not sell them to other manufacturers, and Translite has 24 carat gold plated pin sockets set into an aluminum bussbar. Great heat sink. Very costly.
Lamps are tested in base up position, in open air. Lamps are used inside of housings which trap heat, and in architectural lighting applications, are most often pointing down, which increases heat to lamp base, shortening lamp life. Lamp base is sensitive to heat, and overheating will increase the differential of thermal expansion of the quartz glass versus the metal alloy strips that deliver electricity to the filament support wires. This condition increases the outgassing of the halogen gases, reducing the condition that enables the tungsten to recycle.
Fixtures designed to operate multiple lamps also contribute to reduction in lamp life for the same reasons. All things being equal, heat is the most important factor in determining lamp life. It is likely that a 37 watt I.R. lamp rated at 4000 hours will last longer than a 50 watt lamp rated at 6000 hours, enclosed in a fixture housing, especially if pointed down, or even worse, if used in a fixture that positions two or more lamps in close proximity. jw
The original socket for bi-pin lamps was a metal cage with a lever pin to dislodge the lamp from the socket, which was slotted, and the pins slid lengthwise into the contacts. Now that the bi-pins are forced into the contacts head on, there are considerable problems. They were solved by two companies, Contrast in Canada, and Translite in California. Contrast makes their own sockets (excellent), but will not sell them to other manufacturers, and Translite has 24 carat gold plated pin sockets set into an aluminum bussbar. Great heat sink. Very costly.
Lamps are tested in base up position, in open air. Lamps are used inside of housings which trap heat, and in architectural lighting applications, are most often pointing down, which increases heat to lamp base, shortening lamp life. Lamp base is sensitive to heat, and overheating will increase the differential of thermal expansion of the quartz glass versus the metal alloy strips that deliver electricity to the filament support wires. This condition increases the outgassing of the halogen gases, reducing the condition that enables the tungsten to recycle.
Fixtures designed to operate multiple lamps also contribute to reduction in lamp life for the same reasons. All things being equal, heat is the most important factor in determining lamp life. It is likely that a 37 watt I.R. lamp rated at 4000 hours will last longer than a 50 watt lamp rated at 6000 hours, enclosed in a fixture housing, especially if pointed down, or even worse, if used in a fixture that positions two or more lamps in close proximity. jw