Philips HPI (-T, -T and Plus Plus)Metal Halide lamps are lamps made of quartz discharge tube is filled with high-pressure mercury and a mixture of metal halogens a bright elongated (tubular) form. The exterior is a hard glass outer envelope of quartz glass. All have the E40 lamp base. The HPI T Candela to white.
Lamppost with three lights SON!
Advantages of HPI T lamp is a very high light output (up to 95 lumens per watt!) And very stable and good lumen maintenance that Philips HPI T lamps for outdoor lighting create a very good source.
Application of the HPI T lamp. One she sees in many public lighting such as tunnel lighting and security lighting, railway, railroad crossings, airports, harbors and docks, quarries, lampposts and petrol stations.
History and Operation HPI T lamps. The first generation lamps HPI was launched in December 1968 in Eindhoven. This lamp is representative of the earliest style of metal halide light source designed by Philips. Its arc tube is dosed with the same chemistry as the first commercial metal halide lamps, namely, the iodides of sodium (orange), thallium (green), and indium (blue) to a white light output. Heat-reflective coating of colloidal graphite is created behind the electrodes, in order to prevent a cold spot and halide vapor pressure is high to maintain this for maximum performance.
The ends of the arc tube to hold conical. This in order to keep this area as hot as possible. A disadvantage of this form is that the temperature changes with the burning position, and these variants have a great impact on the transmitted spectrum. Later HPI lamps have a cylindrical body with sharp angles for a controlled cold place for more stable performance.
Security HPI T lamp Philips HPI lamp should always be used in enclosed fixtures because the hard glass outer envelope sometimes can break at end of life! This can be dangerous when there are hot surfaces (of up to 600 degrees Celsius) can fall down. 
