MPUV/ MPHO lamps are much higher power than an LP germicidal lamp. Lamps start at approximately 100W/inch and go up to 700w/in. The standard MPUV mercury lamps have output peaks at 254nm and 365nm. Other applications call for other wavelengths such as 385nm and 417nm.
These additional radiation peaks are created by dosing the lamps with heavy metal compounds. The most common additives in MPUV/MPHO lamps are Gallium, Lead and Iron. The addition of metal halide salts into a standard mercury lamp alters the spectra of the lamp. When adding a metal halide to a lamp -all the wavelengths of that the metal will be produced and the mercury spectra will have its lines lowered/changed in intensity. All the materials in the arc are interactive. (The prediction intensity for specific lines in a metal halide lamps can only be stated based on the lines listed in spectroscopy manuals as "strong" lines and "persistent" lines will be more intense.)
Metal halide lamps require ballasts designed to run metal halide lamps. The starting voltage for an additive lamp is higher than for a standard mercury by several hundred volts and can vary with lamp age and number of times the lamp is ignited.
SPD's (Spectral Distribution Trace) of MPUV HID Lamps
Click on the following graphs to see an enlarged view: