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Lamp life explained
Anyone who deals in projectors would have experienced an early lamp failure versus the 2000 hours typically quoted.
So what is meant by the 2000 hours that is typically quoted? According to the bulb manufacturers the lifetime a lamp is rated at means that half of the lamps sold will exceed that lifetime in hours and half would have a brightness of more than 50 per cent of their starting brightness.
As an analogy, if four shiny new cars were advertised with a two year warranty and a top speed of 100 mph, then by lamp life measurements, the model would be deemed successful if in two years time two were still running and could achieve a top speed of 51 mph. Clearly this is a misleading method of measurement and the industry recognises that a new standard of measurement is required, particularly for the consumer market.
Why do lamps fail?
It is often the case that lamps do not actually fail, they just get old and dim. Over the course of usage, the conducting gas depletes and the pressure in the lamp falls. Additionally, the electrodes burn back and this makes the arc in the lamp longer. Because a shorter arc is better, this adversely affects the lamp's performance.
The net result of all these changes is that the light output to the screen is lowered. The change in pressure often results in a colour shift and a greenish tinge.
More catastrophic or, as one manufacturer describes it, ?non passive?, failures can occur for a number of reasons, all affecting the quartz envelope. Overheating through poor ventilation or blocked filters, mechanical shock (dropping it) and incorrect cooling - where the envelope gets stressed when the projector isn?t allowed its cooling down process - can all cause failures.
How to extend the life of your projector lamp
  Do not allow the projector to overheat.
Do not obstruct the air intake or exhaust vent.
Clean the air filter regularly (every 3 to 6 months depending on your usage and the environment).
If the projector is built into a compartment, wall, ceiling or shelf mount, the minimum distance requirement (usually at least 2 feet) stated in your owner's manual must be maintained Manufacturers can test for failure due to overheating and any warranty might become invalid.
Once you turn on your projector, wait at least five minutes before turning it off to allow the fan to properly cool the unit.
Always switch off using the remote control and not by disconnecting the power, the projector will invariably go into a cool down mode when the image is turned off and the fan accelerates to cool the lamp in a controlled manner.
Do not move your projector until the lamp has cooled (usually about five minutes, although this is shorter with some modern projectors).
If your projector is equipped with a "high/low lamp" switch you can extend your average lamp life by using the "low lamp" position whenever possible.
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