Keep track of your video projector lamp hours

If you're like me, you work at a school that dipped its toes in the pool of video projectors over 10 years ago when they were 500 lumens each and cost $4000-$5000. Over the years, more and more departments found the money to purchase projectors, mounts, and cabling. Projectors slowly increased in resolution and brightness, all the while decreasing in price to the point where I can now pick up a 2700-lumen XGA projector for under $650.

Many teachers jumped on the bandwagon and used their projectors often, while other projectors were rarely used. I could go an entire school year without having to purchase a projector lamp.

However, as we go into the 2010-2011 school year, nearly every classroom in my school of 3300 students has a video projector. And with it, many teachers are using their projectors all periods of the day. Most of the projectors eventually lose brightness to the point where they are no longer usable, but a seemingly suprising amount of lamps are actually popping in the middle of usage. (Maybe 5 or more a year?)

In order to properly plan for how many projector lamps we'll need to purchase (beg for funds) each year, my department started carefully tracking the lamp hours of every projector in circulation. For the past 18 months, we periodically visited every projector on the same day, cleaned the filter, and took note of the lamp hours.

We started during Spring Break 2009. Using data from Spring Break to Summer Break 2009, we tallied 13,778 lamp hours over 52 school days. Extrapolating this to a 176-day school year, we were on pace to total 46,633 annual lamp hours. I initially divided the annual hours by 2000 hours, the average expected life of most projector lamps. This means we needed to purchase at least 23 lamps each year.

We tallied lamp hours again during Winter Break 2009 and Summer Break 2010. Now that we have over a year's worth of data, we can concentrate on just Summer Break 2009 and Summer Break 2010, and no longer have to extrapolate. We totalled 50,766 hours, so we are on pace to need to stock over 25 lamps per year. We installed a few more projectors this summer, so I expect that number to continue to rise.

So, for the near future, we can bank on needing at least 25 lamps per year. At an average of $300 per lamp, this works out to $7500 per year. However, for budgeting reasons, I know these numbers will be skewed by a couple of factors:

1. Since we neglected to plan for lamps for so many years, we let many projectors go past the 2000 hour mark, and many more are approaching the 2000 hour mark. I'm calling this the Projector Lamp Baby Boom phenomenon. We figure for the next year or two we may need more than the average number of lamps per year.
2. In some cases it makes sense to purchase a new projector because the old projector may be too dim even with a new lamp, or has too low of resolution, or replacement lamps are too expensive.
3. Most of the new projectors I purchase have an expected lamp life of 3000 hours, so I'll eventually need to refine my calculations.

I used a simple spreadsheet (currently in Google Docs) to keep track of the lamp hours. You'll need to create a new column each time you take a lamp hour measurement. You'll also need to be careful of how you keep track of projectors whose lamps you replace. For example, for my Summer 2010 measurements, I actually have 2 columns. I put the same data in both columns, unless I wind up changing a lamp over the summer. This way my previous and future lamp usages will be more accurate.

Happy tallying!