"Phisherman" wrote in message

I took a 22-year old fire extinguisher to the local fire department
and they told me it was still good as long as the dial indicator
pointed to the green region. It is a good idea to have one near
every exterior door, one in the garage, and one in each vehicle.

Seems as thought he seal u nits for home use are exempt from testing or any
time limit. Here are the OSHA rules,

http://www.osha.gov/pls/oshaweb/owad...ARDS&p_id=9811
The employer shall assure that portable fire extinguishers are subjected
to an annual maintenance check. Stored pressure extinguishers do not require
an internal examination. The employer shall record the annual maintenance
date and retain this record for one year after the last entry or the life of
the shell, whichever is less. The record shall be available to the Assistant
Secretary upon request.
1910.157(e)(4)
The employer shall assure that stored pressure dry chemical extinguishers
that require a 12-year hydrostatic test are emptied and subjected to
applicable maintenance procedures every 6 years. Dry chemical extinguishers
having non-refillable disposable containers are exempt from this
requirement. When recharging or hydrostatic testing is performed, the 6-year
requirement begins from that date.