Dear Phil
I have never worked with ambulance or fire equipment so can only give an educated estimate.
The roughest usage medical devices get in hospitals is usually in the Accident & Emergency department. That's where "crash" trolleys really crash! (I once went to test a "broken" defibrillator & found a crash trolley shaped hole in a partition wall. It was just like Tom & Jerry. The staff complained the trolley "had no brakes".)
Some A & E staff believe an ECG machine is a device made for knocking a swing door open when a major trauma comes in.
Case parts can be replaced with relative ease and at reasonable cost, but I've found that in general items can only be expected to last about 8 years in the A & E environment before the accumulated punishment begins to take a toll on the internals of machines and then it all becomes very expensive.
Consequently I would expect ambulance & fire service equipment to last about 6 years before it becomes a liability.
In military applications the standard of equipment build is on an entirely different level and stuff is expected to get thrown, splattered with mud, cooked & frozen.
Unfortunately despite their ridiculous cost and critical application medical devices are generally far too lightly built for longterm reliable transport / roadside use.
Marc
