[Bloat] [Starlink] [Rpm] On FiWi

rjmcmahon rjmcmahon at rjmcmahon.com
Sat Mar 18 14:18:25 EDT 2023

>> I'm curious as to why the detectors have to be replaced every 10
>> years.
> Dust, grease from cooking oil vapors, insects, mold, etc. accumulate,
> and it's so expensive to clean those little sensors, and there is so
> much liability associated with them, that it's cheaper to replace the
> head every 10 years. Electrolytic capacitors have a limited lifetime
> and that is also a good reason to replace the device.
> The basic sensor architecture is photoelectric, the older ones used an
> americium pelllet that detected gas ionization which was changed by
> the presence of smoke. The half-life on the americium ones is at least
> 400 years (there is more than one isotope, that's the shortest-life
> one).

Thanks for this. That makes sense. I do think the FiWi transceivers & 
sensors need to be pluggable & detect failures, particularly early on 
due to infant mortality.

"Infant mortality is a special equipment failure mode that shows the 
probability of failure being highest when the equipment is first 
started, but reduces as time goes on. Eventually, the probability of 
failure levels off after time."


Also curious about thermal imaging inside a building - what sensor tech 
to use and at what cost? The Bronx fire occurred because poor people in 
public housing don't have access to electric heat pumps & used a space 
heater instead. It's very sad we as a society do this, i.e. make sure 
rich people can drive Teslas with heat pumps but only provide the worst 
type of heating to children from families that aren't so fortunate.


"A malfunctioning electric space heater in a bedroom was the source of 
an apartment building fire Sunday in the Bronx that killed 17 people, 
including 8 children, making it one of the worst fires in the city’s 
history, New York Mayor Eric Adams said Monday."


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