At 02:39 14-07-98 +0100, ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
--snip--
I believe something like this does exist. A Kennedy
winchester service
manual mentions a plugged hole on the HDA cover as being a port for a
particle counter which you use to tell you when to change the breather
filter.
This port allows one to check performance of the HEPA filter in the air
moving system.
I don't know how it works. For high particle counts
(like your vacuum
cleaner), I would guess you could use light scattering. I can't believe
that would work at class 100 levels, though.
Light scattering is how most particle counters work and indeed they are
sensitive in the range below class 10.
--Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA
Member of Antique Wireless Association
URL:
http://www.ggw.org/freenet/a/awa/