On Fri, Sep 4, 2009 at 8:25 PM, Chuck Guzis<cclist at sydex.com> wrote:
While we're on the subject--is there a different
rating system for
commercial applications? ?Most consumer upright vacuums boast 10-12
amp motors, whatever that means. ?After experiencing the dubious joy
of owning several consumer vacs in about as many years, I bought a
commercial vacuum, rated for hotel use. ?This by comparison, has a 6
amp motor, yet it does a job that's at least as good as my last 10
amp consumer model. ?The motors don't seem to be very different in
size, though the commercial one is ball-bearing and metal-housed and
has a brand that I recognize.
As far as I know, there's no special rating for commercial
applications. It's hard to fake an amp rating though. It either
draws that much power or it doesn't. Of course, a space heater draws
quite a lot of current and isn't a very good vacuum cleaner.
Amps is actually a better measure of power consumption under these
circumstances I think. Having said that, number of amps drawn says
nothing about efficiency. The design of the vacuum and the filter
makes a big difference. Just consider all those air filter after
market upgrades for cars that actually increase power output. There's
a whole area of nerd-speak covering things like cubic feet per minute
of air moved or static pressure at some amount of mercury or whatever.
In woodworking for example, dust collectors and shop vacuums are very
different things with different usages. For a larger tool, you want a
dust collector which would move a lot of air at a relatively slower
speed. But for a smaller tool like a power palm sander, you'd wand a
shop vac, lower amounts of air at higher speeds.
Right now, cyclone dust collectors are all the rage. They have
filters for only the very finest of dust, like 1 micron or so. The
rest is fed through a specially shaped chamber that spins the air and
uses centrifugal force to separate out the sawdust. It hits the sides
of the container and falls into a barrel below. They have a version
for shop vacs now. Have a look at this:
http://www.dustdeputy.com/
I haven't bought it yet, but it's on the shopping list. They say over
99% of the dust is trapped in the bucket and I believe it. I'm
planning to combine this with the big ridgid shopvac I'm using now.
This reminds me of the old IHF "Music Power"
ratings for audio gear
of many years past. ?Pure stuff and nonsense.
I used to be into car stereo a number of years back. They have the
same sorts of problems. Speakers and amps supposed to be rated in
watts RMS power handling or output. That's root-mean-square which is
an averaging technique. Then others started rating their products in
peak power output or power handling. Of course there's a huge
difference between a bass drum hitting that peak power number for a
split second, and the sustained bass from a rap boom truck. Then you
have to consider the amount of noise or distortion produced at a given
power output. Then there's power output for a given impedance rating
for the load. Some amp manufacturers were rating their amps with
power output numbers into 1 ohm when their amps were marginally 1 ohm
stable. In other words, they'd overheat in seconds. I'm not sure
what they're up to these days.
For woodworking, there's this "nominal" crap. 3/4" plywood is sold as
3/4" "nominal" plywood. It's really 1/32" thinner. That may not
sound like much, but it's the difference between a tight fit or not,
and having tools that exactly match the plywood thickness or not. And
they're all off a little depending on who made the plywood. Is it
really so hard to measure it out to 3/4"? I'd be willing to pay for
the extra wood. :-/
Then there's the thing about what's really a megabyte. Or P-ratings
for microprocessor clock speeds. Or 17" monitors with a 16" "viewable
area", or more recently, 46" "class" flat screen TVs.
I view it all as lying. Either lying by omission or an attempt to
hide the truth in technical details that they know most people aren't
going to know or understand. I hate marketing. Knowledge is the only
defense. But quite a lot of people are dumb or otherwise smart and
just don't have the time to learn about all this stuff. So they keep
on doing it.
brian