Now THAT is out of the bag thinking! Brilliant.
73, Jeff ACØC
www.ac0c.com
-----Original Message-----
From: Jim Barber
Sent: Wednesday, April 13, 2011 3:14 PM
To: AMPS
Subject: [Amps] Bag-o-meter calcs in US units
Not to run it into the ground, but does this look right?
(in US units)
. Construct a duct of heavy paper to match/mate the air output duct on
the amplifier, tape it to a US-standard 33-gallon trash bag
. Flatten the bag to eliminate as much trapped air as possible
. Fire up the amp and allow the blower to come up to speed
. Stuff the paper duct onto the amplifier output duct (get as good a
seal as possible) and simultaneously start the watch
. Stop the watch at the point where the bag is fully inflated
So assuming it took roughly 2.5 seconds to inflate the 33-gallon bag:
(1) 33 gallons * 0.13368 = 4.414 cubic feet
(2) 2.5 seconds / 60 = .0417 minutes
(3) 4.414 / .0417 = (is roughly equal to) 106 cubic feet per minute (CFM)
Seems like the very short inflation time would reduce the practical
accuracy of the measurement for larger amplifiers, but you could
certainly get a rough number. Very useful.
73,
Jim N7CXI
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