[compost_tea] measuring true air output under water.

From: Robert Norsen <bnbrew_at_yahoo.com>
Date: Sun, 25 Jan 2004 23:25:50 -0800 (PST)

Some months ago there was a rash of concern about true air volume. It seems many air pumps did not put put out the volume they were rated at. Others put out more when the actual air was measured at the outlet. For large air system an air flow meter could be used. For small pumps the air flow meter is rather approximate and most of us don't own one. So I measured the air carefully collected in a light weight plastic bag for an exact time, like 1 minute. fit the loosely fillled bag in a box where rectangular dimensions permitted actually measuring the volume. Easy enough. 10 minute test. .
 
How to do this under 3 feet of water? Cold water ? Brrrr ! Do this:
 
Same thing in reverse. Inflate a bag to a known volume, bag measured in a box. Secure the air carefully with a tube that will fit the INLET of your pump. Get the pump going long enough to reach equalibrium. That is, all the water of the air system blown out so the system is operating as it will. Then introduce the tube to the INLET with no air leaking in around the inlet. Measure the exact time it takes to deflate the bag. Convert that to CFM Note this does not measure your air pump. It measures your entire aeration system. If your pump puts out more than your system even when out of the water or in very shallow water, maybe the holes in your aeration system need to be increased. However expect a decrease in air flow as the release level in water gets deeper, Bob 01 25 04
                                   No snorkle No bikkini . Ruined your fun??




Received on Mon Jan 26 2004 - 11:52:05 EST

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