Estimating swamp cooler capacity

Is there a way to estimate a swamp cooler's CFM output?
I have the cooler but no decent exhaust vent, so I need to figure out how large of one to make. I found a site that recommends 1-2 sq. ft. per 1,000 CFM, but my cooler is old and has neither rating plates nor model numbers. It's a larger whole-house cooler with a brand new 1/2 HP motor. The motor is rated at 1,725 RPM (on high) and drives a 16"x16" squirrel cage at a 1:3.5 reduction.
Thanks, -Scott
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This is Turtle.
Here is a chart for discharge air to go by to get your discharge right or close. This will be calculating a non-restrictive grill over both ends of your discharge duct or box to carry the air out.
12" X 12" hole to get 800 cubic feet per minute. 14" X 14" --------- get 1,200 --------------------------. 16" X 16" --------- get 1,500 --------------------------. 18" X 18" --------- get 2,000 --------------------------. 20" X 20" --------- get 2,400 --------------------------.
A 16" X 16" squirrel cage with a 1,725 RPM 1/2 motor is going to give you over 2,000 cubic feet per minute [ CFM ]. You really need to talk to some Swamp cooler dealers and get the right CFM before installing it with the discharge being to small or too big. Do it right the first time and not have to deal with it later.
Now you could get all the data you need from a Swamp cooler dealer if you talk to him nice.
TURTLE
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