MMD > Archives > January 1996 > 1996.01.20 > 02Prev  Next


Bleed flow rates
By John Rhodes, forwarded by Robbie Rhodes

In a quick experiment, John Rhodes gathered this data on the air flow through a bleed:

> I fabricated a bleed from .007" brass shim stock soldered to
> the end of a short (1-inch) length of 1/4-inch copper tubing,
> then I _carefully_ drilled a hole with a #75 drill (.021-inch
> diameter nominal). The hole appears to have minimal burr, is
> quite round, and is not more than .001" oversize. All of these
> dimensions will be verified later with an optical
> comparator and microscope. I was careful not to thicken the
> brass stock with the solder, but this too must be verified
> later. (I'll peel off the shim stock from the tubing to
> examine both sides of the bleed.)
>
> Then I measured the time required to displace approximately
> 280 milliliters of water with 5, 10, 20, 30 inches-of-water
> differential-pressure across the bleed. Results:
>
> differential time
> (inches H2O) (sec)
>
> 5 42
> 10 30
> 20 20
> 30 16
>
> These numbers are crude, because I was supplying the pressure
> by blowing on the hose. (Try sustaining 50 inches for 15 seconds;
> you'll turn bright red!)

Has anyone performed this type of experiment? Anyone have some similar data for comparison?

-- Robbie Rhodes


(Message sent Sat 20 Jan 1996, 05:41:42 GMT, from time zone GMT-0800.)

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