Re: Need a proximitiy sensor only detect liquid not foam! Any suggestions? Recommendations?

On Sun, 04 Oct 2009 22:17:10 -0400, ehsjr <ehsjr@xxxxxxxxxxxxxxxxx>
wrote:

krw wrote:
On Sun, 04 Oct 2009 16:31:02 -0400, ehsjr <ehsjr@xxxxxxxxxxxxxxxxx>
wrote:


Jim Thompson wrote:

On Wed, 30 Sep 2009 18:20:14 -0700 (PDT), osr@xxxxxxxxxx wrote:



The ones I've seen on videos of breweries are air jets, they look for
the reflected pressure as the bottle fills up, and gets rid of that
annoying foam. Some pop nitrogen into the bottle at the same time.

Steve


Brings to mind an idea long-simmering in my head... measuring the sump
level in my salt-water aquarium.

Problems:

Salt water

Salt "mist"

Continual waves due to splashing skimmer filter

BUT:

I only need a low/high indication, but fail-safe sensing and
valving... water on the great room floor is not an option ;-)

...Jim Thompson

Run I/R beams, one for low level, one for high, through the
aquarium to detectors on the opposite side, blocking the beams
with an I/R opaque float in a clear tube inserted in the tank.


How about measuring the refraction similarly?

I don't know. To do that, I would think you'd need lenses to
get a narrow emitted beamwidth, and would want a known angle of
incidence other than 90 degrees. Then you'd have to move the
detector around to the maximum response point. I'm not sure how
you could do it with a fixed detector/emitter pair and a movable
float. Maybe Phil Hobbs will chime in.

A lens on the receiver should work to pick up the LED. I was thinking
of the refractive index difference between water and air, looking
through the side of the tank. Waves would create an error but I'd
think it much like that a float would give. It should average and
even be useful for a fine measurement.
.

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