[aprssig] water level gauge for APRS

Steve Noskowicz noskosteve at yahoo.com
Mon Oct 5 01:18:55 EDT 2015

Some  idea fodder   in addition to the other things mentined,:

A lot depends on just how much level change you consider to be a "flood".

Floats are pretty simple.  Every auto gas tank has (had) one inside, I think.

 A sealed pipe is used in homes to eliminate the hydrolic hammering.  These need periodic flushing because gasses disolve in the water and the level goes up with the constant pressure against the decreasing amount of gas. When they fill, no more bumper.
 If the 'flood gage' is usually empty, then no problem...

I don't know if this gives anyone ideas, but...

A friend has a very clever commercial fuel tank guage in his boat.  I had the web page for it, but not now...
A tube in the tank goes to the bottom, but is open on the bottom.
A hand pump pumps air into the tube.
An analog, barometer-style mechanical pressure guage (just like on a BP cuff) on the pump shows the pressure at the pump and, therefore,  top of the tube.
When the tube bubbles out the bottom, the pressure stops building and you read the depth.  The guage is calibrated for the liquid.  I did the calculations for water and compared my results with the pressure guage on my sphygmomanometer (BP cuff)
Pretty slick.  
Paper describing in more detail

I found my calculations, but no indication of the specific company...
The conversion:
mm Hg	                  Inch Hg	                  mmH2O	                  Inches H20
1.868320156	0.073555912	25.39999984	1.0

I played with this measurement as well as a U-Tube Manometer....  The slanted version can give much more low pressure variation for an ultrasonic sensor. 

U-Tube manometer calculations:
Be careful with the Engineering Toolbox.  I found a few places where it is a little sloppy in its stuff..
These don't have the disolved gas problem.

There is a USGS guage station at the inlet of Wonder Lake that measures water height, rain and other things.  I have no idea how it works.  Next time I see the guy servicing it, I'll ask more.

Regards, Steve Noskowicz
Science & Technical Advisor

On Sun, 10/4/15, Robert Bruninga via aprssig <aprssig at tapr.org> wrote:

 Subject: [aprssig] water level gauge for APRS
 To: "TAPR APRS Mailing List" <aprssig at tapr.org>
 Date: Sunday, October 4, 2015, 9:03 PM
 make a flood gage, it would seem that a simply pressure
 sensor like we use for atomosphere for balloon payloads
 would work.
 Just put it inside a pipe with a cap on the top and
 open on the bottom.  Then the pressure will vary with the
 height of the water.  Connect this to the analog input of
 an APRS tracker and you have a flood gage.  Calibate it
 with some testing and done...
 ANyone done this?
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