View Full Version : Hydrostatic sensors

02-01-2007, 07:38 AM
I am looking at making a real-time liquid management system.ˇ Has anyone done this before, or know where to get some hydrostatic sensors.ˇ I will have fluid depths up to 10 feet deep.ˇ Another project I am looking at is measuring the weight of the fluid with weight sensors underneath storage tanksˇthat hold 50, 75, 150 and 350ˇgallons of fluid.ˇ Could someone please point me in the right direction for sensors that could do this.

02-01-2007, 10:35 AM
Wrap a spring in waterproof plastic. Put a waterproof linear potentiometer inside this device. When you compress the spring, you will change the output voltage because of the potentiometer. Put this whole assembly inside a strong can shaped metal container that is a tube. It is open on both ends. Under pressure the can will not deform but the spring inside will. Use the Stamp II to detect voltage changes. Voila, you have a hydrostatic sensor that can sense depth for under 5 bucks. Since it will not be over 10 feet deep, I think even a tin can will work. Here is even a pic:
If you have the bucks, just use the commercially available product:
www.emesys.com/OL2level.htm (http://www.emesys.com/OL2level.htm)
There's a command that you can use to detect analog voltages with the Basic Stamp 2, but I forgot what it was....
For a weight sensor, use the spring without the outside tin can and you're set.

Post Edited (latigerlilly) : 2/1/2007 3:43:04 AM GMT

02-01-2007, 10:50 AM
Here is a couple I found on Jameco... not quite sure if they are what you want

www.jameco.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10001&langId=-1&categoryId=352520 (http://www.jameco.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10001&langId=-1&categoryId=352520)

02-01-2007, 11:38 AM
We used a sonar level finder in an oil tank application once. Look down, figure out how close the surface is, figure out how deep, calculate volume in barrels, call home when you have a truck full.

02-02-2007, 05:20 AM
I am trying to monitor fluid volumes in chemical totes and water tanks real time while the fluid is being pumped. It has been since college that I have used my Basic Stamp, but I figured it would do good for an initial trial. Float style monitoring systems has been used in the past, but they have many maintanence issues due the chemicals that are in them.

02-02-2007, 10:09 PM
I am still in the brainstorming stage of this project, so sorry for the lack of details, I'm sure they will follow in the months to come. Right now I'm trying to get a sense of the products that might be available for this sort of project, or if anyone has done anything like this.

The reason I mention 2 methods is that, one tank will hold over 20,000 gallons of fluid so I figured weighting the tank would not be reasonable, but rather measure the depth of the fluid and calculate the volume as close as reasonable possible. I figure +- 200 gallons is reasonable. The fluid in the tanks would range from fresh water to 28% KCL water. Therefore I would have to have an input for the density of the fluid.

The other method of weighing the tanks is due to the smaller volume, 50, 75, 150 and 350 gallon totes. These totes also contain corrosive chemicals, so putting anything in the chemical would cause problems. The accuracy on this would need to be much better in the range of +- 1 to 5 gallons.

Robert Kubichek
02-02-2007, 10:50 PM
For the large tank, I would use a pressure sensor connected to the bottom of the tank.
A commercial one with a stainless steel diagram would be best due to the corosive nature of the contents.
You, "I figure +- 200 gallons is reasonable." should be able to get a much better result than this...

For the small tanks, I would use a stainless steel non-magnetic tube holding hall effect sensors, and surrounding
the tube is a float with a potted magnet, the float is covered with teflon or any non corosive covering...
The amount of hall sensors dictates the accurracy you will achieve." +- 1 to 5 gallons."
OR, you can go the route above for the large tank, but just get a more sensitive pressure sensor.

You will have to calibrate the sensors for optimum accuracy, but they should also come from the manufacture,
with that data as well..

Bob 8)

02-03-2007, 01:08 AM
HI Pellerin,

I would give a try to this www.parallax.com/detail.asp?product_id=30056 (http://www.parallax.com/detail.asp?product_id=30056)

This sensor in a fitting tap stile with a piston or such pressing on the surface of the sensor.......

it should be possible to relate the weigth/surface to the height of the column ence the total content of liquid, could be possible density too?
it's unrelated from temperature in wich the weigth remain the same only the volume changes....
it can be done with BASIC Stamp, SX, Propeller, Analogic.

Some design tougths should be given to the against chemicals, resistance to temperature, humidity, vibrations, and wathever.

Just a suggestion


P.S. Also with an infrared or sounder stile (provided this methods are not endangering the chemicals or reactions taken place).
it should be possible to have somehow a reflection from the top of the tank to the liquid's surface in a test pipe connected in parallel to the tank.

Post Edited (ellizard) : 2/2/2007 6:15:48 PM GMT