Liquid level measurement with rate of change alarm

[Enzo_UK]

I would like to come up with a system to display liquid level inside a container, I doesnt have to be very accurate as is quite large at 2600 litres (about 570 gallons)

I basically just need about 10 levels of measurement, with a low level warning, which itself doesnt seem too bad.

The only other thing is I would like it to also have a rate of change warning, so if it dropped by more than 1 level in for example 1 hour, it would also trigger an alarm.

I am thinking of going for somthing ultra-sonic, but have not had an previous experience using them, so dont really know where to start.

Can anyone point me in the right direction of sites that may have any plans for using ultrasonics for liquid measurement to use as a starting point.

Any help is greatly appreciated.

 

[slosjo]

Nice ultrasonic sensor

If you don't mind spending a little money, check this out:

**broken link removed**


I have used this one personally and it is very accurate up to about 10 feet and down to an inch. The response time can be very good as well, depending on your code.

 

[weglobal]

Hi,
I am doing a project almost like this one the diference I only car about 2 point on in the button of the taknf when the water is around 1" high and the other is one the wtare is 4" hight the prblem is that my tank is only 6" deep so I tried PING but did not work because is to close also the 1" resolution is not gopod I need a least 1/4 or less/
I am trying to do with one transducer 210Khz could anybody help me please ?
Thanks

 

[KMoffett]

If you can have probes in the water, and the water is not ultra-pure (non-conductive) this two-point controller would work. **broken link removed** Very accurate. Replace their sensor with three stainless steel rods. One below the minimum level, one at the minimum level and one at the maximum level.

Ken

 

[weglobal]

KMoffett
Thanks for you help
I cannot do it becouse the liquid type could chnage from very lo PH to accid level and temeprature change is a big problem I tried with capacitance and did not work so that why I am trying with sonar
Thanks

 

[ccurtis]

I know of one type of sensor that is a series of reed switches that are enclosed in, and span the inside of, an aluminum tube. The tube spans the depth of the tank. The tube fits inside the donut hole of a donut shaped float containing donut shaped magnets. Of course, the rate of change can be determined by the measuring the time it takes the float to switch from one reed switch to the next.