Liquid Level Indicating 1

[toastedhead]

Im looking for a liquid level indicator for a new test bench run by a Micrologix. I cant seem to find something that is capable of measuring a 15 oz difference in fluid level.

The problem Im finding is that they can cost upward of a grand - not feasible for what we're trying to accomplish.

 

[roydm]

There are lots of cheap options out there,
Do you need continuious level"
Fluid?
Level range in " or mm
Do you have an air supply available?

 

[toastedhead]

inch level - I dont really need continuous level but would like it if possible.

Ive got all the air you need - or I need in this case.

 

[roydm]

As you have air you can use an inexpensive pressure transducer with a bubble tube to measure the level. Cells are available for < $30.
Another option capacitance
A crude float type using a potentiometer.
It might be less hassle to just buy a low range DP transmitter on e-bay.
Check out the Omega catalog for level.
Roy

 

[HEC]

15oz diference, is around 30ml, I would doubt that a bubbler tube would have the required resolution to indicate that change. More infomation is required, what is the vessel shape and dimension, what fluid is being handled.

Mark Hutton

 

[roydm]

Here is a link to a few transducers from Honeywell. It looks as though the 22PCAFA6G with a span of 1# would work for you. It has an output of 42mV full scale so you could put it directly into a mV input or make a circuit with an op amp to boost it up.

http://www.e-sonic.com/aboutus/cat/P/pressure transducers.pdf

Don't try measuring your fluid pressure directly, that's why I suggest a bubble tube.
HEC, We use bubble tubes all the time for measuring very low differential on interface and density applications, mainly because our applications are very nasty and other types will not stand up.
Regards
Roy

 

[toastedhead]

Yeah, I checked Omega for level indicating. MOst dont seem to have a small enough res and the floater is 700 bucks.

The media is Turbine Oil - Texaco R&O 68.

 

[roydm]

I assume "turbine Oil" is non conductive, and not too viscous, perhaps you could just connect the cell I pointed to at the bottom of your tank to measure the static head directly. You would need a 10 VDC excitation source and a mV input card (or mV/mA converter) for the PLC.
I assume your tank is about 24" high.
Even if you dont use the whole range of the cell it should give you enough resolution.
Sketch Attached
Roy

 

[toastedhead]

Hey THANKS!!

I can build the tank to whatever spec necessary to accomodate the sensor. This should work out just fine!

 

[ozmosis]

This is a nice simple ultrasonic level device from Siemens:

http://pia.khe.siemens.com/index-process_instrumentation-the_probe-11159.htm

 

[roydm]

Yes, another good Canadian company "Milltronics" gobbled up by Siemens, not inexpensive though.
Roy

 

[danw2]

The Milltronics Probe is a first generation device with all the baggage of first generation products. It was replaced 3 or 4 years ago by the Probe LU, here:

http://pia.khe.siemens.com/index-process_instrumentation-sitrans_probe_lu-11157.htm

The Probe LU has far better functionality than the Probe.

Caveat Emptor.