need a sensor to measure fluid level, of turbulent drilling mud

[RichCWUK]

Hi,

I'm in process of getting an impact and abrasion testing rig commisioned. It simulates some parameters seen when drilling...

It has a tank, full of drilling mud, which needs to be monitored. If the mud levels are too low, we need it to shutdown (via a computer system).

The sensor needs to be...
-Corrosion resistant
-Submersible
-Extremely durable
-Cheap
...and it must give a +/- 10V output, so we can hook it up to our rig operating system.

I have seen a few examples. Float devices aren't practical as the mud is sloshing about all over the place and ultrasonic sensors are most likely expensive.

Any ideas of what to go for?? I'm a materials engineer, so i have little experience in this!

Cheers,
Rich

 

[VEBill]

Weigh the tank.

 

[RichCWUK]

i cant weigh the tank, it's fixed on. We need an electronic sensor which we can 'plug' into our computer controled monitoring program.

say, the mud level gets too low, we need a sensor to detect that, send a signal (10V) to the computer. The computer then shuts the test rig off, to prevent damage to specimins and the machine!

any ideas?

 

[waross]

Old school, bubble tube?
Air is released through a small orifice into a tube that extends to the bottom of the tank. The head or level is inferred from the air pressure in the tube. It is fail safe in that if the air supply fails, the pressure drops and the system shuts down on low level.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[davidbeach]

-Cheap

You get what you pay for. Think of it as insurance; how much would you pay to ensure that the system always shuts down on low mud? The appropriate sensor will have a low cost compared to risk. If the cost of failure is so low that all you can afford is cheap, just use the operator's eyes.

 

[jraef]

I've done mud. Not as tricky as you might think. The entire Sewage industry has to deal with "highly viscous materials" that are, to be honest, a LOT more challenging. Ultrasonic works great, "expensive" is a relative term. I like them because you can set and forget. No contact with the fluid has distinct advantages in the long run, trust me. I like Milltronics (now owned by Siemens), they are very simple and robust.

There are also a myriad of submersible pressure transducers as well all of which were designed to replace bubbler systems. The drawback to a bubbler is that it needs a compressed air source and if you don't have one, adding even a small cheap compressor adds a LOT of failure possibilities and maintenance. The pressure transducers work basically the same way; they are submerged into the slop and have a membrane over a strain gauge that gives a signal to a transducer in your control panel which provides a proportional analog output r set point relay closures.

Do a search for "wet well level transducers" and you will find thousands of choices.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[MacGyverS2000]

Thinking outside the box here for a moment...

Any reason you can't use a sealed pressure transducer on the outside of the tank with a flexible membrane on the tank wall? More mud creates greater pressure against membrane, causing sealed pressure transducer to recognize level.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[IRstuff]

You could roll your own ultrasonic sensor. Parallax's ultrasonic sensor and one of their development boards would only set you back < $200

TTFN

FAQ731-376

 

[roydm]

You say float devices aren't practical so I guess you aren't ruling out a discrete switch. What about conductivity like a Warrik probe, cant get much cheaper than that.
If you need analog a capacitance probe or flange mounted DP as Mackgyvers suggested
Roy

 

[RichCWUK]

jraef and macgyver, your solutions seem plausible. I'll give them a go. Thanks

 

[BJC]

Float switches are the most rugged and relaible. Look at the ones that are used in sewage lift stations.
You may have to wire in a time delay circuit to average out the sloshing but theya are very rugged.

 

[electrician1]

We are dealing with mud tanks as well, and believe that ultrasonic sensors are the best solution.
We use Prosonic M type,it's very reliable and work's perfect.Float devices are not the best solution,neither pressure transducers especially if specific density of the mud is changing