level sensor

What is the best level sensor for water I mean the most accurate for measurement, not only level but also total in gallons in real time?

Wow, this is a good question. You mean you want to know the level in a particular vessel, as well as a totalized flow from the particular vessel? I don't know of one instrument that does both off the top of my head, without assuming some very simple geometries. For example, if you had a tank that was the exact level of a parshall flume measurement point, I suppose you could get the level and the totalized flow, but then again, I am not sure you would actually have flow through the flume.

I would love to hear others responses to this, as my instrumentation knowledge is a few years old, and I could be overlooking something.

Richie,

There have got to be as many ways to measure tank level as there are tanks in the world.
If you could be a little more specific on the storage vessel type and type of water (ie clean, dirty, foamy, RO/DI) you might get more specific responses. Each application is different.

Marc

I am using a Banner QT50ULB to measure the levels of our tanks

From the variation in level you can work out volumes used. You just need to know before you fill or empty a tank so as to log the previous level.

It is relatively accurate.

Ultrasonic, like a Siemens Hydroranger or Pulsar black box have built in tank volume measurement software and will output volume or level or distance depending how it is configured.

Some hydrostatic sensors like those from Krone will also measure tank volume.

I think the Pulsar units have the best selection of tank profiles.

you could also use a pressure transmitter mounted at the bottom of the tank. you'd use the hydrostatic weight of the water (in inches or psi) and conversion formulas to figure level and gallons.

A good unit for this application would be the "Waterpilot" from E+H and is cheap

In my opinion, nothing beats load cells for accurately measuring the amount of stuff in a tank. Granted, it's an expensive method but you did ask for "BEST". Out of all the other methods mentioned, load cells are the only one that directly measures the quantity of stuff in a tank. All the others have to compensate for tank shape, agitators, baffles etc.


That said, water is generally very easy to measure (assuming for the moment that it's not high purity like DI or RO). Ultrasonic, RF admittance, Radar, dP cells will all work very well.

mellis said:

In my opinion, nothing beats load cells for accurately measuring the amount of stuff in a tank.

Click to expand...

I agree. Weight is the true measure of how much stuff is there independent of temperature or foam or whatever. It works with any shape tank. However it may not always be desirable for materials which have a large thermal expansion coefficient.