Calculating LRV/ URV of a Bubbler Level System

K

Thread Starter

Kazim

Hello everyone,

We have a Bubbler type Level Measurement Sensor installed at our site. It measures level of water in a basin which has a depth of 5000mm. The sensing air tube was dipped in water almost till the ground but now we had to lift the tube a little, 200mm to be exact.

The LRV was 0mm and URV was 5000mm earlier. What will be the new LRV and URV? Can anyone pl help!

I have made a drawing which will be helpful to explain the situation. Its placed here.

http://postimg.org/image/yaj1jcwut/
 
Your bubbler can not 'see' any head pressure lower than its elevation, so you can not measure any of the 200mm depth below the bubbler tube.

The way it's installed, the transmitter's measurement output will span 0-4800mmH2O. You can change the URV to 4800 or you can leave the URV at 5000mmH2O (because it's a round number) with the understanding there's no way for the level to ever go above 4800mm so the transmitter will never output a value from measured 4800-5000mm (equivalent to physical 5000-5200mm).

Your HMI/DCS/indicator can arbitrarily add 200mm (as an offset/bias) to the transmitter's scaled output, so that the measured output value matches the physical level.
 
first find the clearance of your dip tube.

say if it is 200mm.

total height of the tank = 5000


so here you go..

LRV = -200 * density of the liquid

URV= (5000-200)* density of the liquid

that's it... you will get the correct level of the liquid inside the tank... but you cannot get any variation in that 200 mm clearance gap...here in this case you will get a 4% reading on the tx when the water level crawls down below 200 mm.. ou will get reading only beyond 200mm level.
 
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