2 Liquid Level Measurment

[INSDE08]

Hi All
Can you please let me know which level instruments are better to measure the level of the oil on top of the water.The is around The tank is a closed tank.

Thank you
INSDE

 

[JLSeagull]

Displacement level instruments were traditionally applied to interface.

Guided wave radar is good for interface provided that the hydrocarbon dielectric constant is not too low. Normally this is not a problem. Magnetostrictive is not avvected by the dielectric. I prefer different technologies for the process control and safety shutdown measurements. I might look at GWR and magnetostrictive first; then consider other technologies.

I tend to avoid capacitance level instruments due to several issues.

 

[roydm]

JLS's Guided Wave Radar sounds like a good choice provided you don't have an emulsion layer.
A regular DP cell will work if you can get taps above and below the interface but you need to be carefull with the instalation detail.
We also use differential bubble tubes (Tantalum) in a particuarly nasty application. It's crude, old fashoned but it works very well.
Nuclear works well.
The Oil Patch still use a lot of displacers.
Roy

 

[tekparasite]

In similar applications of interface (level) measurements where radar is not a good fit due dielectric effects Displacement level instruments seem to work best. Fisher offers a product and Foxboro-Eckardt offers the same. The Eckardt one can do interface as well I believe.

 

[itsmoked]

What do you guys mean displacement? Do you have floats that float on the lower surface interface but not on the top one?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[roydm]

No, a displacer doesn't float at all it just weighs less as the liquid or interface rises.
Archimede's principle

http://library.thinkquest.org/27948/archimede.html

Roy

 

[Hellinas]

There is a level istrument from Enraf (we use it). With a float you can measure the oil and when you want you can measure the water. The principle is based on detection of variations in the buoyancy of a displacer. The apparent weight of the displacer is measured by a force transducer. So there is a step motor to change the position of the displacer. If u want i can send u the manual.

REMEMBER IS NOT GREECE IS HELLAS