How to select the boiler drum lvl transmitter?

Hi there,

This is not simple - look at previous posts in this forum. I have posted a solution for this to compensate for pressure, temperature and density changes.

It also depends on whether the boiler is new or exisiting as you might not have the necessary tap off points.

Basically you are using the principle of pressure measurement.

Good luck.

Craig

Hi there,

Refer to the following link: http://cr4.globalspec.com/thread/29556/Boil-Drum-Level-Transmitter-Range

I explain how you would use three PT's/DPT's if you prefer to measure steam drum level and how the use of the three eliminate the effects of the density; temperature and pressure fluctuations.

There is maths and it is very simple. Just remember P1 at bottom of drum, P2 at fixed point roughly midway and P3 on top of drum.

(P1 - P2) / (fixed height x gravity) = fluctuating density caused by temperature and pressure changes (pressure in drum, temperature differential between measured liquid and liquid in impulse line)

(P1 - P3) / (calculated fluctuating desnsity x gravity) = actual level in height.

actual level in height / total height x 100 = actual level in %

If you know the vessel dimmensions you can convert the level height to actual volume (with a strapping table)- it should give you better level control over the drum.

If you just use the above with level as a height % - you will get much better measuring accuracy without errors and huge fluctuations.

Regards,

Craig