I found an ultrasonic sensor I would like to use to monitor the level of a 20KL diesel tank (underground). I have tried to do my homework but have found conflicting references as to whether such a certification is required. The sensor is not certified EEx (but manufacturer says it is used by others for this purpose). I would plan to mount it on the manhole. Can it be done?

 

If you or your company, or your region of the world requires ATEX (explosion proof or intrinsically safe) sensors underground (and many do) there are dozens of ultrasonic level sensor companies (literally-- there are over 62 manufacturers in the world) and many if not most of them have hazardous area approvals on their transducers. It isn't hard to obtain. If the vendor you are working with says you don't need one, ask them for a certified letter from the President of the company that says that...

Walt Boyes
Editor in Chief
Control and Controlglobal.com
www.controlglobal.com

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Read my blog SoundOFF!! At www.controlglobal.com/soundoff

 

Actually I think it is not understood. I said underground tanks but it is not underground like in a mine. The tank is buried underground, but the manhole is at ground level.

 

I understood the application. It is a fairly common one. There are plenty of ATEX certified ultrasonic level transmitters available, as I said. Buy one of them instead.

However, here's something you may not have thought of. Diesel, like any hydrocarbon, produces fumes. When there is a temperature gradient from top to bottom of the tank, these fumes can stratify out and if the fume blanket is dense enough, it can cause a false echo and a false level. That's one of the reasons that ultrasonics are typically not recommended for level in hydrocarbon tanks.

You might want to consider a different technology, like magnetostrictive.

Walt Boyes
Editor in Chief
Control and Controlglobal.com
www.controlglobal.com

Mailto:[email protected]
Read my blog SoundOFF!! At www.controlglobal.com/soundoff

 

What does your local gas/diesel supply station use?
Regards, Phil Corso

 

In our part of the world, diesel (HSD - high speed diesel, used as vehicle fuel) requires IS/explosion proof rated instruments. As Phil pointed out, the local gas station would be a good starting point. Guided wave radar could also be used.

Regards,
Tomy Zacharia