We have an application for low and high level point level monitoring for Silicon Magnesium feed hopper. The Product can have cake , can break down to lumps as it brittle. We want to avoid anything which shall protrude inside especially for Low level. The atmosphere inside will be dusty and it is combustible dust , as well there are possibilities of spark, Hence looking for a sensor which can work from outside the wall of the vessel.

In one of the forums Ultrasonic sensor from outside the vessel wall has been suggested for a different application . It looks possible solution as the vessel wall could fall in inactive zone.

It shall be great to have some reference and if anyone has done similar application. Also suggestions on other types suitable would be welcome.

The Steel Hopper is small of about 8 tons with a height of about 3 meters.

Thanks in advance,