Maybe something from the E & H range...

http://www.uk.endress.com/ ■

This particle size and density clays are notoriously difficult to detect. Paddle and vibrating type probes are no good at all. Your best bet will be capacitance type level probe. But all capacitance type probes will not detect it either. Best thing is to ask sales rep to bring a sample and test the probe in a bucket of material; try a few different brands. If your clay is in a fluidised state in the process then try to replicate the the process by pouring the clay in the bucket to check if the probe detects it and also what is the response time as if it does not detect it in time you will overfill.

Good luck and if you find any brand which works do share it with us. ■

Originally Posted by onyxgaze

Hi,

What is the best way of measuring level of hot fine powder?

The application is as below:

The powder is desolventised spent bleaching earth. It is constantly stirred using a paddle and it is kept hot at around 110 degC. The paddles move the powder around in the chamber and also drops it from the outlet into the next chamber and so on. The particle size is between 5-30 micron and the bulk density approximately 0.2 (200 Kg/m3)

The present mechanical float arrangement is ineffective as it sinks into the powder.

Any help here?

Thanks in advance.

We are Synatel Instrumentation based in Norton Canes GB

I agree with other comments, capacitance is the best method and products from our Digimatic range should be ideal. I have yet to see a clay that could not be detected but as suggested elsewhere, it would be sensible to test a sample. If you could let us know geographically where you are, we can get one of our authorised distributors to contact you and set up a test (adrian.m@synatel.co.uk).

The application should be very straight forward and temperature is no problem, we have probes capable of operating at up to 600 degrees centigrade. ■

In my hopinion a paddle level indicator is the best solution for your application since problems with bulks in general can be easily solved in this way. Some capacitance probes may be have some issue with dust because it tends to stick on the probe itself. Even if the powder is fine, it is possible to choose a bigger screw to have a better surface of attrition.

We can suggest you a couple of models in our production that can meet your requirements, if you would like to receive all complete information please contact us at camlogic@camlogic.it ■

We would offer the LS8 capacitance probe.

if you follow the link for further information

http://www.hawker-electronics.co.uk/magicapls8.

They are used to detect fluidised cement/air mixture. ■

From the original thread I would surmise that the clay is actually fluidised which is why the float sinks.

On this basis I wouldn't consider a mechanical paddle type device.

With a material temperature of 110 deg C I'd tend to avoid direct contact with the material.

So, back to the E&H web site and maybe a radar or ultrasonic non-contact device so the product temperature is not a problem. ■

Dear onyxgaze

May I suggest you have a look look at the Siemens LR460 radar level device for non contacting measurement. www.siemens.com/lr460

We are using this for homogenizing silos in the cement industry. You may also click on the link "References and Case Studies" for more examples.

If you have any questions or photos of the application, please feel free to contact me directly.

Best Regards ■

Dear Onyxgaze,

With respect to such problematic measuring conditions I'd recommend a radiometric level measurement. The components are mounted at the outer walls of the tank and a modification of the tank is not necessary. Heat, pressure, colour or acid materials don't affect the measuring performance. Even dust is no problem.

Often people are scared of having nuclear meausrements in their plants. However, there are extremely sensitive detectors on the market, enabling a reduction of the required source activity by up to 90%.

The company Berthold Technologies is specialized since 60years in this kind of measurements.

They provide individual assitance in project planning - non-binging and free of charge. You can just send over your application details. They have a worldwide network of subsidiaries and partners. www.Berthold.com ■

Radiometric will be a good application for this situation but in my opinion the price of the probe will be too much for this application.

Mr Sogeen can you kindly give us some ball park price for this probe ? ■

Originally Posted by Mantoo

Radiometric will be a good application for this situation ...

If you're happy to have a radioactive source on your site.

I'd go radar or ultrasonic non-contact first. ■

Dear Mantoo,

please understand that it is very difficult to state a price with the little information I have up to now. You can get a complete system from 7000€, but the price highly depends on the system configuration, the measuring range and which type of detector will be taken. Therefore I need to know more about the tank, like diameter, wall thickness etc. or a technical drawing of the tank if possible. If you want to have a technical evaluation, please don't hesitate to contact me directly. My email address is: Sonja.Geenen@Berthold.com

Regarding the radioactive source, I have to admit, that radiometric instruments are mainly chosen, when conventional measuring technologies fail. And there are lots of such applications. I am not sure whether ultrasonic or radar could work here reliably. But I know that radiometric measurements will do a good job in this case, because Berthold instruments are often used in applications like this.

Best regards ■

Hello Mantoo

As I re-read your question and the various replies, it's unclear to me if you would prefer a continuous level measurement or a point level measurement.

Also unclear is the design and size of the vessel, the range of measurement required or the location and type of fill or draw points.

Many of us would like to assist but you could help us help you by providing us a sketch of the application including some of the other details listed above, including your expectation of the equipment.

Best regards

Mike ■

Sogeen

Thanks. It has been a while since I put one of them in a process. I just wanted to know the ball park figure for it I don't currently have any application to recommend this probe. I think my last comment about price was correct.

I totally agree with you on the statement,”radiometric instruments are mainly used, when conventional measuring technologies fail” you have hit the nail in the head . It is the last resort. I don't think having radioactive probe is such a big deal on site, it is the price which normally is difficult to justify.

Deigner

I will totally disagree with you on this one. In my personal opinion ultrasonic and radar type level probes are useless in dusty environment. A good vendor will not even sell you one if you tell them it is for a dusty process. But you can disagree with me!

Micheal

I have not asked any question in the thread you need to ask Onyxgaze. I was just sharing my openion about Onyxgaze original question.

I can see some vendors active in this thread but no one has mentioned microwave type. I personally have no experience of them but you can get a transmitter and reciever probe which uses microwave. Would be good to know if any one has any working experience of microwave type probe for dusty environment. ■

Originally Posted by Mantoo

Deigner

I will totally disagree with you on this one. In my personal opinion ultrasonic and radar type level probes are useless in dusty environment. A good vendor will not even sell you one if you tell them it is for a dusty process. But you can disagree with me!

Micheal

I have not asked any question in the thread you need to ask Onyxgaze. I was just sharing my openion about Onyxgaze original question.

I can see some vendors active in this thread but no one has mentioned microwave type. I personally have no experience of them but you can get a transmitter and reciever probe which uses microwave. Would be good to know if any one has any working experience of microwave type probe for dusty environment.

First and foremost. My apologies because I directed my comments to he wrong person. Yes it should have been directed to Onyxgaze. Sorry Mantoo and sorry Onyxgaze.

Second. I must disagree with your comments to Designer. Many ultrasonic and radar devices have been misapplied. The same can be said for all technologies. Some seem to be more misunderstood than others.

I believe that most reputable manufacturers offer experienced application advice, free for the asking and would rather satisfy the customer need than sell a device into a bad application. I personally have suggested solutions our company does not have, such as radiometric devices, when I believed it was a better solution.

Finally, all ultrasonic devices and radar devices are not created equal. There are only a very small number of manufacturers with extensive bulk material experience and products that have been designed for this demanding environment. ■

Dear onyxgaze,

I can imagine it will be very dusty inside the bin, so I would not recommend the use of a ultrasonic device.

Of cause a nucleonic system would work, but it will take a lot of effort to install such a system and you have to care about the special requirements and the high price.

We, as a manufacturer of level devices with different physical measurement principles have very good experiences with microwave based systems.

The best will be non contact radar which is specially designed to measure bulk solids. The measurement principle Radar is nearly not influenced from dust and the high temperature.

We have installed some radars in a gypsum reactor were the temperature is even higher. The gypsum is more sticky then the bleaching earth. The sensor is mounted on a nozzle of 250 mm and the Antenna is app. 100 mm inside the nozzle, this keeps it more or less clean. If you expect still buildups a air purging can be used to keep the antenna system clean.

A good alternative if you need just a level switch is a microwave barrier. It is working like a light barrier but is much less sensitive against dust and buildups at the sensor. You can mount the unit direct in the wall of the bin or use a window made of plastic, glass or ceramic.

If you need detailed information please contact me or our representatice under www.vega.com.

Best regards

Jürgen ■