Posted on June 28, 2000 at 05:07:34:

In Reply to: powder silos level measurements with ultrasonics posted by Marcos M. Pimenta on June 16, 2000 at 16:09:06:

Dear Sir,

we also have experiences in powdery materials. For ranges up to 20 meters the microwave guided system called Levelflex is used. In cases of longer distances we are able to measure with ultrasonic systems in static conditions. Due to the installation conditions, a reliable measurement under dynamic conditions were not possible. The created noises during filling put the signal in an area where it can not be evaluated any more. E+H uses a so called filling filter. The filling filter can be activated when the signal is lost. Automatically the output signal increases with a specified slope. For the user it seems that the system is measuring. In a certain distance a clear singal will be evaluated again and the real measurement continues.

best regards

Ralf Matthaes

Instruments International ■

Posted on June 28, 2000 at 03:35:57:

In Reply to: powder silos level measurements with ultrasonics posted by Marcos M. Pimenta on June 16, 2000 at 16:09:06:

Sirs

Correction - on lasers it should have said did have available (bust dust problems were to great)

Mel Henry ■

Posted on June 26, 2000 at 13:15:32:

In Reply to: powder silos level measurements with ultrasonics posted by Marcos M. Pimenta on June 16, 2000 at 16:09:06:

Dear Mr. Pimenta:

Being quite familiar with non-contact ultrasonics, it is an effective technology in simple solids applications. Laser on the otherhand, is a much more effective technology for difficult powder and bulk solids level measurement when it comes to large distances down to the level; presence of dust; and varying angles of repose. Furthermore, it is more accurate and updates level at a much faster rate. Other benefits include:

· Ideal for low dielectrics at any range

· Performs well in difficult dust or vapor applications

· Ideal for high pressure and temperature applications

· Available with a wide range of mounting accessories for nozzle and surface installations (wall or roof)

· Narrow beam angle (0.28 degrees) offers greater application flexibility

· Orientation of the signal with process level is not critical

· Quick and easy setup with a hand-held programmer

· 4-20 mA output, with RS 232 and 422 serial ports

· FM and CSA approvals with NEMA 4X and 6 (IP67) enclosure

Please visit our website "tn-ksi.com" for more information on the Accu-Pulse laser technology.

Sincerely,

Michael Barber ■

Posted on June 23, 2000 at 08:47:42:

In Reply to: powder silos level measurements with ultrasonics posted by Marcos M. Pimenta on June 16, 2000 at 16:09:06:

Dear Sir,

Most times problems are caused by the air-circulations in the silo during filling, or by material faling in front of the sensor.

It will be necessary to install sensors with high sensitivity.

Also the position of the sensor versus the filling point and the air extraction point is very important.

Kind regards

Paul Janssens

Kistler-Morse Europe ■

Posted on June 28, 2000 at 03:29:49:

In Reply to: Re: powder silos level measurements with ultrasonics posted by Paul Janssens on June 23, 2000 at 08:47:42:

Sirs

I agree with Paul Janssens of Kistler regarding nature of problem ie airflow across the sensor(dragging the echo away).We have available in our range Ultrasonics,Radar,Laser and TDR(radar on a rope).

We can therfore look at it very objectively.Our suggestion would be to use TDR which is unaffected by any such conditions.

Mel Henry. ■