Welcome to the world of level detection salesman.

You should have started out by weighing the silo, or as a minimum looked at the cost to retrofit with load cells. If it is a 3 point or 4 point silo, you can put a weighing device under one support and get 2-4%. You can do all support points and of course get better accuracy. If it has a full continious base ring, adding load cells is difficult unless it is free standing on 4 legs.

Ultrasonics DO NOT like dust or cones or varing angle of reposes.

Your only other option is to put RF or vibratory, or contact probes every 3-5 meters up the side and hope they work.

Strain gages are available, but should only be used if the supplier knows what he is doing.

Send me some digital pictures and I will try to help you more. ■

Ultrasonics, when properly installed and tuned will work in dusty atmospheres with varying angles of repose. The issue in the cone area is an inability to adust to the cone as the material level goes down. Transducer location and aiming are the most critical in this type of application. The transducer should be located 1/2 radius opposite the fill point and not between the fill and any dust collectors. Aiming of the transducer is slightly past the draw point. This will give the most consistent performance. Using variable gain will also be of benefit.

The use of level to convert to weight is, at best a 10% system due to angle of repose, compaction, specific gravity. By the inverse, using weight to convert to level is also, at best a 10% system for the same reasons. If the intent is to understand how much room is in the silo, then ultrasonics or yo-yo will work. The use of radar and microwave, guided or not, is dependent on the materials dielectric constant. Anything less than a DC of 2 is suspect. Guided type are in contact with the material and exhibit a pull of approximately 7,000 to 10,000 psi on the connection point at the top of the silo. Radar will also have the same issues with angle of repose, etc.

Direct support weight will give weight, but a high level probe would be recommended to prevent overfill.

Depending on the support structure, bolt-on strain gages from KM may also provide a more accurate weight system that meets your requirement ■

I need a little more information on your application before I can recommend a specific replacement model. What are the temperatures and pressures inside this silo? What is the diameter of the Silo? Is the silo smooth wall like in concrete, welded steel, or bolted steel, or is it rough as in corrugated construction? What is the angle of the hoppered bottom? These attributes all affect the accuracy and reliability of Ultrasonic level measurement. Have you verified that the temperature compensation in your system is working correctly? How close is the ultrasonic transducer mounted to the filling point? Have you contacted the manufacturer's Tech Support and asked for assistance? Do they and the existing level system have the capability to look at the return echo signals via modem?

What is the particle size of the "Chrome" and what are the other materials? What are their densities and angles of repose? Are the materials electrically conductive, and will they leave a coating on objects in the silo? Do you need a level measurement while filling? How often do you need a new measurement? What types of outputs are desired if any, or would a display only suffice? Where will the display be located? Is there a need to remotely query to level measurements offsite as for vendor-managed inventory?

Are there any chemical compatibility issues with these materials? Do any of the materials present a dust ignition hazard? Are there any obstructions, mechanical supports, or flow aid devices in the silo?

All of these characteristics and requirements will influence the selection and resultant dependability of the "Bindicators." ■

Dear Sir,

The level indicators for bulk solid silos were manufactured by us had been used under similar or worst conditions since more than ten years, in Turkey and abroad. we can give you more information if you contact us.

Best regards

Mustafa Kemal Yunel

Yunel Elektromekanik Co. Ltd.

Esat Caddesi No= 34/5

Kucukesat 06660

Ankara/Turkey

Phone = +903124193285

Fax = +903124193289

e-mail = mky@yunel-birlik.com.tr

URL = www.yunel-birlik.com.tr ■

I saw your problem. may be can you solve this using nucleonic level guages. as these level guages are fitted outside the silos and moreover they are not disturbed by dusty atmosphere. but at present i cant tell you the exact manufacturers. if i come across i shall inform you.

Mohamed Asadullah

asadullahasad@rediffmail.com ■

We are manufactures of level devices since many years. For difficult conditions such as high dust and vibrations, I recommend the yo-yo principle for measuring level. It seems to be a „old fashion“ principle, but you would be surprised how much microprocessor intelligence it has. However, the sensing weight of the yo-yo goes straight down to the product and up again. There is no influence of dust, vibration or noise of pneumatic conveyors. And it is not depended on the dielectric of the material. If you need some more information, please contact me:

MAIHAK AG

Poppenbütteler Bogen 9b

D-22399 Hamburg

Telefon 0 40- 2 78 94- 312

Telefax 0 40- 2 78 94- 362

frank.wengler@maihak.de

www.sick-maihak.de

http://www.sick.de/de/products/categ...nitors/en.html

Frank Wengler ■