Level Transmitter

I am in need of a level sensor for a bulk unloading silo. I have used the Ohmart Vega ultrasonic sensor in this application before, but they are very expensive. I was wondering if anyone had another brand or type of sensor that they have had success with. The silo is 53' tall and about 12' diameteer. The product is sunflower seeds. I need a 4-20ma signal out.

Thanks,

I am not sure it would be cheaper but Milltronics (Siemens) makes a good product; http://www.sea.siemens.com/ia/product/inlevel.html

I currently use a Rosemount guided radar unit (3301) to measure plastic pellets in a silo, not cheap though.
www.rosemount.com

I have used both ultrasonic AND guided radar (Siemens in both cases, I think) and will agree with Ken and Ron that they are not cheap.

They both worked great in my applications which were measurement of a thick slurry in a storage vessel (ultrasonic) and measurement of fly ash in a storage vessel (guided radar).

I guess you really do get what you pay for...

If you do opt for guided radar be sure you know what the material's angle of repose is and where the peak is located.

I've had pretty good luck with K-Tek's magnetostrictive transmitters, but they wouldn't work in your case although they have some transmitters that would. They are great for service and reliability.

http://www.ktekcorp.com/dnn20/default.htm

Just my opinion.

bill4261 said:

I am in need of a level sensor for a bulk unloading silo. I have used the Ohmart Vega ultrasonic sensor in this application before, but they are very expensive. I was wondering if anyone had another brand or type of sensor that they have had success with. The silo is 53' tall and about 12' diameteer. The product is sunflower seeds. I need a 4-20ma signal out.

Thanks,

Click to expand...

Try Endress & Hauser Brands, We use it here in our plant.
We have no problem using it for almost 10 years in our flour milling plant.

Siemens (formerly Milltronics) non-contact radar, the LR-400, will do it, but again, it isn't cheap. Reliable and accurate. I'm amazed at how easy the LR-400 has been to commission. Solids were always a pain before.

The Siemens ultrasonic will do it too, (MultiRanger) but it's fussier in its setup, angles of repose cause it more difficulty. With a 20m transducer, I suspect the cost is about the same as an LR400.

https://pia.khe.siemens.com/index.asp?Nr=4936

Dan

bill4261 said:

...but they are very expensive...
...anyone had another brand

Click to expand...

So the question seemed to be "I have something good but am looking for somthing cheap."

Answers:

1. ...will do it, but again, it isn't cheap
2. ...but they wouldn't work in your case
3. ...not cheap though
4. ...they are not cheap.
5. ...I am not sure it would be cheaper but

I have read many post about the poor writing but poor reading should be the main concern, or perhaps quantity outweights quality here. Who will be the first to reach 10 000 posts? The race is ON.

bill4261 said:

I am in need of a level sensor for a bulk unloading silo. I have used the Ohmart Vega ultrasonic sensor in this application before, but they are very expensive. I was wondering if anyone had another brand or type of sensor that they have had success with. The silo is 53' tall and about 12' diameteer. The product is sunflower seeds. I need a 4-20ma signal out.

Thanks,

Click to expand...

How about some background. If you are working for a reasonnable companie you will not save any money by installing something else. Testing, proof of work, confidence in the measurements are facts that you must address when replacing such devices. If you need 50 of them then its something else, If you have a local farm type distribution firm and money is a big issue, then for about %500 you can build your own system, PLC + Gearmotor + encoder is all you will need.

All depends on why you want to look for something cheaper ... or should I say, "less expensive "

Pierre said:

So the question seemed to be "I have something good but am looking for somthing cheap."

Answers:

1. ...will do it, but again, it isn't cheap
2. ...but they wouldn't work in your case
3. ...not cheap though
4. ...they are not cheap.
5. ...I am not sure it would be cheaper but

I have read many post about the poor writing but poor reading should be the main concern, or perhaps quantity outweights quality here. Who will be the first to reach 10 000 posts? The race is ON.

Click to expand...

I am going to take that last statement as a stab at me, not sure why but it appears to apply.

The original post stated "expensive" but did not include a cost so I have no way to reference what "expensive" refers to. I know the Milltronics equipment is accurate and reliable if properly matched and configured to the material etc involved. It may cost more or it may cost less, the only way to find out is for the person to take the time to obtain information and pricing for the equipment provided by the links.

I have no idea how the PLC, gearmotor, and encoder applies.

There are other options that may be less expensive in the long run depending on situation. It is possible to put tanks and silos on load cells to measure the weight of the contents. Weight, volume, and density have a relationship that can be determined to know how much material is added or removed.

Another option is just use something like bindicators for high and low level and use flow transmitters or rotary feeders to determine how much material is added/removed.

Technically there are numerous methods that could be used, ultrasonics/radar are not the only method that could apply.

As mentioned, one of the key issues with solids is angle of response or "bridging" which can lead to improper level readings. Bridging is when material may cling to the walls (and together) creating a bridge over the feed out point, in other situations the center of the material may cone, and of course it may cling to the walls and leave an open spot in the center.

Pierre said:

So the question seemed to be "I have something good but am looking for somthing cheap."

Answers:

1. ...will do it, but again, it isn't cheap
2. ...but they wouldn't work in your case
3. ...not cheap though
4. ...they are not cheap.
5. ...I am not sure it would be cheaper but

I have read many post about the poor writing but poor reading should be the main concern, or perhaps quantity outweights quality here. Who will be the first to reach 10 000 posts? The race is ON.

Click to expand...

I'm just trying to give my customer some options. Are they happy with the ultrasonics they have? Yes. Is there a better solution at a better price? Maybe. That's what I want to know. Do we have to go through the build your system? I got better things to do with my time and my customers money.

Thanks for all the serious replies.

Pulsar Black Box or Siemens Milltronics Sitrans LU.

That LU is a dynamite device. It does level shots that required top-of-the-line stuff 10 years ago. I must have a dozen LUs in service now.

But, the LU only shoots to 40 feet, too short for a 53' shot. It would not be suitable for a 53' shot.

Dan

bill4261 said:

I'm just trying to give my customer some options...I got better things to do with my time and my customers money...

Click to expand...

Thats exactly my point. I am always looking for better and less espensive levels x-mitters and when I saw your post title AND that it had a few answers I started to read expecthing some options would popup.

There are so many posts providing no help at all.


I have seen many custom built system that where reliable and cheap, since this is for other customers, you must have a standard of-the-shelf device. And this costs money.

In this case, the 53 feet is a major issue and maybee, just maybee the info will fly free.

Ron -

I am going to take that last statement as a stab at me, not sure why but it appears to apply.

Click to expand...

No, not you. Although I new it would look like it was I value the quality of your contributions in a way that could surprise many but that is for another post.

If you go the bindicator route, try to get the tuning fork type. They are much better than the paddle/clutch type. I am basing this statement on use with wood chips and saw dust.

I am not sure that there is a better way than ultrasonics. Initial cost is minor compaired to continous trouble with less expensive options. How well do sunflower seeds flow?