level measurement

All the Leaves are Brown, and the Sky is Gray above your Silo Level Indicators....

So here I am reminiscing about a birthday celebration I attended last night and The Mamas and the Papas jumped in my head as I flashed back to the 60's and 70's for a minute or two. One of our staff cruised by my office door with a used sensor over his shoulder that was in need of evaluation. Since I like examining equipment that has been working in the field for extended periods of time, I  got up and followed it to the test area where we examined the unit. It was a SiloPatrol SMU that was produced in 2004. Upon removal of the cover, a small amount of white powder spilled out on the bench. After seeing the powder and knowing the SMU was sent in because of a Motion Error, we directed our attention to the wiper seal and discovered that it was packed hard in gypsum powder to the extent that the 3/16" SS cable could not travel freely through the wiper. So, finding out what I wanted to know was accomplished I then returned to my desk. "What does this have to do with dead leaves and a dark Autumn sky?", you ask. It got me thinking about a similar unit I worked on a couple of years ago in the dead of winter with 22 knot winds and temperatures in the high minus teens. If the maintenance staff at that facility had performed a preventative maintenance inspection in November, I probably would not have been getting frostbitten fingers in January. (It is difficult to thread a 3/16" SS cable and a compression sleeve and thimble with heavy gloves on.) So to conclude, If you are the proud owner of any brand of plumb bob style continuous level sensor, you might want to think of getting someone aloft to check everything out before the snow flies. And if you live where it is hot by 10AM, you still might want to pull a PM to check for worn parts so you can order them and change them out before your system actually breaks down. I almost forgot to mention that we do have part kits to allow the owners of our original SMU design to convert over to the new wiper seal compartment that eliminates the necessity of cutting your cable to change out a worn out or clogged wiper seal.
Greg DeRudder
Product Manager
gderudder@monitortech.com

Technorati Tags: level sensor level measurement bin level indicator level control solids level indicator

High Temperature SafePoint Rotary Paddle Sensor Solves Titanium Application

Ball Sales and Engineering, the Monitor rep in CA, OR, WA, AZ, NM, NV, was working with a large company who supplies high quality titanium metal products. Titanium is used in hundreds of diverse aerospace, industrial and emerging applications where no other metal is as reliable or economical, especially on a lifecycle costing basis.

The customer was looking for a level control to be successfully used as a plugged chute detector; the customer had experienced problems with RF probes from another manufacturer. Plugged chute detection is critical to make sure that material is flowing properly through a process; a plugged chute condition can cause problems with transfer rates, mix ratios and production “down stream”.  Monitor offers several options for plugged chute detection, click here for more information.

The target materials are Rutile Ore with a bulk density of 150 lbs per cubic foot and Petroleum Coke with a bulk density of 53 lbs per cubic foot.  The material characteristics of the Rutile Ore can be described as having a “sand texture” and the Petroleum Coke is “granular”.

This application is made even more challenging due to the extremely high temperatures involved, the ambient temperature ranged from 100 degrees F to 150 degrees F and the internal process temperature could be as high as 750 degrees F.  But wait, this gets even better; the internal air in the feed pipe being monitored for a plugged chute condition is a gaseous chlorine, which if combined with moisture of any kind creates Hydrochloric Acid!

The Sales Engineers with Ball Sales worked with the customer by gathering additional details and suggested that the best solution would be for the customer to install a high-temperature SafePoint rotary paddle bin indicator.  The hi-temperature SafePoint unit can be used in applications up to 750 degrees F.

The SafePoint will not be challenged by the fluctuating dielectric constant of the target material or the possible changing temperatures that caused the issues with the RF probe they first tried.

For more information on Ball Sales and Engineering please visit their website www.ballengineering.com   Ball specializes in analyzing applications and recommending a correct, value-added solution for your most demanding applications.

Please feel free to contact us directly at Monitor with any questions...www.monitortech.com

Scott Bonine

Technorati Tags: Level measurement basics bin level indicator level control solids level indicator

plugged chute detector plugged conveying line solids flow detector

Something ate my level probe!!!!

 

Last week I received a telephone call from our representative in the Carolina's, Bobby Vaughn of The Vaughn Company (www.thevaughncompany.com). Amazingly, in spite of our language differences, we were able to communicate (Bobby says I only speak "Yankee"). Bobby had received a call from a customer that had purchased one of our RF capacitance probes about four years ago.  Recently they were having some issues and they decided to take a closer look at the probe.  Much to their surprise when they removed the unit they discovered that the once mighty stainless steel probe was gone! It turns out that the probe was installed in Chlorine water, and while it took four years the Chlorine water had eventually dissolved the probe.

This is obviously a very infrequent occurrence with our typical customers but I feel that chemical compatibility issues are something that we should be cognizant of. I am sure that most customers are aware of things at their facilities that may be chemically aggressive, so often they will bring it up first. Also, there are many "chemical resistance charts" available on the web that will show chemicals and how they effect materials they may come in contact with.  One chart I use rates things on an alphabetic scale with "A" having "No effect-Excellent" to "D" Severe Effect-Not Recommended. I reference this chart when I get a question concerning this issue, most of the time our products will work great with the majority of the materials we "target" with our level controls so it is not a problem.

If you have any questions concerning an application please give us a call, we will be happy to work with you to find a solution. Thanks, Scott Bonine

Technorati Tags: Level measurement basics bin level indicator level control solids level indicator

Silo Track Software...Don’t sweat the small stuff

I was happily sitting at my desk today, reading up on how one of my colleague was spending his week when the phone rang from a frantic caller wanting to know why his SiloTrack inventory software wasn’t working with his SiloPatrol® level sensors. He had installed his SiloTrack software around 2 years ago and didn’t have a problem with it until he received a call from his inventory controller letting him know that both of his second generation SiloPatrol SMU’s were reporting a COM error in the software. From the get-go, he was adamant on getting support, and from the sounds of it, he had not been in this situation before. For the record, his electricians had to do some work on the vessels, so the power was turned off to the sensors the previous day, but upon restoration of the power, the sensors reported a COM error.

 
I proceeded to walk him through the normal rings of troubleshooting a COM error in SiloTrack.
 
Power? Check. End-user was able to climb up to the sensors and perform a manual measurement. (Users who may have problems like this frequently, listen up)
Good connections? Check. End-user was also able to verify that the sensors were properly addressed and that there was no solder bridging between the two wires of the RS-485 cable on the DB-9 connector. At this time, I presumed that he had measured the resistance of the two wires. While this is a good practice, you must remember to do this when all power to the sensor(s) is OFF. This measurement, in a good environment, should read about 120 ohms depending on how much network termination resistor switches are in the ‘on’ position. (Remember, you only want the end points of your network to have those switches in the ‘on’ position) This proves that there are no breaks in your RS485 line running from the PC to the sensors. But wait! I would imagine when he had measured the resistance, he had accidentally pulled out the Y-cable from the RS485 PCI card and it had fallen on the floor. The call had dropped for some odd reason, and I was about ready to yank all my hair out while I was calling him back, only to him getting on the phone and explaining what had happened.

At least he knows now exactly what to check for when he has this problem! I hope that all the other users who may have this problem check all the necessary things, as well as checking to make sure all the connections into your equipment are sound! Don’t sweat the small stuff!

John Mish
Sales / Technical Support
Monitor Technologies

Technorati Tags: level sensor level measurement bin level indicator level control solids level indicator

Avoid Obstructions When Installing A Guided Wave Radar Sensor

Guided wave radar instruments, like Flexar®, use a cable as a wave guide or antenna.  The microwave energy pulses down the cable antenna and reflects off the material surface.  The reflected pulse travels back up the antenna to the transceiver. 
Obstructions near (within ~12”) of the cable antenna have a high probability of interfering with the microwave energy measurement pulses. Just think of attempting to make a cell phone call while standing inside a metal doorway.  Sometimes it works but most times it doesn’t.
Some obstructions result in crazy reflective echoes.  These reflections can exceed the strength of that from the material surface.  To cancel such large reflection an irritating and often substantial dead zone has to be created along the length of the wave guide cable antenna.  Not good.

Obstructions also cause signal degradation.  Like the cell phone example, energy from the wave guide cable can be bleed off onto the obstruction.  Because the Flexar guided wave radar sensor is measuring and not cooking the silo contents the emitted energy level is rather limited.  If enough of this energy is bleed off there is a possibility that insufficient energy will remain to make a viable reflection.

Vessel View, Exterior

Vessel View, Interior

 

   

Pictured above is one of the most common examples when it comes to interfering obstructions.

For unknown reasons the factory provided application and mounting recommendations were disregarded and the Flexar instrument was mounted to the pictured stub nozzle.  Under the best of circumstances the height of a stub nozzle should not exceed the inside diameter.  In this example that guideline has been completely violated. As shown, the nozzle protruding above and below the roof line well exceed the inside diameter.  This resulted in crazy pulse reflections which were so strong that the level signal would not follow the
material level.  The short term solution required a six foot dead zone to be created on the top portion of the vessel. 
This meant the customer lost the ability to monitor the material in the upper six foot section of the vessel.  Not good. 

The long term solution is to move the Flexar to the  center of the forward plate which sits atop a large nozzle which better conforms to the mounting guideline.

Andy

Technorati Tags: Level sensor level measurement basics bin level indicator level control solids level indicator guided wave radar 

 

A SINGLE Wireless standard for the process industries? Not a chance!

Well here we go again.  I just read some editorials in the latest issue of CONTROL magazine.  Greed and ego are proving to trump logic and reason once again.  Users need a standard, a single open protocol standard for Wireless communications.  In existence today with products being marketed offering this capability are Wireless HART.... that's it.  The Honeywell wireless is a proprietary protocol that Honeywell is batting to shove down the throats of the ISA100 committee that have been gathered for three years now trying to develop a standard.  While the battle has been quietly, and sometimes not so quietly, been raging in the ISA100 committee, Wireless HART has been working hard and growing its installed base.  By the end of 2008 there will be even more products offering it, including the measurement instrumentation giant Endress & Hauser and Emerson Process.  I'm with them, Wireless HART is the way to go... and so is wireless in general.

For level measurement applications, especially those used for inventory monitoring and management, wireless offers the ability to save money by eliminating the cost of hard wiring and also enabling the connectivity of sensor and system across physical barriers to hard wiring.  But this wireless application is not anything new.  Many vendors have been providing wireless communications using proprietary protocols for years.  The new wireless standards hope to offer interoperability from application to application and vendor to vendor.  This is a good idea.

Joe

Technorati Tags: Wireless Sensor Communications level sensor level measurement bin level indicator level control solids level indicator guided wave radar 

Hydrostatic Level Measurement is still "King" for liquids

In a recent article published in CONTROL magazine author and writer Paul Miller makes the point that hydrostatic head pressure measurement is still a most common method for measuring the level of a fluid in a tank.  He makes other points too, more important in his article than here.  The point I wish to make here is that this technology for the level measurement of fluid in a tank has been around for many years and is a simple and economical way to measure tank levels, while its "flash" is far less than newer technologies like radar.

Let's take a quick look at how pressure or differential pressure transmitters are used to measure the level of a fluid in a tank.  Why type when I can reference you to a perfectly fine tutorial from Wikipedia so follow this link.  Some application issues affecting the use and performance of hydrostatic level measurement include the cleanliness of the fluid, the corrosiveness of the fluid and how stable the specific gravity or density of the fluid is.  Like other technologies used for level measurement of liquids, there are limitations.... which is why so many technologies exist today and they are all viable in their own right.... EXCEPT for using ultrasonic to measure continuous level of powders and other bulk solids... No No No!

Really though... please read Paul's article "Pressure-Based Level Measurements Keep Getting Better and Better" because it is well written and a great short tutorial on this subject (it also keeps me from having to write it for you LOL).  It's great and a reminder how these devices work well and some of their limitations.

I went back and took a look at the most recent market study report I have available.  Hydrostatic pressure based level devices represent about 48% of all continuous level measurement devices bought each year!  That's huge!

Joe

Technorati Tags: liquid level differential pressure level level sensor level control

Level measurement basics ..........

Why do level measurement applications provide some of the most difficult challenges?  Why are there so many technologies available?  It should be easy, right?  Not necessarily.  I have never been one to want to say a whole bunch when a picture can say it better, and I sure don't want to say any more when a video is available.

In this blog post I want to highlight a great little ten minute video that I recommend for any engineer that now or ever has had the need to figure out how to determine the level of a material in a vessel.  The video is titled "Back to Basics: Basics of Level Measurement".  Walt Boyes is the editor of CONTROL magazine and a major asset to the publication, their website and the automation industry in general.  I can't say enough good about him.  He is brilliant in many areas of process measurement, control and automation, yet very down-to-earth and he cares about the industry and the people within the industry.  I am honored to name him a freind, one I don't see hardly enough anymore (Walt, how about lunch?).  Anyway.... take a few minutes and watch the video!

If you need to measure the level of a powder and bulk solid I have another more detailed resource for you.  Download this file for the white paper titled Continuous Level Measurement of Bulk Solids (or something close to that LOL).  Download whitepaper_tech_review_of_cont_level_for_pbs_apps.pdf

Joe Lewis

Technorati Tags: Ethanol level sensor level measurement basics bin level indicator level control solids level indicator guided wave radar 

Ethanol plants use a variety of level controls

Ethanol production is at an all-time high in the United States and around the world.  There is a huge amount of research on-going in the field as well to determine what else we can process to turn into a fuel source besides corn.  With the surge in gasoline prices this year a boost to Ethanol has occurred.  While some critics blame the Ethanol industry on increasing grain and food prices, this industry generates thousands of jobs and billions of dollars in the economy for construction and operation of these facilities.  Let's look at where level measurement and monitoring devices are used:

Corn storage silos: Typically using open-air radar or smart weight & cable systems.  Guided wave radar is also a possibility depending on range required.  High level overfill protection can be handled with self-validating rotary paddle technology.

Corn surge hoppers: Application for guided wave radar technology as range is usually less than 30' and atmosphere is very dusty.

Corn grind silos: These applications can also be handled with guided wave radar technology or even open-air radar.

Dryers:  Best fit with RF capacitance point level sensors for high and low level detection.

Many other applications exist and sensors required for measuring level are varied.  Open-air radar, ultrasonic, RF, rotary paddle and other technologies are used.  The manufacturers and contractors that thrive from the construction and operation of Ethanol facilities also benefit greatly from this industry.  Ethanol is good for the USA.  What to know more?  Click here for a Download WhitePaper_EthanolSolutions.pdf free white paper.

Joe Lewis

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Vegetable oil isn't too slipery for guided wave radar

Measuring a wide variety of crude vegetable oils can be a challenge for some continuous level measurement technologies, but it is an ideal application for guided wave radar.  In China crude vegetable oil is brought in by ship and stored in vessels by the Taixing Port Authority.  This port is in Jiangsu Province near Shanghai.  At this facility there are 11 vessels with crude vegetable oil and the port authority needed a reliable way to monitor oil inventories to ensure security and accurate transfer of the oil in and out of the vessels.  Ranges varied from 55 feet and above.

The crude oil is bought by local manufacturers and refined further.  Most oils at the port in this application include palm oil, olive oil and bean oil.  The dielectric constant of these oils are fairly low, around 1.7-1.8 so many technologies will be challenged to work consistently and accurately.  The solution to the measuring challenge came in the way of guided wave radar when a local instrumentation distributor, Conasen, recommended the sensors.  In this application the GWR sensors were outfitted with a RS485 digital communications output and the automation supplier connected this to a PC running inventory management software furnished by a local supplier.  All is working well!  Guided wave radar, good and reliable for liquids and solids as well.

Joe Lewis

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