level measurement

Auxiliary Output Enclosure (AOE) Satisfies Input Needs for other Plant Systems

  

When choosing a continuous level measurement system, in addition to an operator interface, sometimes a customer also wants to have an output to some other type of control system such as a PLC or DCS. Available outputs include both relay contacts and analog outputs.  To fulfill these requirements, Monitor developed an auxiliary output enclosure (AOE) capable of housing as many as four output cards containing either relay outputs, analog outputs or a combination of both. When controlled by our HMI2 operator interface, each SiloPatrol® SMUse level sensor can drive one analog and up to two relay outputs. If SiloTrack Inventory Management Software is the operator interface, the number of analog outputs assignable remains at one analog output per sensor but there can be up to four relay outputs per sensor. RS-485 communication wiring consists of a twisted pair that is shielded and installed in a daisy chain fashion. Since the auxiliary output enclosure is also an RS-485 driven device, the AOE can be placed anywhere along the RS-485 communication network. Placement of the AOE in close proximity to a PLC or DCS reduces the amount of additional wiring necessary to connect the AOE outputs to the inputs of these other devices. This will significantly reduce the amount of interface wiring that would normally be required by standard analog output sensor wiring practices.

Flexar® guided wave radar level sensors that are used in conjunction with SiloTrack Inventory Management Software can also drive an auxiliary output enclosure as previously described.

Auxiliary output enclosures are available in either two or four output card configurations. (Two card version shown above.)  The two types of output cards can be mixed or matched. Flexar® guided wave radar and SiloPatrol® SMUse sensors may not currently coexist on the same RS-485 communication network. Consult Monitor's Technical Support group for selection of the correct SiloTrack product offering if your over-all sensor system design requires the use of both SiloPatrol SMUse and Flexar guided wave radar sensors.

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

How Many Figs does it take to Equal 150 Newtons?

Vibratory point-level sensors or probes are great products for powder and bulk solids applications where the material being sensed has a very low dielectric constant that might be lower than an RF Capacitance probe could detect. They are also good alternatives for rotary paddle bin indicators in application with extremely low bulk density values. Expanded poly-styrene beads have a bulk density that is typically less than 2 lbs/ft³ (.032g/cm³). Paddle type sensors and especially high level paddle type sensors would very likely cavitate when covered with material this light and give no indication that material is indeed present. 

 

What if we have an application for a bin whose material frequently changes and we were using a rotary paddle bin indicator?  If the bulk density decreases, at some point the paddle being used will start to cavitate and a paddle with a higher surface area (increasing the effective sensitivity) would need to be installed to allow the paddle type sensor to regain functionality. There will be a lower limit of bulk density vs. area of the paddle that once reached will ultimately render the paddle type sensor useless for the application in question.  If an RF Capacitance probe is being used in silos, hoppers or bins and the material is changed to something with a radically different dielectric constant, probe recalibration might be required. This is where a vibratory probe is a great choice because there is no calibration per se. Many vibratory probes on the market do have a general sensitivity setting that can be changed but that is an adjustment the rarely needs to be set differently than the factory default.

 

The main downside of a vibratory probe is that it is generally more expensive than a paddle or RF Capacitance type of sensor. Another negative feature of a vibratory probe, and main point of this article, is that models that are high in sensitivity and able to detect materials with very low bulk densities are typically not as physically strong in comparison to other point level technologies. So when we use a vibratory probe, we must strictly adhere to the manufacturer's installation guidelines.

 

According to a conversion website I frequent:

150 Newtons = 33.7 pound-force.

500 Newtons = 112.4 pound-force.

1000 Newtons = 224.8 pound-force.

"So what?” you exclaim.

 

One of the most common reasons for vibratory probe failure is from the probe having been subjected to forces beyond their design limitations. Such a condition can actually bend the probe rendering it useless. Other modes of failure include broken components within the probe housing or within the probe element if it is a rod type or diamond shaped design.

Below are examples of parameters for vibratory probes.

 

PZP PROBE LIMITS

  

OK, here come the Newtons.  Our model PZP has two separate force limitations. The probe must be installed such that the narrow edge (knife edge if you will) of the probe is always pointing up. The PZP can withstand 1000 Newtons max in this plane but will only withstand a maximum fore of 150 Newtons along and perpendicular to the axis on the wide side of the probe.  Our VibraRod probe is constructed using a hollow tube that is cylindrical shape and is rated at 500 Newtons max in any plane along and perpendicular to the axis. 

 

Generally speaking, either probe should be shielded from direct impact from material falling directly on the probe during the filling process depending upon material characteristics. There are suggestions for doing so in our Installation & Operation Bulletins for these products.

 

So, when you need or want to use a vibratory probe, be mindful of all forces the probe will be exposed to during fill and also when material is being drawn out. How and where the probe is mounted to the vessel will have a direct influence on the amount of force the probe is subjected to when the material contained in the vessel is in a dynamic state. Mass flow silos and hoppers will produce more force against the probe than its funnel flow counterpart would exhibit. Properly placed baffles will correct this problem. Also determine if there will be any significant side or lateral horizontal loads that either require silo modification or require the selection of a different style of probe so ensure that maximum force specifications are never exceeded. If you find yourself needing or desiring a vibratory probe and you have determined a need to install protective baffles or shields but you are unable to install them, you should consider using a top mounted cable extension model or a rigid pipe extension model. A cable extended probe will allow the actual sensing portion of the probe to hang freely at the desired point of material detection without exceeding specified lateral force limitations. See examples below.

                              

VibraRod with cable extension   PZP with cable extension

 

Now if this seemed all too gloomy for you, relax.  We have many successful applications in materials with bulk densities as high as 100 lbs/ft³. You just need to think about the application and install the probe in such a manner that its limitations are not exceeded.  When in doubt, give our Technical Support department a call at 800-766-6486 for advice and guidance. We are here to assist you by providing practical solutions on and at every level we can.

 

Greg DeRudder

Product Manager

Monitor Technologies LLC

gderudder@monitortech.com

 

© 2010. All rights reserved.

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

Where do you get your product information?

In today's current economic condition, we have all found it necessary to seriously assess every potential expenditure and decide whether or not it is absolutely necessary. As Product Manager for Monitor, advertising expenses fall into my realm of responsibilities. In my previous position, I knew that the price of print advertising was high, but I did not know it was as expensive as it actually is. I realize print advertising is necessary and I have no intention of eliminating it at this time like one of my competitive colleagues is considering.  Consequently, I have reduced both the frequency and size of our printed ads and have put substantial effort into other resources that are not nearly as expensive and some actually have no relative cost at all.

Having said all of that, I would greatly appreciate a quick response from you telling me where you go or what media you use to research level measurement and level sensing equipment.

• Do you use magazines or other print media an if so, which?

• If you use the Internet, which search engine(s) do you use?

• Do you regularly participate in any Social Media sites such as Facebook, Twitter, etc?

• Do you rely upon Manufacturer Representatives or Distributors?

• Do you subscribe to Powderandbulk.com or similar site?

I look forward to your responses and I thank you for your time.

Greg DeRudder

Technorati Tags: Level measurement basics bin level indicator level control

Digital Cameras are a relatively inexpensive and indispensable diagnostic tool.

Those of us that have played the Tech Support Game for any length of time have at some point been in a situation where neither the caller seeking help nor the person trying to render assistance was understanding the other’s inability to comprehend what was being said or asked.  Believe me when I say that that is a situation that can turn volatile in a nano-second.  Especially in the level sensor business, there are some fairly creative ways for end users to improperly install point level sensors in a way that will severely impact the sensors ability to function as it was designed to do. Maybe we will work on a top ten list for later publication. Anyway, what I am doing on a more frequent basis is to ask the customer if they have a digital camera at their disposal. About now you are saying to yourself, “Self, almost everyone with a cell phone has a digital camera these days.”  While this may be true, my experience with the quality of the pictures taken and sent by a cell phone is that the pictures received are very often all but useless due to low resolution of the image.  Some of the newer cell phones have better resolution but there are going to be a large quantity of poor resolution camera phones out there for some time to come.  Almost any off the shelf digital camera is capable of providing the resolution needed to see intricate construction detail of some sensor mounting that was previously verbally obscure in the description of someone speaking a different mechanical language than the other person. When trying to photograph a sensor or sensor mount inside a dark silo, the low lux (low light) capabilities of most digital cameras indeed becomes a huge asset.

Innocent misunderstandings can change the tone of a conversation from friendly to confrontational in a very short time. No one wants that to happen and it can cause bridges to burn so to speak. So, if you find yourself in a situation when either receiving technical help or giving it and someone is not getting (ready for this?) “The Big Picture” (sorry, I couldn't resist J ), consider asking for or volunteer to take a digital picture and email it to the other party. A digital camera is a valuable tool and it can potentially reduce the amount of time it takes for a tech support person to identify a problem and offer a solution.  Best of all, a reasonably capable digital camera that is small enough to fit in a pocket can be quite inexpensive making it quite easy to justify obtaining one.

Take a look at the photo at the top of this blog post.  This photo happened to be taken by one of our service techs but it shows a bad installation for this guided wave radar sensor and explains why it wasn't working properly.  Never extend a nozzle into the silo when installing a guided wave radar level sensor.  The customer could have been talking to us for a long time before he stumbled on this little known fact because the installer and the person we speak with to provide tech support many times aren't the same people.  A picture is indeed priceless and worth more than a thousand words.

Greg DeRudder

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

Ethanol production is good for level measurement and good for the world.....

Ethanol production require a vast amount and variety of process measurement instrumentation as part of the overll automation and control of the plant processes.  For level measurement there are applications throughout the process from monitoring inventories of raw corn to helping to control dryers, to the monitoring of storage vessels containing the finished product.  But recently we have begun to hear in the media a number of comments talking about how bad Ethanol production is and has been.  It has increased the demand for corn and driven food prices up.  Well perhaps in the short term that is true but living out here in the corn belt of Illinois I can tell you that this country has more corn than you can imagine.  And, corn is not the only raw ingredient that Ethanol can be produced from, it is just the most common right now.

The point I want to make is in regards to the impact Ethanol production has on the world supply and cost of fuel.  I point to a study and report recently issued by LECG.  First, LECG (I have no idea what LECG stands for) is a "global expert services" firm.  They do studies and render expert opinions on a number of subjects.  Well, the Renewable Fuels Association had them do an impact study of Ethanol on the cost of crude oil.  That's right.  They answered the question "what would the impact be on crude oil prices today if Ethanol production did not exist?".  Well before I tell you what they found out let me tell you that they reported that the amount of Ethanol produced in the world in 2007 was 17 billion gallons.  The majority of this was produced in the USA and Brazil.  In 2008 it is projected that this production will increase by 20% to 20.4 billion gallons.

There appear to be complexities in calculating the impact of Ethanol on crude oil prices and I don't have the time, nor the patience, to dig into it and report it here for you, but the report by the LECG indicates that crude oil would cost another $35.70 per barrel if it weren't for the production of Ethanol.  Think about the effect of that on the price per gallon of gasoline next time you fill up and next time you drive by a corn field, or next time you hear someone talk down the Ethanol industry.

A complete editorial about the LECG report can be found written by editor Myke Feinman of Bieofuels Journal magazine.  The editorial appears on page 110 of the May/June 2008 issue.

Want to know more about the level measurement and monitoring applications in an Ethanol production operation?  Download this file.  It's a white paper on that subject. Download WhitePaper_EthanolSolutions.pdf   

Joe Lewis

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

Trade shows still work ......

Recently I had the opportunity and good fortune to be part of our exhibition at GEAPS.  This is the Grain Elevator And Processing Society.  We exhibited with a 10' x 10' space.  The GEAPS annual meeting is a great function.  Unlike other "trade shows" the GEAPS annual meeting is just that, a meeting.  The exposition part of it is just one part, and it really is great.  More valuable than leads from this exposition is the networking time spent with customers and potential customers, representatives, manufacturers and everyone that's anyone involved in these industries.  It reminded what it is like to be a part of a community and its a great one.

I just wanted to take minute here at the Level Measurement blog to thank everyone that administrates GEAPS and to thank all the members that attended this years meeting and exposition.  Thank you!  I look forward to seeing everyone at the 2009 meeting being held in St. Louis.

Thanks GEAPS!

Joe Lewis

Technorati Tags: GEAPS Powder Bulk Solids Show trade showslevel sensor level measurement

Election connection ..........

I am sure that many of you have grown weary of the election already, this one seems like it has been going on forever. 

The 24-hour media outlets do a good job of saturating us with constant updates concerning the front-runners and don't forget the latest celebrity endorsements.  Thanks to Oprah and Chuck Norris ...... if I cannot make up my own mind, a celebrity will be happy to do it for me. The worst is yet to come as we get closer to November!  For some help in seeing differences between the candidates, click here.

But this isn't really anything new.  The reason I wanted to post about the election is because of the effect that such things have on our economy.  A recent report from a market study company indicates that business investment plans dropped by 40% in January from December.  Many are brewing up a recession in their minds and all the talk doesn't help.  However, recently I have seen articles in trade publications like Concrete Producer February issue indicate and prognosticate that the recession fears are not going to come to fruiting. 
My question to you here is do you think that business will be influenced by the fact that this is an election year?  Are you expecting things in your business to pick up or slow down?

Please let me know your thoughts,

Scott Bonine
National Sales Manager
Monitor Technologies

Here we go again ...... wired or wireless, they seem to act the same

It seems like "dejavu".  In the last couple of decades of the 20th century the big giant process instrumentation companies did battle to see who was going to be able to drive the standards for communication protocols.  The big battles were between HART and Foundation Fieldbus that emanated out of the ISA SP50 committee.  If memory serves me, HART had become a defacto standard long before the SP50 was finished with their work and the first commercial products were available.  The fight between Emerson/Rosemount and Foxboro, Honeywell and others was a classic.... and the user was not served very well if you ask me.  There are still three primary field instrument communication standards, e.g. HART, Foundation Fieldbus and Profibus.   A recent research study reported that the first Fieldbus device was installed in 1997 and there are now almost 1.4 million Fieldbus devices installed around the world.  However, this pales by comparison to HART.  If you don't know how HART works, click here.

In his blog post from March 2007 Walt Boyes (editor of CONTROL magazine) estimated there were roughly 22 million HART devices installed.  He also puts the Fieldbus device total closer to 500 or600 thousand.  No matter, 22 million HART devices simply dominates the installed base of digitally connected devices.  Another third party study indicates that HART represents 71% of process instruments purchased each year in North America with digital connectivity.  It appears obvious that HART had become, and still is today, the defacto standard in wired digital protocols.  That's important to understand because for small process instrument companies with limited resources we can focus in on the development and marketing of a single digital protocol and provide a marketable device that will meet the needs of a vast majority of the market.  No matter how hard the HART opponents fought or how much money went into opposing HART, it is still the market leader.  It may be decades before it is replaced as the leader.  NO, I am not going to get into the argument of HART's disadvantages or advantages.  YES, I know it is not technically a "fieldbus", but I am not claiming it to be..... it provides digital connectivity for process instruments.

So, what's happening with wireless?  The same thing?  Maybe.  HART recently (September 7, 2007) formally announced the WirelessHART standard.  The attacks began before the formal release and intensified in trade publications.  However, check out the information about what WirelessHART can do at this web link.

The typical attacks against WirelessHART can be summed in the editorial written by Tim Bourke of Honeywell and published in the October/November issue of PETRO Industry News on pages 18 and 19.  The summary of conclusions is that 1) not all bus standards will run on WirelessHART and 2) there is no case where WirelessHART will work that the ISA100 standard will not.  Not a very convincing argument today for the small size process instrument company that can afford only a single implementation to drive and meet user demand. 

However, there is a possible difference between how the wired standards were developed and handled and how the wireless standards seem to be emerging.  At the recent ISA show last month it was decided, by HART foundation members and members of the ISA100 committee, that the ISA standard approach would work to integrate WirelessHART in its first release through a dual gateway architecture and then a more integrated approach in release 2.  Maybe the pundits on both sides will behave differently this time.  If so, the user will have a much better offering to look forward to.  Time will tell.  If not, we will likely see WirelessHART dominate the market of installed wireless connected instruments just as it does today for the wired digital connectivity.

Joe Lewis

Technorati Tags: wireless wireless HART wireless fieldbus ISA SP100

You Disappoint me....

No one likes to hear these three words, although there are several three-word combinations more disturbing, some examples are:

You are fired.
The IRS called.
Honey, I'm late.

But seriously, disappointing someone or being disappointed, is something we in sales deal with daily. Sometimes we are disappointed because we did not get the PO, or disappointed we could not see the "hallowed decision maker". 

In sales sometimes we are disappointing a customer because we cannot solve a problem for them, technical limitations, price, delivery, et- cetera, all may not fit into the customers plan or meet their level of expectation.

The key, in my opinion, to help minimize disappointment, is to properly manage levels of expectation.  I think this reigns supreme regardless of where we are at in the process.  If we as sales people can properly manage the customers level of expectation regarding product ability, lead times, or any of the other random hundred things out to get us we can hopefully avoid "disappointing" our customers.

With level controls, especially with inventory management systems, managing the customers level of expectation is huge!  Any device that measures "distance" and relies on a "calculation" to "convert" a "distance" reading into some other type of information must be properly managed early in the sales process.

How many times have we all provided a perfectly fine system for inventory management to a customer only to get a telephone call from someone in "purchasing" wondering why they are "off" by a few hundred pounds. 

Nothing fills a salesperson's bowels with ice water faster than a call like this! Now you find yourself re-explaining a technology and how a system operates, you are quickly knee-deep in doing damage control.  We all know that the salesperson's favorite non-profit hobby is doing damage control!

How much of this could have been avoided if only the customers level of expectation was better managed? I think we all would agree, that when a customer knows exactly what to expect calls are minimized.

My suggestion is to let us help you, we can work with you to hopefully manage the customers level of expectation and avoid disappointing someone.

Thanks,

Scott Bonine
National Sales Manager

Technorati Tags: sales management customer relations inventory monitoring

Back to the future of level measurement sensor placement

Hello, McFly! Is anybody in there?

Why is sensor selection usually the very last thing that gets considered when new silos are ordered. Having said that, many times level sensors are not even thought of until the silo has been erected on site. Then there is the "we will have to modify the silo to accommodate level sensors crisis".  Perhaps the silos were already cleaned and there is some material already being stored so cutting and welding is out of the question. Etc., etc., etc.

Too late for load cells and you didn't like the price tag anyway. So, I guess we will have to settle on a sensor that measures the empty air space and then calculates the volume and weight and make compromises to fabricate a process connection. Too often these days, I am seeing more and more new silo installations with fill points that are not in the center of the vessel. Every level measurement technology out there, except gravimetric, measures the distance (air space)between the sensor and a point of intersection on the material being measured. If the vessel is truly centerfilled and the level sensor is mounted at 1/6th the diameter from the outer wall on the radius, the calculated volume and or weight of the material will be very close to actual assuming all dimensional data and the bulk density data are accurate. Follow this link and download item 3 for complete details regarding sensor placement and accuracy of calculated volumes and weights: http://www.monitortech.com/wseminars.shtml  One word of caution is that some silo manufacturers consider center filled to be a fill point that is located anywhere within a circle defined as less than one-third of the radius. This is not good enough if you are striving to maximize the calculated accuracy.

Finally,remember to add an independent self-validating point level sensor to alert you when your silo is full and to prevent over-filling and potential spills, even those due to unknown sensor failure.  Refer to other posts within this blog.

Greg DeRudder

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