level measurement

Using flexible extensions with bin level sensors

Using extensions on level sensors that are used to monitor high level conditions in bins and silos is not new.  Many applications exist where the shaft is extended up to 12' from the mounting point of the level sensor.  These situations are when the senbsor is mounted on the top of the vessel, not the side.  However, sometimes the length of the extension, the type of material and its flow characteristics are such that the side loading caused by material flow and movement can be damaging to the sensor.  In these situations a "flexible" cable extension is desired to be used.  We recommend these flexaible extensions for use with rotary paddle type bin level sensors up to several feet, however, we are aware of customers using longer lengths.  The real limit on the length has to do with actuation time due to the rotation of the sensor output shaft and the twisting of the cable.  Up to six or so feet will provide reliable actuation of the sensor.

Next time you need an extensions for your rotary paddle bin level sensor for high level control consider a flexible extension.  The length is even easily modified in the field.

Joe Lewis

Technorati Tags: silo spill silo overfilling silo overfill prevention fail safe level sensor self validating level sensor high level sensor level sensor extension

Dust can be a problem when adding Computer Hardware

Recently I flew to San Antonio to resolve an issue where an RS-485 Flexar unit absolutely would not communicate with a recently installed RS-485 PCI Bus adapter.  In this case, the computer recognized the card and drivers to be installed correctly because there were no errors reported when the hardware was examined in Control Panel of a PC running XP-Pro Service Pack 2.

After climbing the silo, examining all the wiring and soldered connections, verifying the sensor was functional at the process connection, I was ready to pull my hair out (It's OK, I have a lot for a man of my age).  I had taken my laptop and a USB RS-485 converter with me.  As soon as I plugged the customer's communicaion cable into my computer equipment, I had instant and reliable communications established. 

Since the above actions isolated the problem to the customer's PC, we took the covers off and moved the PC to a different slot. In doing so, I could feel the grit on the electronic connections as I pulled the board out. To make a long story short, I took a deep breath and blew what I could out of the PCI Bus connector on the pc, re-installed the RS-485 adapter, and upon power up established a successfull communication link between sensor and PC. Obviously, dust and dirt can be a good electrical insulator.

So, if you ever install computer hardware in a PC that has resided in a dusty/dirty environment for some time, I would consider taking the CPU outside and blowing it out with compressed air before performing the hardware installation. So, Concrete batch plants - take notice. :)

As a side note, there are industrial grade PC's on the market that are well sealed and cooling air is well filtered. They cost typically 4 to 5 times more then a generic pc at your local super store but may indeed be worth the price to you.  However, filters require periodic maintenance. Food for thought.

Greg DeRudder

Technorati Tags: silo spill silo overfilling silo overfill prevention fail safe level sensor self validating level sensor silo inventory management sensor computer systems 

Getting the Most out of that Expensive Service Visit.

Having a factory technician visit your facility for non-warranty service can be expensive.  After years of conducting field service visits, here are a few few tips I'd like to offer to help get the most from this expensive eventuality.  Yes, some of these tips may seem obvious but sometimes these things just have to be mentioned.

A)  Provide a listing of the equipment to be serviced.  OK, this tells us what parts may be needed - or if the equipment is even serviceable.  Providing no information leads to assumptions, the results which can be unpleasant.

B)  Provide a description of the problem experienced.  It'd be a shame to spend mucho molla only to hear that the problem is not a result of, or directly related to, the suspected piece of equipment being serviced.

C) Show up for work the day of the scheduled service visit.  No joke, it happens all too often that I have traveled to a job site to service a piece of equipment only to find that my site contact has taken the day off. The service activity will proceed but it's now up to the service tech to define the problem.

D)  Assign a responsible person to work with the technician.  Sort of related to item C above.  This facilitates communication and insures that the servicing proceeds at an efficient pace.  Often is is necessary for the tech to access other equipment and a company agent can provide direction and help mitigate any process disruptions.  Additionally, training/guidance as to the routine or periodic maintenance issues can be transfered which just might eliminate the need for future visits.

E)  Be available for a review-of-service briefing.  Hey, a bunch of money was just spent - don't you want to know how and why?  Also, a review of the work completed can insure the original problem was indeed remedied.

Andy Bowman

Technorati Tags: silo spill silo overfilling silo overfill prevention fail safe level sensor self validating level sensor instrument field service

Hello, Is This Thing On?

So, you show up at work and that expensive computer gadget or new process sensor isn't working.

Before diving deep into computer settings, network switches, set-up routines, etc... check the very basics; is it plugged in?  This most basic of troubleshooting steps will solve a surprising number of problems.  We once had a ultrasonic continuous level sesnor that was behaving erratically.  Sometimes it would be working fine and then all of a sudden stop working, then it would start again and so-on.  We discovered after a service visit that the power to the sensor was wired through a light switch!

But wait, the device is plugged in.  So what is the state of the electrical circuit to which the plug is connected.  Connection to an inadequate electrical service will stop the best design gadgets in their tracks.  Is the light switch turned on?  Ha Ha... true story (see note in previous paragraph). 

Check the power before proceeding with other troubleshooting.  Any electronic sensor which has been installed on a switchable circuit (recommended as a good practice) is certainly subject to this possible problem.  You may just find that this is surprisingly common.

Andy Bowman

Technorati Tags: silo spill silo overfilling silo overfill prevention fail safe level sensor self validating level sensor

Does Stainless Steel Rust?

If you have ever paid extra money to have an item made from stainless steel only to be shocked to to see it develop that unsightly red-orange surface rust, this bit of information may be of interest to you.

No, chances are you were not sold inferior material.  Rather the item was most likely just inappropriately handled.  Even the most corrosion resistant grade stainless steel can see red-orange iron oxide visited upon it if handled without adequate care.

The tell-tail red-orange iron oxide most likely developed as a result of what engineers call "environmental contamination".  This is to say that some post-casting processes deposited the demon iron ions onto the surface of the stainless steel.  Of course as the item is exposed to moisture the iron contaminate oxidizes into red-orange rust.  Ick!

Now where does this iron contamination come from?  The answer is that it comes from just about everywhere.  Any machining tool, file, grinding wheel, abrasive belt, etc... can contribute.  If the grinding wheel used to sharpen a chisel yesterday is today grinding the casting seam of the stainless steel item, then all sorts of iron particles from yesterdays work will be transfered onto the surface of the new work piece.  Wire brushes and cleaning pads are also common contributors.  By the way, the worst thing you can use to clean your expensive stainless steel refrigerator, range, dishwasher or microwave is "steel wool".   Scouring with "steel wool" will embed iron ions from the itself into the grain of the stainless steel.  Slowly the iron will oxidize and the finish will dull into an ugly mottled dingie brown haze.  Ick!

So, how do we prevent such contamination?  One way is to make sure the tooling used for stainless steel is kept separate from tooling used for iron or other materials.  If tooling and handling cannot be segregated the item can be treated after processing to remove the rouge iron particles.

The after-process treatment is called "passivating".  An excellent article regarding this can be read here Download Definition-PassivationProcess.pdf .

Andy Bowman

Technorati Tags: stainless steel bin aeration

Volume Calculations for Horizontal Laying Tanks

Every now and then I get a call from someone asking how to calculate the volume of a horizontal laying tank with dished or dome ends.

The first time I needed this information, I literally spent a couple of days searching for a solution that was not going to cost me a fortune in new reference books or computer software. Out of despiration, I posted my need on the Water and Wastwater Dot Com  http://www.waterandwastewater.com/ help forum. One of the reqular contributors of this site was kind enough to direct me to the Chemical Engineer's Handbook of which we had a copy of in our Engineering Library. There I found data that allowed me to calculate the volume for any level in the tank I was working with thereby ending the frustration that I experienced while searching for a solution. Said data includes information for ASME dished ends.

Greg DeRudder

Technorati Tags: horizontal tanks volume calculations tanks level sensor

When everything old is new again!

I was on a recent  sales call with Ed Papenhause, the Monitor representative who covers the great state of Wisconsin (the entire state is now in mourning after Brett's retirement, long live #4).  The customer, Flambeau Plastics does injection and blow molding.

We were demonstrating two different technologies, the SiloPatrol and the Flexar, to replace some 20 year old Monitor CM3A weight and cable systems.  The CM3A system has performed faithfully but many replacement parts are now obsolete.  After considering the pro's and con's of both of the systems the folks at Flambeau decided to purchase new SiloPatrol units along with our SiloTrack software.

The customer based his decision on several factors:
1. how often do they need to do a reading,
2. price,
3. but more importantly what worked for them in the past. 

They knew that the CM3A weight & cable inventory monitoring system worked great and lasted many years and they were able to appreciate the design changes that make the SiloPatrol SE an even better unit.

I am glad to see repeat business, even at twenty year intervals. The quality and reputation of rep and product made this an easy choice for the customer and I am confident that their new system will be around for a long time to come.

If we can help you upgrade your existing system give us a call, we can make everything old new again!  For more opinion on this same subject take a look at the column in the March issue of Processing magazine.

Scott Bonine

Technorati Tags: inventory management Weight & Cable Upgrading Inventory Monitors level sensor

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

Silo spills can be avoided ........

The cost of overfilling your silo due to an unknown level sensor failure can be substantial.  I have blogged about this before but I still see people buying level sensors that have no way of telling you whether they are capable of functioning or not.  Lost material, damaged equipment, cleanup, air quality fines and lost production costs can add up quickly.  Take a look at this video, it's dramatic and illustrates exactly what overfilling a silo is like.  Then I'll tell you once again how to avoid this.  Enjoy!

   

How can you keep this from happening?  First understand that one reason that this situation can occur is a failed high level sensor.  Most filling systems use the high level device as a way to stop the filling.  However, most sensors used do not have any way to tell you if they are able to perform their function or not.  This is why I always recommend a self-validating point level sensor.  Self-validating point level sensors are continuously monitoring their internal functions to be able to tell you whether they can do their job or not.  They provide an output separate from the material sense output to indicate that they are either healthy or they have failed.  By monitoring the "health" status output you find out immediately when the unit fails.  Don't wait, change to a self-validating point level sensor today and make sure the above overfill disaster doesn't happen to you.

The cost adder for a self-validating point level sensor?  About $100 US.  Keeping the above disaster video from becoming a reality for you?  PRICELESS!

Joe Lewis

Technorati Tags: silo spill silo overfilling silo overfill prevention fail safe level sensor self validating level sensor

Do not overlook the simple things when troubleshooting an installation that worked for years.

I have been in touch with a customer that installed our first generation SMU over 2.5 years ago.  Read the email threads and see for yourself what steps constitute a typical diagnostic and troubleshooting procedure for a simple RS-485 network with multiple sensors. I will have a final comment at the end of this post, but this case history actually speaks for itself. Procedures outlined in this post generally apply to both SiloPatrol and Flexar with very minor exceptions, the most significant being that the Flexar guided wave radar line does not have a built in network termination resistor on the RS-485 module which changes one of the outlined procedures, unless the installer added one during installation. These threads have been slightly edited for clarity and condensation of text.

Greg

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CUSTOMER SUPPORT INQUIRY:

"Greg,

Our SiloTrack Server has been running great for 2.5 years, and then suddenly, Com errors appeared on all 4 SMU's.

I went up on top of the silos and verified that the SMU's have power, and that I can run them in Manual mode, using the push buttons on the SMU circuit board, and it all works just fine.

Then I purchased a new RS 485 Serial Card, set the jumpers just like the old card, and installed it into the SiloTrack Server -- but it won't see the SMU's on the network.

I suspected wiring at one point, so I disconnected all devices except for 1 of the SMU's and the SiloTrack Server Computer, and even this did not work to re-establish communications.

My next step will be to get 100-foot of new wire, and wire the Server to one of the SMU's directly, bypassing the old wiring.  But I am doubtful that even this will work, because I suspect that something may be wrong with all 4 silo SMU's.

My questions:
1.Is there a way that I can test communications on each SMU individually, to verify that their COMS are working independently of the SiloTrack Server, and network ?

2.Is there a way that I can test the RS-485 board from SeaLevel to verify it is working?

Thanks,

Valued Customer"

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TECH SUPPORT RESPONSE

"Dear Valued Customer,
 
The fact that you are getting a COM error indicates to me that the PC is seeing the RS-485 card as a valid com port. This does not mean, however, that it is indeed fully functional but the likelihood is very high. 
 
Usually when someone gives me a similar report as you have, it is a simple matter that someone killed the power circuit breakers to the SMU's. If not, cycle the power to the SMU's and you will effectively reset the sensors without climbing.
 
The next thing I would do is power off all of the SMU sensors and remove the DB9 connector for the RS-485 bus from the PC. With an ohm meter, measure the resistance between pins 1 and 2.  If your termination switches are correctly set, you should see around 100 ohms. If you measure a very high resistance or infinity, either no termination resistor is on or you have an open circuit on your communication line. If you measure a low resistance, you likely have a short somewhere or have too many termination resistors enabled.
 
Now, on the PC side, go to Control Panel, Device Manager, Hardware and check the PCI card entry for errors. Verify that the virtual com ports assigned to the RS-485 adapter are indeed the same as you have configured in SiloTrack under CONFIG, Networks of the Task bar.  If you restore the jumper settings to the Sealevel factory default, you can run the WinSSD diagnostic on both serial ports. Sealevel factory settings have the card running in RS-232 mode. The instructions for this test are contained on the Sealevel Installation CD.  First, a loop-back connector must be constructed by obtaining a DB9F connector and shunting (jumper) pins (1 & 4) and (2 & 3). The BERT test contained on the Sealevel CD verifies two way communications. Since you have tried two separate RS-485 cards, if the test does not work, I would un-install the sealevel software, power off the PC, remove the Sealevel Adapter card from the PC, power up the PC, reinstall the Sealevel drivers, power down, re-install the sealevel card in a different PCI slot (Don't forget to return the jumpers to RS-485 if the test passes), and repeat the test.

The last test I would do before pulling new wire would be to remove one electronic module and the power connector from one of the sensors. Construct a new short cable with a DB-9F connector with the wires connected to pins 1 & 2. Do not connect the shield to pin 5. Secure a line cord with plug to the power connector. Connect the DB9 to one of the serial RS-485 ports and apply AC power to the module taking care not to allow any shorts or allow yourself to touch the modure anywhere while the module is powered so you do not get shocked. Prior to applying AC power, be certain that the address switch on the module is a valid setting for one of the silo icons configured for that particular port.  If the ICON on the PC screen says READY, you indeed have a wiring problem. If this does not happen, send us the Module for evaluation.
 
Keep me advised of your findings.
 
Thanks,
 
Greg DeRudder,
Technical Sales Support Manager"

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FURTHER CUSTOMER COMMENTS REGARDING PROBLEM:

"Greg,

Long story short -- a "Cold Solder Joint" was found in the DB9 cable going into the SeaLevel 7201 RS-485 card.

When IT came out to swap the monitor, they must have tugged on the SiloTrack 3-wire cable, and loosened one of the soldered wires.

We re-soldered it, and now the network is communicating with the SMU's.

Thanks for the help,

Valued Customer"

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TECH SUPPORT COMMENTS:

"Final Comments

Depending upon the quality and type of solder you use, connecting your communications cable to the DB9F connector can range from “A piece of cake” to a “Pain in the @$$.” A good clean tin-lead Sn63 solder with a sufficient quantity of resin flux will leave a very smooth and very shiny solder joint that is easy to inspect. Solder that is not pure (the really cheap stuff) will harden as it cools below the melting point sometimes leaving a dull pitted looking appearance. (see photo)  After stripping the insulation to the correct length, I prefer to tin my RS-485 wires before inserting them into the DB9F for final soldering. This step greatly reduces the risk of having a poorly soldered joint and it is well worth the effort. If you typically apply additional flux to your joints (I’ll leave this alone at this point, but the quotation “I did not inhale” does come to mind), you should also have the appropriate solvent to remove and residual flux residue. This results in a much higher quality of soldered joint that is easily inspected.Also, watch the temperature of your soldering iron. You don't want it to get too hot or you will have other issues to deal with. Your iron should be just hot enough to allow a smooth yet gentle reflow of the solder between the two pieces being joined. If the solder and flux "spits" at you, it is probably too hot.

What about RoHS you ask? We will try to cover that subject in a future post once compliant solders and effective fluxes become more readily available and are more commonly used."