level measurement

Vibratory Level Sensor and Heavier Dry Materials

        


Recently one of our Application Engineers was asked if a vibratory style level sensor could be used to detect heavier bulk solids materials such as metal shot blast media.

Our Application Engineer responded by mentioning that a vibratory type level detector can indeed be used to detect shot media.  However, due to the nature of the vibratory technology, this type of sensor would require a protective baffle to be installed if it is employed where heavier materials are stored or in a dynamic process where the material may be shifting en mass (see baffle examples above). Most designs for the vibratory type level detectors contain a sensing element, that if bent as a result of mishandling or exposure to excessive process dynamics the sensor can be rendered ineffective.  Of course, the heavier the target media the greater the chance of the sensing probe suffering damage.

Heavier powder & bulk solids materials like metal shot blasting media may be even better served by a bin level indicator which is more rugged.  Monitor's model MK-2 R.F. Capacitance level detector is recommended.  This instrument is designed with a sensing probe constructed of a solid T316 SS and even if deflected will continue operating.  It is very rugged.

 

For more detailed information on the best application uses for vibratory sensors, please check out our blog entitled How Many Figs does it take to Equal 150 Newtons?

DC powered rotary paddle level switch uses AC motor to ensure functional reliability and long operational life

Does your installation require low voltage (12 or 24vdc) and you still want the reliability that rotary paddle level indicators provide?  You don’t have to settle for a lesser rotary product… check out a practical solution that Monitor offers in their rotary paddle level indicator line.

Most manufacturers of rotary paddle indicators do not offer a highly-reliable 12 or 24vdc option. Monitor does. Monitor Technologies implemented a design change in the 12 and 24vdc rotary paddle bin monitors.  The change dramatically improved the performance of these models and made them a viable solution for process oriented systems requiring a low voltage power source, minimal installation cost, and frequent level cycling.

Rotary paddle bin level monitors use a small motor to rotate a paddle that protrudes inside a silo or bin.  As material surrounds the paddle, its rotation is halted.  Within the bin monitor, the motor continues to rotate creating an internal cam action which actuates the output switch.  In addition, the motor is shut off through the actuation of a second switch within the bin monitor. 

Typically when specifying a rotary paddle bin level switch, the operating source of the sensor (115vac, 230vac, 24vdc, etc.) matches the operating requirements of the internal motor.  This results in AC powered bin monitors using AC motors, and DC powered bin monitors using DC motors.

Economical DC motors are not designed to run continuously, and therefore their use in rotary paddle indicators result in compromised longevity.  These motors use internal brushes and commutators which physically wear as the motor rotates.  Life expectancy is only 5,000 hours (e.g. six months of continuous operation) depending on application load and temperature. (Figure 1 shows a DC motor).                                                                    

Economical AC motors can be sourced that have a long operational life. The permanent magnet synchronous AC motor uses technology that has no physical wear characteristics.  Applications have operated successfully using this motor within the Monitor Model KA rotary paddle bin monitor for over 20 years.  (Figure 2 shows an AC motor).

The internal construction of Monitor’s 12/24vdc powered KA and KAX bin monitors is different.  Instead of compromising the design with a lower-life DC motor, the Monitor rotary paddle bin monitor includes electronics that converts the 12/24vdc power source to 6vac energy that is used to operate a 6v AC motor.  The Monitor 12/24vdc powered rotary paddle bin monitor is designed to save cost without the sacrifice of product performance and life expectancy.

So if you’ve been inconvenienced by poor performing low voltage rotary paddle indicators, or you’ve been told that all low voltage systems will work equally well, buyer beware!  Look into Monitor’s practical 12/24vdc solution and rest well.

Visit www.monitortech.com or contact one of our Application Engineers at fred@monitortech.com.

 Figure 1

 



 Figure 2

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

The day the sky darkened...a broken bag detector story

                   

The following diatribe or rant is a dramatization, the names have been changed to protect the innocent...

Friday started off as any other day, only a bit better than most days because it was a Friday!  Things at the plant had been running smooth, business seemed to be improving and we all hoped "free parking" in the company lot would soon be reinstated. Three dollars a day to park in the company lot seemed fair at first but after a while it all adds up!

All systems were purring along, in fact things were going well, perhaps too well.  Many routine maintenance "tasks" had been put on the back burner due to some staff reductions.  Sadly one of the easiest PM chores to ignore had to do with checking the filters in our baghouse.  No one ever really wants to climb up on the roof unless of course it is July 4th!

Little did we know that a small tear had began in one of the bag filters. Steadily the bag filter leak grew larger and larger allowing more dust to escape from the broken bag.  The weakened bag filter continued to fail, more dust was escaping. It was almost as if the dust wanted to run away from the bag house that had held it captive.

Suddenly a failure of catastrophic proportion occurred, a domino effect caused by air flow, dust, and failing bags, raged through the baghouse.  Only one small bag remained intact to prevent all of the dust from exploding into the atmosphere. Quickly, under the extraordinary amount of pressure and debris, the last bag filter gave way.  A cloud of dust roared from the bag house in a menacing swirl of darkness, temporarily darkening the sky over the "pay to park" company lot.

Alright, I am no Stephen King...but a situation like this could occur if you have a filter failure in a baghouse.  One of the best ways to monitor particulate emissions is to install a simple device designed to detect broken bags in a dust collector before a catastrophic failure occurs. 

Monitor offers a product we call the DustAlarm.  The DustAlarm is a broken bag detector, or a triboelectric particle emission monitor, the DustAlarm is designed to notify you when the amount of dust in the air flow begins to increase due to a pending filter failure.

The DustAlarm broken bag detector provides reliable and economical detection of leaks and filter failures in many powder and bulk solid industries.  As mentioned, the DustAlarm is a triboelectric particle emission monitor.  Triboelectric measurement has been used for years for broken bag detection, the phenomenon, also called "particle impingement" or "frictional electrification" pertains to the resulting charge transfer when one material rubs or impacts another.  The result of a dust particle collision with a stainless steel probe is the generation of electrical signals which are continuously monitored and analyzed by the electronics.  When the signal exceeds a preset level (such as what occurs when a bag begins to fail), a time delay is initialized.  If the signal remains above the preset level for the duration of the delay, alarm relay outputs are "energized".  These relays can be used to go to an alarm or to shut down your system to allow you to inspect your bag filters and determine which filter is beginning to fail.

For more information on the DustAlarm please refer to sales bulletin # 723.  If you have any questions concerning your application please give us a call.  One of our application engineers can work with you to make sure that the DustAlarm will help prevent the sky's above you from growing dark!

Best regards,

Scott Bonine

Director of Sales

Affordable Bin Aeration-You can leave the hammer at home!

Have you ever looked near the discharge area of a silo or hopper?  Have you ever noticed how banged up this area often looks? Have you ever seen a hammer located nearby? My guess is that we have all seen evidence where someone has severely beat the discharge area of a silo or hopper with a large blunt object to help empty the silo. Admittedly, I enjoy beating things with a hammer as much as the next guy but I would prefer to keep this hobby reserved for home "repair" projects.

In addition to several different types of remarkable level controls, Monitor also offers products to help fluidize materials so they will discharge freely from the vessel.  One of the most popular items we provide to assist in the flow of dry bulk powders from storage vessels is the rectangular air pad. The air pad operates by introducing air into the body of dry powder, this action fluidizes the material once it has "settled" after the target material was initially conveyed into the vessel. For best results multiple rows of air pads are often used depending on the vessel size and the bulk density of the target material  The number of rows and quantities will differ by each application.  One of our application engineers can assist by recommending a possible air pad solution for your specific material flow problem.

Air pads are very affordable and simple to install, different materials of construction and diffuser material are available depending on the application. The Monitor air pad can easily install in existing cut outs of other brands. Air supply requirements are minimal, typically 3-5 PSI.

Please give us a call to discuss your application, typical applications include but are not limited to:

• CEMENT  
• FLY ASH
• CARBON BLACK
• BENTONITE
• LIME
• GYPSUM
• FLOUR

We look forward to hearing from you.

Best regards,

Scott Bonine
Director of Sales
www.monitortech.com

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

Tired of the mystery?

I am not referring to Sherlock Holmes, or even the 2010 Cubs season…  I am referring to the mystery involving how much material do you have in your silo, bin, or hopper.

How often when you are filling or emptying a vessel do you have to ask yourself “Do I have enough room to add more material?” or “Am I starting to run low?”

A simple way to solve the mystery would be to install a level control. 

Monitor offers many different level control technologies designed to let you know “How much material do I have” or “Where is the level at?”

Some of the questions one should consider before looking for additional information would be:


- Do I need to know where my material level is at “continuously” or can I get by with just knowing when my material reaches a “high level” or a “low level” point in the vessel?  Examples of continuous level sensors are guided wave radar and smart weight & cable based (plumb bob).  Examples of point level controls include rotary paddle, rf capacitance, vibratory, diaphragm pressure switch and tilt switch.

- Do I want something that is an all electrical device with no moving parts (Ex. guided wave radar, rf capacitance) or would something electro-mechanical suffice (Ex. cable based, rotary paddle)?

- Do I want the “top of the line” (Ex. guided wave radar) or is price point more of an issue (Ex. rotary paddle, diaphragm pressure switch)?

- Are there any “extreme” conditions with the application? High Temperatures, Chemical Compatibility, or Vibration?

- Do I want a level control that is “fail-safe”, one that is capable of monitoring its own health so I am notified in the event of a problem (Ex. SafePoint rotary paddle, MK-2 rf capacitance)?  "Fail-safe" units are prudent in critical applications where you always want to be sure the level control is working.


These are only a few of the questions that you may want to ask yourself if you have grown weary of the mystery concerning your material levels.

I encourage you to call one of our tech support “gurus” to discuss your application. They can give you product suggestions based on your needs and will provide you with a practical solution at every level.

Additional information on any of our products can be found easily on our website - www.monitortech.com.

Scott Bonine

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

Affordable, practical solutions in level measurement

 

Although business activity levels are beginning to show signs of improvement, many customers are still looking for affordable and practical solutions for their bin level control needs.

Monitor is pleased to be able to offer a wide range of products at a variety of price points to satisfy every budget. Many around the $200.00 range.

Certainly one of the most successful technologies ever devised for point level control is the rotary paddle bin level indicator.

Rotary paddle units are almost legendary for offering a near perfect balance of price and performance.  Monitor offers our standard KA rotary paddle level indicator for less than $200.00. This is truly a bargain especially when you consider all you get for your money.  The KA offers a time tested simple electro-mechanical design, a rugged cast aluminum powder coat finished housing, as well as, an industry leading motor shut-off feature.

Another product worthy of consideration in applications requiring a compact and affordable solution is the proximity switch. 

Monitor offers two versions, the PAC-30U and the PDC-30.  Both are capable of sensing liquids or solids, conductive or non-conductive materials, in contact with material or non-contact. Monitor's proximity switches are solid-state devices providing solid-state outputs designed to provide years of maintenance free operation. Both models are available for less than $200.00.

In addition to the KA rotary paddle unit and the proximity switches, Monitor also offers pressure-sensitive diaphragm switches and tilt switches. 

The Binatrol pressure-sensitive diaphragm bin level monitor offers low-profile mounting, multiple diaphragm materials to handle most powder and bulk solid applications, and "green" operation with no power consumption.  Diaphragm switches have been used successfully in many industries for decades and they continue to be used as an affordable solution by customers world-wide. Most of our diaphragm switches are available for less than $200.00

The tilt switch offers a design some believe was inspired by the leaning tower of Pisa.  The switch tilts 17 degrees and a steel ball centered on a switch "rolls off center" deactivating the switch.  This is an environmentally safe product with a mercury free switch design that has often been imitated but never duplicated by the competition. The standard model TC-3 is available for just a bit over $100.00.

More details on any of these fine and affordable practical solutions are available on the Monitor Technologies website: www.monitortech.com

Feel free to call one of our application engineers or technical support people to discuss your application and see if one of these money saving products can solve your level control needs.

Best regards,

Scott Bonine

Director of Sales

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

You light up my life...

It has been a while since I quoted Debbie Boone...a long while. In a way I am somewhat relieved by that fact!

I am not talking about finding "hope to carry on" but I am talking about a light that may have some value to you and your process. The light I am referring to is the light available on a couple of our products. Our SafePoint  Self-Validating Rotary Paddle Bin Indicator and our MK-2/MK-2e RF Capacitance probes are provided with a high intensity LED indicator on the housing (ordinary location approvals only). This highly visible light will let you know at a glance the status of the relay, you will easily be able to determine material presence or absence based on the light color.  If the sensors are installed in an area visible to your operators this light can save you a huge amount of money by eliminating the need for an external light and the need to have an expensive electrician wire up the external light.

The light on the SafePoint Rotary Paddle Bin Indicator is also used to let you know when the sensor is is having either an electrical or mechanical malfunction. The SafePoint is a true "fail-safe" device that constantly monitors its own "health", in the event of any problem you will be notified that the sensor is not working! The true "fail-safe" feature of the SafePoint is of great benefit in critical applications when you need to know your level control is operating properly. Please give us a call to discuss any of your level control needs. Additional information on any of our products can be found easily on our website - www.monitortech.com.

Scott Bonine
Director of Sales

Technorati Tags: Level measurement basics 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

Moving SiloTrack Inventory Management Software from one PC to another

If it is time to up-grade your PC this brief will help you manage the re-installation of the SiloTrack inventory management program. A SiloTrack installation actually consists of hardware and software.  When moving SiloTrack to a different PC the hardware must also be moved.

SiloTrack consists of:
> Interface hardware which is the RS-485 communication converter/adapter
> Security Key hardware
> Application software; “The SiloTrack Server Program"
> Data files

The interface hardware device allows the SiloPatrol sensor(s) to communicate with the PC.  Older systems utilized an internal PCI serial card RS-485 adapter.  Newer systems use an external USB to RS-485 converter ‘box’/adapter. Simply uninstall the hardware from the old PC and prepare to install it on the new one.  In all cases the drivers for the interface device will need to be installed onto the new PC before the hardware is physically installed/connected.
 
Remove the security key from the old PC. The older SiloTrack system utilized security key fit to the PC’s parallel port .  This small device has the appearance of a pass-through connector or gender change adapter. It will have to be physically moved to the new PC. In the event the new PC does not have a parallel port we do have a USB solution.  Please contact Monitor if necessary.
 
First, install the Sealevel drivers for the RS-485 converter/adapter for your particular model.
Next, run the SiloTrack Server installation CD. 
Follow the Set Up Wizard to complete the installation if you wish to start over as if you were a first time user.
However, you can avoid needing to reprogram all of your silo dimensional information and other operational parameters by copying the following files from your old PC into the working SiloTrack directory of your new PC and into the C:/backup directory:
silotrack3.mdb and silotrackdata.st3

Andy

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