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

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

 

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

Monitor's MK2 RF Capacitance Bin Level Sensor Successful on Powdered Calcium

 

Yesterday I received a call from Ryan Dunlap of LECORP (I was proud to be partnered up with Ryan during a recent golf outing, many commented about our remarkable level of play, comments can be so cruel!).

LECORP is the Monitor representative group covering Kentucky, Tennessee, Southern Indiana, and Arkansas, their website is: www.LECORP.com, if you want to check out what else they offer.

Ryan began working with a plastic bag recycling company in December of 2007.

This company has used several different point level indicator products from a few different level control companies throughout their facility. They reported to Ryan that rotary paddle bin level indicators  and RF capacitance bin level probes manufactured by Monitor performed better than anything else they have tried. In fact they are so pleased with Monitor's products that they are replacing all other brands with Monitor!

A recent application for this company involved our model MK2 RF Capacitance Bin Level Sensors on powdered calcium and calcium coated pellets. The customer told Ryan that they were "tossing the other probes" and putting in Monitor on these applications because the MK2 worked great!

The Monitor MK2 is our top of the line RF Capacitance level probe featuring push button calibration, sensitivity selection and self-test features as well as amazing build-up immunity to ignore product build up that may cause false signaling with other probes on the market. More information on the MK2 can be found in the point level section of our website.

If you have a need to find a bin level indication solution in applications where other level products have struggled, give us a call, we may be able to help!

Thanks,

Scott Bonine

Director of Sales

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

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

Using extensions with rotary paddle level switches

Rotary paddle switches are a great way to detect when your material reaches or leaves a point in your silo. Frequently we see paddles being ordered with extensions, and occasionally, we see a significant length of extension. With an extension, you can mount your paddle switch in a top mount location, and ‘extend’ the paddle into the bin at just about any length (up to 144 inches), but when doing this; you have to take into consideration a few things.

The extensions are solid; they are subject to lateral forces that may end up doing damage to your paddle, the extension, or in few cases, the switch itself. This is why Monitor recommends the use of a guard, which surrounds the extension and prevents it from doing much traveling while in the vessel.

The use of our Springflex coupling is also highly recommended when the length of the insertion is greater than 18 inches. This takes a lot of lateral force off the paddle and extension by acting as a ‘shock absorber’ for the switch itself.

Also, keep in mind that the guard and extension, when ordering, are always going to be the same length, and with a guard, a full coupling mounting plate must be used. This will ensure that you get the most life out of your rotary paddle switch.

John Mish
Sales / Technical Support
Monitor Technologies

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

Affordable Reliability - Rotary paddle level indicator

 

In spite of all the different technologies available for point level detection sometimes there is no beating an old favorite. Rotary paddle bin level sensors have been used for years in all types of powder and bulk solid applications. 

Paddle units are still a best seller for Monitor and have been for our 50+ years of being in business.  50+ years is an impressive run for any technology so there must be something to be said about the humble paddle unit!

In addition to "ease of installation" and "reliability", the paddle unit gives a "great bang" for your buck!

Our standard model KA still sells for less than $200.00 for the power-pack. For critical applications, we also offer our SafePoint® rotary paddle bin indicator designed as a true "fail-safe" unit the SafePoint paddle unit will let you know if there is a problem either electrically or mechanically. The SafePoint is a bit more in price than the standard KA but the price difference is minimal when you look at what you get! The ordinary location SafePoint has a highly visible light on the cover so you can determine at a glance the relay  status.

Look, things are still tough for many of us, we are all looking for ways to get a job done as economically as possible without compromising quality and functionality. The next time you have a need for an affordable and reliable level sensor give us a call to discuss a KA or a SafePoint rotary paddle unit.

Scott Bonine

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