Choosing the Right Industrial Level Technology In Foaming Situations

In the chemical, manufacturing, food and beverage, life sciences, and other process industries, foam is sometimes a problem in liquid tanks. There is no "one-size-fits-all" level measurement option for foam because of its fluid nature. Understanding the properties of the foam and the type of measurement required is critical. Foam can form in a tank for various causes, including injecting air or gas into the liquid or agitator/mixing blade activity. Understanding the nature of the foam and the process is essential to minimize potentially costly errors when choosing a level measurement technique, regardless of the source.

For more information about applying the right instrumentation for level measurement in the presence of foam, contact Miller Energy, Inc.

In New York Metro and Northern NJ
Phone: 800-631-5454

In Eastern Pennsylvania and Delaware:
Phone: 610-363-6200

https://millerenergy.com

Critical Ethylene Level and Flow Application Brochure

In ethylene plants, balancing environment, health, and safety is essential while maximizing productivity.

Level and flow instrumentation will assist in preventing loss of primary containment and maintaining a safe environment inside of the tank. That’s critical, because incident consequences are significant, with the direct cost of a work-related death of $1M and indirect costs approximately 4 times greater. In addition, there is the lasting damage to your brand reputation and the compromised safety of the local community. Instrumentation can also assist in maximizing productivity, including interface type measurement in some of the harshest environments.

This brochure contains a wide spectrum of Magnetrol® and Orion Instruments® level and flow products that conform to the latest safety standards, including SIL requirements, to assist in the most critical applications in ethylene plants.

DOWNLOAD THE BROCHURE HERE

For more information about Magnetrol and Orion Instruments products contact Miller Energy, Inc. Call them at 800-631-5454 or visit their website at https://millerenergy.com.

Liquid Interface Level Measurement Using Guided Wave Radar, Magnetic Level Gauges, Float & Displacer, Thermal Dispersion, and RF Capacitance

The need for interface measurement arises whenever immiscible liquids - those incapable of mixing - reside within the same vessel. The lighter material rises to the top and the heavier material settles at the bottom. In oil production, for example, water or steam is used to extract oil from a well. Well fluids then route to production separators where they settle into their primary constituent parts as a water-hydrocarbon interface. Water may also be used as a transport medium or a cleaning agent and forms an interface with an allied material which is later extracted.

Knowing the position of a process interface is necessary for maintaining product quality and operations efficiency. The interface is measured and controlled by precision level switches and transmitters. Though at least 20 different types of liquid level measurement devices are in service today, only a very few are suitable for accurate and reliable interface measurement. Grouped by their operating technologies, these include Buoyancy (Floats and Displacers), RF Capacitance, Thermal Dispersion, Radar, and Redundant Technologies (those combining two measurement technologies in one instrument).

The five leading interface measurement technologies in use today are Guided Wave Radar, Magnetic Level Gauges, Float & Displacer, Thermal Dispersion, and RF Capacitance. These five leading interface measurement technologies in use today are discussed in the technical bulletin titled "Liquid Interface Level Measurement" and produced by Magnetrol International.

DOWNLOAD THE TECHNICAL PAPER HERE

For more information on any industrial level control application, contact Miller Energy. Call them at 800-631-5454 or visit their website at https://millerenergy.com.

Understanding Safety Integrity Level (SIL)

Nothing is more important than safety to the process control industries. High temperature and pressure, flammable and toxic materials are just some of the issues faced on a daily basis. Reliability is a key component of safety; the more reliable the device, the safer the critical process.

Safety integrity level (SIL) is defined as "relative level of risk-reduction provided by a safety function, or to specify a target level of risk reduction." SIL ratings are applied in accordance of frequency and the severity of the hazard. These ratings determine the level of performance required to achieve and maintain safety, as well as the probability of failure.

There are four SIL levels; SIL 1, SIL 2, SIL 3, and SIL 4. These SIL levels relate to the risk of failure - a higher the SIL rating poses a higher risk of failure, in turn requiring stricter safety requirements.

Magnetrol, a leading manufacturer of innovative level, flow and volume controls for the process industries has put together this excellent technical note to help you better understand Safety Integrity Level.

DOWNLOAD THE MAGNETROL TECHNICAL NOTE ON UNDERSTANDING SAFETY INTEGRITY LEVEL FROM THIS MILLER ENERGY WEB PAGE

Miller Energy, Inc.
https://millerenergy.com
800-631-5454

The Magnetrol Eclipse 700 Guided Wave Radar (GWR) Transmitter

The Magnetrol Eclipse® Model 700 GWR is designed with the chemical processing industry in mind. It gives you the performance and durability you need to address your biggest challenges in a streamlined, versatile configuration cost-effective enough to use in a variety of common applications.

The Eclipse® 700 is a guided wave radar (GWR) transmitter that easily handles challenging situations as well as common chemical processing applications. Its streamlined configuration gives you the features you want and the diagnostics you need, at the price point you expect.

Versatile – Able to be used in a broad range of chemical processing applications

Robust – Stands up to challenging conditions like foaming, interface, and high pressure or harsh conditions

Superior SNR – Strong signal strength is ideal for low dielectric media

Reliable – True Level Measure provides industry-leading accuracy along the entire probe length

Overfill-Safe Operation – Only Eclipse transmitters are available with overfill-capable probes

Proactive Diagnostics – Saves echo curves and offers troubleshooting tips when a problem occurs

For more information, contact Miller Energy, Inc. Call them at 800-631-5454 or visit their website at https://millerenergy.com.

Magnetrol Model A15 Single-Stage Displacer Level Control Switches

Displacer switch operation is based upon simple buoyancy, whereby a spring is loaded with weighted displacers, which are heavier than the liquid. Immersion of the displacers in the liquid results in buoyancy force change, changing the net force acting on the spring. The spring compresses as the buoyancy force increases.

A magnetic sleeve is connected to the spring and operates within a non-magnetic barrier tube. Spring movement causes the magnetic sleeve to move into the field of a pivoted magnet, actuating a switch mechanism located outside the barrier tube. Built-in limit stops prevent over stroking of the spring, under level surge conditions.

The minimum differential band is approximately 6 inches (152 mm) in water and varies somewhat with liquid specific gravity. The maximum differential is determined by the length of the displacer suspension cable. Series A15 units are calibrated to operate over a narrow level differential band and are ideally suited for liquid level alarm applications on either high or low level.

For more information about Magnetrol Displacer Level Switches, contact Miller Energy, Inc. Call them at 800-631-5454 or visit their web site at https://millerenergy.com.

How Do Magnetic Level Indicators Work?

Magnetic Level Indicators also known as MLIs, have revolutionized the global visual indication market by offering a safer, reliable, and high-visibility alternative to common gauge glass assemblies.  They provide high-visibility representation of the liquid level in a vessel. MLIs can be mounted to tanks in a number of different ways. The most popular configuration, however, is called a side-mount.

The Magnetic Level Indicator (MLI) working principle is widely used in many industrial level applications. The operating principle behind a magnetic level indicator is that the MLI shares the same process fluid as the vessel, and therefore shares the same level.

The three primary components to a Magnetic Level Indicator are:

• The float
• The chamber
• The visual indicator

The float (contained within the chamber) interacts with the externally mounted visual indicator. As liquid rises and falls in the vessel and MLI chamber, the float follows. The magnets in the float interact with magnets inside each indicator flag. As the float rises and falls in the chamber, the magnets slowly turn each flag 180 degrees. This allows the visible flag color to change to a high-contrasting, highly-visible representation of liquid level.







Utilizing a combination of proven buoyancy principles along with the benefits magnetism, MLIs can be customized to fit virtually any process connection arrangement on the vessel.

The chamber and magnetic float is available in a variety of materials and pressure ratings to accommodate the wide variety of complex process applications present in the world’s major industrial facilities.

Areas Where Magnetic Level Indicator Are Applied:

• Feed water heaters and boilers
• Refinery and chemical industries
• Energy and power plant technology
• Pulp and paper applications
• Oil and gas industries
• Gas plants
• Pipeline compressor applications
• Pharmaceutical applications
• Food and beverage applications

For more information about Magnetic Level Indicators (MLI's), contact Miller Energy by calling 800-631-5454 or visit their web site at https://millerenergy.com.

Selecting the Right Magnetic Level Indicator

Companies in the process industry need the ability to visually monitor liquid levels in vessels (boilers, storage tanks, separators, etc.). Traditionally, armored glass sight gauges have been used. However, many companies want an alternative to sight gauges to avoid problems such as breakage, leaks, or bursting at high pressures and temperatures. In addition, the visibility of the sight glass can be poor and often affected by moisture, corrosion, or oxidation.

Many companies are increasing the use of automation and desire a 4–20 mA, HART®, FOUNDATION® fieldbus, or other output for level—which is difficult to do with a sight glass. Magnetic level indicators (MLIs) do not have the shortcomings of glass sight gauges and are suitable for a wide variety of applications.

Orion Instruments, a Magnetrol company, has authored an excellent Magnetic Level Indicator selection guide.

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You can download the selection guide from this Miller Energy, Inc. web page.

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Miller Energy, Inc.
https://millerenergy.com
In NY/NJ 800-631-5454
In Eastern PA 888-631-5454

Level Instruments for Tank Overfill Protection

Tank overfill incidents in recent years have resulted in loss of life and billions of dollars in damages to petroleum facilities worldwide. One of the worst incidents - the overflow of a gasoline storage tank at Buncefield Oil Depot (U.K.) - has been traced to the failure of level control to maintain containment of the flammable liquid. More common are minor spills that cause significant environmental impact and result in millions of dollars in clean-up fees and environmental agency fines.

In the wake of this incident, the American Petroleum Institute’s (API) Recommended Practice (RP) 2350, the most widely accepted guideline for overfill protection of petroleum storage tanks, has been revised. The fourth edition was published in May 2012 and combined the prescriptive standards of RP 2350 with the functional safety standards of Safety Instrumented Systems (SIS) as described in IEC 61511.

Vital to these new requirements is the application of level instrumentation as one part of a comprehensive Overfill Prevention Process (OPP).

Magnetrol, a world-leader in the design, manufacturer and application of level and flow instrumentation, has written an application document titled "Level Instruments for Tank Overfill Protection". Get your copy here.

The Magnetrol ECHOTEL 962 Dual Ultrasonic Level Control

The Magnetrol ECHOTEL Model 962 is a dual point switch that can be used as a level controller, or to control pumps in an auto fill or auto empty mode. The tip sensitive lower gap performs well in aerated or foamy liquids, and can measure to within 1.4" of the vessel bottom. The rigidity of the unique flow-through upper gap allows separations of up to 125" (318 cm) between the upper and lower transducer gaps.

The Magnetrol ECHOTEL 962 offers the ultimate solution to reliable dual point liquid level measurement. This advanced switch uses pulsed signal technology for superior performance in difficult process conditions, and to provide excellent immunity from sources of electrical noise interference. Extensive self-testing of the electronics and transducer make this advanced switch suitable for use in Safety Integrity Level (SIL) 2 loops.

The ECHOTEL Model 962 is equipped with advanced diagnostics that continuously check the sensor and electronics. The diagnostics also alarm for electrical noise interference from external sources.

Ultrasonic contact switches use a pair of piezoelectric crystals that are encapsulated in epoxy at the tip of the transducer for level measurement. The crystals are made of a ceramic material that vibrates at a given frequency when subjected to an applied voltage. The transmit crystal converts the applied voltage from the electronics into an ultrasonic signal. When liquid is present in the gap, the receive crystal senses the ultrasonic signal from the transmit crystal and converts it back to an electrical signal.

Miller Energy, Inc.
https://millerenergy.com
800-631-5454

What Advantages Do Displacer Transmitters Have Over Differential Pressure Level Transmitters?

Displacer
Transmitter
(Magnetrol)

Many technologies have been available over the years have helped the process control industry with level measurement. From basic mechanical float-operated level switches, the process automation industry has been developing new technologies to make industry safer and more efficient.

An example of a "tried and true" technology that was commonly used in the process automation industry is the DP (differential pressure) level transmitter. First introduced in the 1950s, DP transmitters measures the hydrostatic (head) pressure of a liquid in a tank or vessel and interprets this as level, based on the density/specific gravity of the liquid and programmed in by the user. A newer, alternative technology to DP transmitters is the displacer level transmitter, a device also based on specific gravity. While they both are dependent on specific gravity, they are significantly different in areas of installation, accuracy, and maintenance requirement.

Application/Calibration

Applying a DP transmitter or displacer level transmitter requires experience and there are many factors to be considered. Here are a few:

DP transmitters use inferential measurement to determine level measurement from the hydrostatic pressure.  Despite requiring the specific gravity variable having to be programmed into the transmitter electronics, the level displacer transmitter is in contact with the process media and the level measurement is direct.

DP transmitters requires time consuming and expensive calibration/re-calibration if any of the set-up parameters change or if the same DP transmitter is used on different materials in the same tank.
Displacer transmitters only require two variables to be programmed (temperature and specific gravity), making it easier when running multiple products in the same tank.

Many displacer transmitters do not require liquid to be present for calibration. They are programmed (wet or dry) using software. A huge time and money saving over DP transmitters.

Mounting

The physical mounting of DP transmitters is limited, which can in some situations can become downright problematic. DP transmitters require (2) side-mounted entry locations on the vessel or tank, with one having to be near the bottom. As a general rule, the fewer the entry points of a tank or vessel, the better, because of leakage. Tank bottom entries all the more so.

Displacer transmitters are mounted to meet the requirements of the application and do not require a connection at the bottom of the tank.

Installation Cost

While DP transmitters have a lower unit cost, adding ancillary components such as tubing and heat tracing can quickly "level" the installation cost playing field. Furthermore, don't discount the time cost savings when setting up, calibrating and re-calibrating displacer transmitters.

Temperature Range

DP transmitters have a normal operating temperature of up to 250°F, with an upper limit of 650°F when special options are specified.

Displacer transmitter can be used up to 850°F, very helpful particularly with level measurement in a hot oil separator application.

There are many options and variants to accommodate industrial level applications. Share your level application challenges with instrumentation specialists, leveraging your own knowledge and experience with their product application expertise to develop the most effective solution.

Guided Wave Radar - An Option for Level Measurement in Hygienic Applications

A special version of the Magnetrol Eclipse 705
is configured for hygienic applications.
Image courtesy Magnetrol

Measurements of a variety of process conditions are utilized to monitor and control operations and output. One general goal of measurement, other than answering the question "how much", is to avoid or minimize any interference with the process itself. A second goal is to not be fooled by the process into returning a false measurement result.

Guided wave radar is based upon the principle of TDR (time domain reflectometry). Pulses of electromagnetic energy travel from the emitting antenna via a fixed waveguide or probe immersed in the target medium. When it contacts the media surface, the pulse energy is reflected back along the probe to a receiving antenna. The instrument actually measures the time elapsed between the pulse transmission and the detection of the reflected return. The time measurement is used to calculate the distance from the antenna to the media surface. The distance calculation, with knowledge of the vessel, can be converted into a value indicating media level or volume. Of course, this is a simplified account of the operating principal.

Guided wave radar (GWR), as opposed to an open style radar level measurement method, uses a probe immersed in the process media to guide high-frequency electromagnetic waves into the media being measured. While it does involve contact by the sensing instrument with the media, GWR eliminates interference from fixtures or structures that may exist within the tank or vessel. The immersion probe waveguide also attenuates the impact of media turbulence and other potential disturbances. The waveguide reduces the potential impact of elements that may adversely impact the measurement accuracy, resulting in greater accuracy and reliability of the measurements.

For hygienic applications, the transmitters are available with 304 stainless steel housings designed specifically for use in facilities with the special requirements for the wetted and non-wetted materials, process connections and surface finishes of hygienic industries. In addition to high accuracy, the GWR instrument output is not impacted by media buildup on the sensing probe.

Share your level measurement challenges with process instrumentation specialists. Leverage your own process knowledge and experience with their product application expertise to develop an effective solution.

Magnetrol Guide Wave Radar Level Transmitter For Hygienic Applications from Miller Energy, Inc.

Innovative Non-Contact Radar Liquid Level Transmitter

Pulsar R86 non-contact radar level transmitter.
Image courtesy Magnetrol

Level measurement of liquids and solids in containers, silos, tanks and other vessels is an essential part of many processing operations. Accurate and reliable measurement of solids or liquid level contributes to operational success, as well as enhancing safety, both of which contribute to the bottom line and successful operation.

Magnetrol, globally recognized innovator in flow and level measurement, incorporates years of experience into their latest version of non-contact radar level measuring instruments. The incremental improvements contribute to easier, more flexible installation and better performance.

The R86 is a 26 GHz level transmitter applicable across a wide range of requirements in many industries. Benefits of the 26 GHz radar signal, with its smaller wavelength, are a smaller antenna and improved 1mm resolution. The narrower beam from the antenna makes positioning the transmitter less restrictive, with easier accommodation for vessel fixtures or geometry. Advanced on board diagnostics supplement the improved performance and deliver the information needed to maintain proper operation and process visualization. A broad range of antennas and mountings are available for the R86, accommodating various tank sizes, fittings, and temperatures

More information on the Pulsar R86 is provided in the brochure included below. Share your level measurement challenges and requirements with a process measurement specialist. Employ the leverage of their product application expertise to your own process knowledge and experience to develop an effective solution.

Magnetrol Non-Contact Radar Level Transmitter Pulsar R86 from Miller Energy, Inc.

Top End Guided Wave Radar Level Transmitter

Magnetrol's model 706 embodies the best of guided
wave radar level measurement.
Image courtesy of Magnetrol

The Eclipse Model 706 is Magnetrol's loop powered high performance guided wave radar level transmitter. It incorporates many of the company's latest innovations into a single instrument capable of meeting the demanding requirements of an array of industrial applications.

Product improvements include increased signal to noise ratio, suitability for use with low dielectric media, and the ability to deliver accurate indication under foaming, flashing, or other challenging conditions. An extended probe offering enables use in measuring interface, liquified gas, even bulk solids.

The instrument is suitable for overfill applications, and does not use algorithms to infer measurements in a dead zone that may occur near the top of the probe in some other designs. The Eclipse 706 delivers true measurement right up to the process flange. Upgraded electronics allow the unit to be pre-configured prior to shipment, if requested. Additionally, the widest range of communications options is available.

For more information, share your level measurement challenges with a process measurement specialist. Leverage your own process knowledge and experience with their product application expertise to develop effective solutions.

Eclipse Model 706 High Performance Guided Wave Radar Level Transmitter from Miller Energy, Inc.

Level and Flow Instruments for Hygienic Applications

Magnetrol is a globally recognized leader in the manufacture of flow and level instrumentation for industrial scale applications. The products employ a range of differing technologies to provide measurement precision across an array of challenging applications. The informational piece included below highlights Magnetrol's products intended for use in industries, such as pharma or food processing, where special materials and product design are employed to meet the special requirements of hygienic processing.

Share your flow and level measurement challenges with process instrumentation experts, combining your own knowledge and experience with their expertise to develop effective solutions.

Life Science Applications and Products - Magnetrol from Miller Energy, Inc.

Pump Protection Using Thermal Dispersion Flow Switches

Thermal dispersion flow switches have advantages
when applied for pump protection
Image courtesy Magnetrol

Good practice for installing industrial pumps calls for inclusion of protective devices to assure that the pump is not exposed to conditions beyond its design intent. Monitoring liquid flow is a useful method for determining if a pump is operating within a safe range.

There are numerous methods of verifying flow in piping connected to a pump. Magnetrol, globally recognized manufacturer of flow and level measurement technologies, offers up their assessment of various pump protection measures and a recommendation for what they consider an advantageous choice for flow measurement in a pump protection application.

Magentrol's white paper is included below, and you can share your flow and level measurement challenges with application experts for help in developing effective solutions.

Pump Protection Using Thermal Dispersion Switches from Miller Energy, Inc.

Q&A for Ultrasonic Level Switches

Ultrasonic level switches with single
and multiple level measurement points
Courtesy Magnetrol International

Ultrasonic level switches appear, at first glance, to be a renamed version of a vibrating tuning fork level switch. They have a similar appearance and tank mounting scheme, but a closer look at the technology of the two instruments reveals that they rely on different operating principles to indicate when liquid level reaches their fixed switch point.

A previous article , with an accompanying video, provided some comparison between the two detection methods. Here is the operational difference summarized. A vibrating tuning fork device monitors the resonant frequency of the vibrating fork and responds when the frequency shifts due to immersion of the fork in liquid. An ultrasonic level switch transmits an ultrasonic pulse across a gap, measuring the intensity of the received signal and determining whether the signal passed through liquid (high level received signal) or air (low level received signal). While both technologies are effective, the ultrasonic level switch can be applied over a wider range of liquid density and does not require recalibration or adjustment for a change in media density.

Magnetrol International, globally recognized innovator in level measurement technology and instruments, recently answered a few application questions in their blog about their Echotel ultrasonic switches. The questions, along with answers penned by Magnetrol's product manager Tom Kemme, are shared here.

Question: Can ECHOTEL be used in applications that have entrained air?

Answer: Yes, ECHOTEL ultrasonic switches can be used in applications that have entrained air. All ECHOTEL gap switches feature a tip-sensitive transducer that provides superior performance over side gap transducers that are offered by other companies. Side gap transducers allow gas bubbles to adhere to the upper surface of the gap, which cause false dry gap alarms. Tip sensitive transducers allow these bubbles to pass through the gap. Applications with severe turbulence or entrained air should use the Model 961 switch, which offers a time delay adjustment. Up to 10 seconds of delay can be used to disregard entrained air and reliably detect the true liquid level.

Question: We are considering adding level alarm switches to our process to provide high-high level indication in several tanks. Instead of switches with relay outputs, we are considering the current shift output. What are the advantages of a current shift output?

Answer: Current shift electronics simply shift the current output from 8 mA when the level switch is in the normal operation, to 16 mA to indicate a level alarm. ECHOTEL Model 961 also has a user selectable fault signal of 3.6 or 22 mA. Current shift switches are 2-wire loop powered, which allows them to be offered with intrinsically safe approvals. This allows these switches to be put into hazardous area locations at a lower cost since rigid conduit is not necessary. Since current shift switches provide constant indication of either a normal (8 mA), alarm (16 mA), or a fault (3.6 or 22 mA) condition, they are sometimes referred to as a transmitter for the price of a switch.

Share your level measurement requirements and challenges with process measurement specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Accurate Level Measurement Contributes to Heat Rate Reduction

Industrial steam turbine

Steam production is a costly operation in any facility, but is of paramount importance in power generation plants. The bottom line of a combustion based power generation facility is sensitive to the cost of input fuel. Measures that can be taken to reduce fuel input for a unit of power output (called heat rate) can translate directly into profitability. An additional benefit of reducing heat rate is a commensurate reduction in emissions.

A major contributor to heat rate reduction is the recovery of heat from the process and transference of that heat into the boiler feedwater. A sizable feedwater preheater of the shell and tube type is used to recover the heat. Shell and tube heat exchanger efficiency can be maximized with accurate control of liquid level.

Magnetrol, globally recognized leader in level measurement technology, makes the case for using guided wave radar level measurement technology as the most advantageous means for this application. The video below describes the process and how the guided wave radar level transmitter can provide the best performance.

Magnetrol has an information kit devoted to heat rate reduction. Share your steam system and level measurement challenges with a product specialist, and ask how you can get the Heat Rate Reduction Kit. Combining your facility and process knowledge with the product application expertise of a specialist will result in effective solutions.

Thermal Mass Flow Meter Q&A From Magnetrol

Thermatel® thermal mass flow meter
Courtesy Magnetrol®

Sometimes you discover that others do something better than you. When that happens, watch and listen.

Tom Kemme, from Magnetrol®, expertly fielded some questions about thermal mass flow meters in a recent blog post. Mr. Kemme's responses were so useful and clear that I decided, with all the credit flowing his way, to share them here for those of you that may not closely follow the Magnetrol® Blog.

Question: What is the difference between the flow units Nm3/h, Sm3/h, and actual m3/h?

Answer: Actual m3/h is a flow rate at operating temperature and pressure. Normal or standard m3/h (Nm3/h = Sm3/h) is a flow rate at standard temperature and pressure (STP). I tend to reference the natural gas industry, where it is not possible to compare flow rates at every operating condition, so it is preferable to reference all flow rates back to a set of base conditions, such as 60°F and 1 atm. STP is not universal so it may be unique based on the region or industry.

Most flow meters output a flow rate at operating conditions and need to correct this measurement. This may be accomplished with a multivariable transmitter or external to the device. A few examples that do not need to correct the measurement are thermal mass flow meters, such as the ones produced by MAGNETROL, and Coriolis flow meters.

Question: Do you have any certified failure rate data on your units to perform an SIL verification?

Answer: A Failure Modes, Effects, and Diagnostics Analysis (FMEDA) is completed during development to determine failure rates and Safe Failure Fraction (SFF). The SFF is utilized to determine Safety Integrity Level (SIL), which is often the published value.

Question: What should my meter be reading with no air flow in the pipe?

Answer: At zero flow and a dry pipe, a thermal mass flow meter should measure zero. Different thermal meters may have varying stability at no flow due to differences in operation.

There are two different types of operation: constant temperature (CT) and constant power (CP). CT devices start with a low power and this power increases with the flow rate to maintain the constant temperature difference (ΔT) between the RTDs. CP devices start with a high ΔT between RTDs at low flow and the ΔT decreases as the flow rate increases. CP may lack stability at zero flow due to possible convection currents associated with the high ΔT. CT will hold zero better, particularly devices that add less heat. For example, the maximum surface temperature of a TA2 probe is 4 C above process temperature. This is extremely low heat, eliminating convection currents due to the sensor. Convection currents could also occur through the pipe due to temperature variations.

It is also possible for a thermal meter to measure above zero during a no flow condition when there is pressure buildup in the line (typically a valve closed downstream). There may be low flow cutoff settings that can be changed to ignore nuisance measurements.

You can easily tap into Magnetrol® expertise to solve your flow measurement challenges. Reach out to a product specialist and combine your process knowledge with their flow measurement expertise to develop effective solutions.

Electronic Displacer Liquid Level Transmitter - How it Works, When to Use It

Electronic displacer liquid
level transmitter using spring
technology
Courtesy Magnetrol

An electronic displacer liquid level transmitter is intended for industrial applications requiring the continuous measurement of liquid level in a tank, vessel, or other containing space.

Magnetrol, a globally recognized leader in the design and production of level measurement instrumentation, describes the operating principle of their Digital E3 Modulevel® displacer level transmitter:

Electronic displacer level transmitter technology operates by detecting changes in buoyancy force caused by liquid level change. These forces act upon the spring supported displacer causing vertical motion of the core within a linear variable differential transformer.

The movement of the core within the LVDT generates an electrical signal which is further processed and serves as the output of the transmitter. The unit is designed to be externally mounted on a tank. Isolation valves are recommended.

The spring technology employed as a counterforce to the buoyancy of the displacer results in a stable signal that is not impacted greatly by vibration, agitation, or turbulence of the measured liquid.

The video below provides more detail, covering the features and advantages of this level measurement technology and the Magnetrol instrument. Share your level measurement challenges and requirements with a product application specialist. The combination of your process knowledge and their product application expertise will produce effective solutions.