Showing posts with label Level Control. Show all posts
Showing posts with label Level Control. Show all posts

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.

Interface in the Field: Achieving Reliable Interface Measurement to Optimize Process and Increase Uptime

Interface or multiphase level measurements exist throughout the Oil & Gas streams as well as Petrochemical. While level measurement technologies have come a long way in effectively measuring liquids and solids, multiphase level measurement continues to be the biggest challenge and opportunity that exists today to which there is no perfect technology.

However, experience has shown that process optimization and increased uptime can still be achieved in many separator applications through reliable, best-in-class, level technology.

The objective of this paper is to review interface challenges, the current technologies being utilized for interface, field experience in various applications to achieve process optimization and increased uptime, and the future of reliable interface measurement.


Courtesy of Magnetrol and Miller Energy, Inc.

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.

Water and Wastewater Treatment Applications for the Magnetrol R82 Pulse Burst Radar Transmitters

The Magnetrol R82 Pulse Burst Radar transmitter performs across a wide range of applications. The R82 is designed to provide radar reliable process measurement in challenging, vapor saturated environments, at the cost of what you pay for an ultrasonic device. For water treatment, the Magnetrol R82 Pulse Burst Radar transmitter provides continuous level measurement at the lift station and coagulant feed tanks, in settling tanks during clarification, in polymer, filter, and lime slurry tanks during filtration, and for open atmosphere water reservoirs where the control technology must withstand punishing weather conditions.  In wastewater facilities, the R82 radar can control level at the lift station pump, open channel flow and screening system, monitor feed tanks containing chemical coagulants oxidants and phosphorous precipitation, measure splitter box in clarifier levels, control corrosion inhibitors, manage pH adjustment, mixed liquor and secondary clarifier levels, as well as activated sludge and digester level control.

Miller Energy, Inc.

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.

Q&A for Ultrasonic Level Switches

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.

Opportunity For Improving Power Plant Heat Rate

electric power plant
Opportunities for improving efficiency at power plants
The large scale of most power plants provides a environment in which financial justification, or payback, of attempts to improve energy consumption can be justified. Even small improvements in efficiency can yield very substantial returns. The challenge to engineering and management is to select the projects which have the best overall probability of success and can be integrated into the process with the least amount of disturbance.

One area of the steam cycle that may be a candidate for improvement is the feedwater heater. This device is essentially a shell and tube heat exchanger used to recover waste heat from the process and use it to preheat boiler feedwater. Maintaining the correct liquid level in the feedwater heater is a key element of extracting maximum performance. Magnetrol, a globally recognized leader in the development of level measurement equipment, has produced a video showing how their technology can be used in an advantageous manner to others in regulating feedwater heater liquid level and achieving maximum efficiency.

Optimizing Level Control in Combined Cycle Gas Turbine Plants

Magnetrol® International and Orion Instruments®, both recognized global innovators in level measurement technology, provide optimizing solutions for liquid level control in combined cycle gas turbine plants and other similar applications.

An overall cost analysis can reveal savings in the range of 25% to 35% through the application of the most advantageous level measurement technology. Miller Energy, Inc. has developed a short presentation and discussion regarding recent developments now available in the Magnetrol® Eclipse Line of guided wave radar level instruments.

More detail is provided on the single page document provided below. Reach out to Miller Energy and learn how your operation may benefit from the application of guided wave radar level measurement technology.

New Level Transmitter From Orion Instruments

Orion magnetostrictive level transmitter
Direct insertion and external mount versions of
Orion JM4 Magnetostrictive Level Transmitter
Courtesy Orion Instruments
Orion Instruments, a world class manufacturer of magnetic level indicators, level switches, and level transmitters, has released a new product for use in the industrial process measurement and control field. Their Jupiter Model JM4 magnetostrictive transmitter incorporates the company's many years of research, development, and field experience to provide a safer, simpler, and smarter transmitter for liquid level measurement and control.

The new model from Orion boasts level measurements with accuracy as high is +/-0.05" (1.27mm). The transmitter head can be rotated up to 310 degrees with an option for remote mounting. Variants are available for direct insertion or external mounting, with approvals for a number of area classifications. There are other valuable features to this series of level measurement instruments that reflect Orion's expertise in the field.

Browse the new product brochure included below. It provides illustrations of the product and its operating principle, along with dimensioned drawings and a listing of all the product options and variants. You can always obtain whatever information you need about Orion level measurement instruments from a product specialist. Share your liquid level measurement challenges and requirements with them for recommendations on the best solutions.

Digital Sensor Technology: An Uptick in Measurement Performance

Electron microscopy image of Yokogawa DPharp silicon resonant sensor
Silicon Resonant Sensor
Courtesy Yokogawa
Industrial process control, as a field of endeavor, is a continuous quest for better, safer, and higher output. The road of progress is paved with new technologies that deliver higher accuracy and reliability in measurement. A recently commercialized advance is the silicon resonant sensor used to measure pressure in industrial process settings. One manufacturer, Yokogawa, applies this technology throughout their DPharp line of differential pressure transmitters, with numerous industrial applications.

Some of the positive attributes of this latest generation of digital pressure sensor include:

  • Simultaneous measurement of differential and static pressure.
  • Superior digital precision
  • No A/D conversion needed
  • High performance 
  • Temperature effects limited to 10 ppm/deg Celsius, yielding highly stable performance
  • High signal to noise ratio
  • Output level increase of more than four times over previous generation piezoresistance silicon sensor

The features all add up to a substantial improvement over previous technology, delivering an incremental step up in measurement performance and confidence. You can quickly boost your understanding of how the sensor technology works by viewing the short video below. To explore how the Yokogawa DPharp sensor equipped transmitters can provide better performance to your process, contact a product specialist and share your process measurement challenges.

High Speed, High Performance Control for Weighing Operations

Industrial batch process tanks
Industrial Batch Process Tanks
Industrial process control implies the presence of industrial process measurement. Throughout our operations, we seek to measure "how much" of something is present. In the case of many materials, weight is the preferred measurement.

Weight is a measurement of force. We can use it as a statement of "how much" because gravity is considered constant across the planet surface. The force I measure for a batch of material in the US will, for commercial purposes, be the same force measured for that material after I ship it to somewhere else. Measurement of weight can be used for establishing proper mixing ratios of components to be combined in a particular manner. The level of material in a tank or other container can be ascertained through a measurement of weight.
In our processes, higher throughput and accuracy are always in demand.
The Vishay Precision Group's BLH/Nobel Weighing Systems operating unit manufactures a high speed, high performance control for industrial weight/force measurement applications. Their G4 line of controllers provides the user a wide range of configurable options, from multiple input channels to analog and digital outputs. The clean user interface provides access to all functions and channels and the unit is available as a freestanding desktop, DIN rail mount, or panel mount unit. There is also a model configured for harsh environments.

The video below provides a good overview of the unit and its potential applications. Contact a product specialist to receive more details, or to discuss how the G4 might be helpful to your process operation.

Guided Wave Radar for Hygienic Applications: Advantages Over Other Technologies

Guider Wave Radar
Guided Wave Radar
for Hygienic
Operating Principle

Guided wave radar is based upon the principle of TDR (time domain reflectometry). Pulses of electromagnetic energy travel via the waveguide. The pulse is reflected when it contacts a liquid surface and the distance is then calculated.

Guided wave radar transmitters are available with a 304 stainless steel housings designed specifically for use in hygienic applications. This instrument meets the needs and requirements for the wetted and non-wetted materials, process connections and surface finishes of hygienic industries.
  • Low dielectric measurement capability (╬Ár >_ 1.4)
  • Volumetric output
  • Quick connect/disconnect probe coupling
  • Operates in visible vapors and ignores most foams
  • IS, XP, and Non-Incendive approvals
  • Ignores coating buildup
Advantage Over Other Technologies
  • Advantage over Differential / Hydrostatic Pressure Transmitter:  Replaced by Eclipse due to setpoint shifts, blockage, leakage, installation cost & long term calibration / maintenance
  • Advantage over Magnetostrictive: Replaced by Eclipse due to setpoint shifts, turn-down and clean ability & long term calibration / maintenance.
  • Advantage over RF Capacitance: Replaced by Eclipse due to dielectric shifts, coating issues & long term calibration / maintenance.
  • Advantage over Load Cells: Eclipse is more cost effective and long term cost of ownership is lower due to long term calibration / maintenance.
  • Advantage over Ultrasonic: Replaced by Eclipse due to vapors, condensation, temperature restrictions, foaming & turbulence.
  • Advantage over Through Air Radar: Replaced by Eclipse due to performance issues on low dielectric media, short range measurement because of dead band issues in small vessels, measurement issues when using false echo rejection from internal obstructions such as agitators and spray balls, signal attenuation from turbulence, foam, condensation and spray from spray balls used during cleaning or product filling. Through air radar can have issues from variable false echoes generated when spray hits the antenna when vessel is filled from spray balls.
For more information see this Guided Wave Radar bulletin: