Thursday, September 29, 2016

Magnetic Liquid Level Gauges

magnetic level indicator with auxiliary tube for guided wave radar
Magnetic level indicator with supplemental
guided wave radar instrument
Gemini Model - Magnetrol
Magnetic liquid level gauges are an excellent alternative to sight glass level gauges for many process measurement applications. Their reliable performance and adaptability has made them the primary choice in a wide variety of industrial settings.

Essentially, a magnetic level gauge or magnetic level indicator, is a sight glass with enhancements that provide better readability and a form factor that enables the inclusion of additional level monitoring functions on the same device. Where a sight glass requires operator proximity to read liquid level, the magnetic level gauge's indicating scale, or flags, can be clearly viewed from a considerable distance. A sight glass gauge can also be hindered by difficulties in visually determining liquid level because of deterioration of the glass surface or properties of the liquid. Magnetic level gauges remove the need to observe the liquid directly by incorporating a float device within a tube connected to the liquid containing vessel. As the float moves in response to liquid level changes, its magnet causes the indicator flags on the scale to rotate and display either a black face to indicate no liquid present, or a colored face.

Magnetic level indicators are available with numerous options, including armored casings to protect the tube and float arrangement and limit switches to signal the attainment of specific level conditions. Combining a MLI with another level measurement technology, such as guided wave radar or magnetorestrictive, can provide an analog process signal representing liquid level and serve as a redundant measuring device for critical applications.

The document included below provides illustrated detail about the devices and their proper application. Share your process measurement requirements and challenges with instrumentation experts. The combination of your process knowledge and their product application expertise will produce effective solutions.


Tuesday, September 20, 2016

Comparison of RTD and Thermocouple for Process Measurement

industrial temperature sensor rtd or thermocouple
Industrial Temperature Sensor
Courtesy Wika
Proper temperature sensor selection is key to getting useful and accurate data for maintaining control of a process. There are two main types of temperature sensors employed for industrial applications, thermocouple and resistance temperature detector (RTD). Each has its own set of features that might make it an advantageous choice for a particular application.

Thermocouples consist of a junction formed with dissimilar metal conductors. The contact point of the conductors generates a small voltage that is related to the temperature of the junction. There are a number of metals used for the conductors, with different combinations used to produce an array of temperature ranges and accuracy. A defining characteristic of thermocouples is the need to use extension wire of the same type as the junction wires, in order to assure proper function and accuracy.
Here are some generalized thermocouple characteristics.
  • Various conductor combinations can provide a wide range of operable temperatures (-200°C to +2300°C).
  • Sensor accuracy can deteriorate over time.
  • Sensors are comparatively less expensive than RTD.
  • Stability of sensor output is not as good as RTD.
  • Sensor response is fast due to low mass.
  • Assemblies are generally rugged and not prone to damage from vibration and moderate mechanical shock.
  • Sensor tip is the measuring point.
  • Reference junction is required for correct measurement.
  • No external power is required.
  • Matching extension wire is needed.
  • Sensor design allows for small diameter assemblies.
RTD sensors are comprised of very fine wire from a range of specialty types, coiled within a protective probe. Temperature measurement is accomplished by measuring the resistance in the coil. The resistance will correspond to a known temperature. Some generalized RTD attributes:
  • Sensor provides good measurement accuracy, superior to thermocouple.
  • Operating temperature range (-200° to +850°C) is less than that of thermocouple.
  • Sensor exhibits long term stability.
  • Response to process change can be slow.
  • Excitation current source is required for operation.
  • Copper extension wire can be used to connect sensor to instruments.
  • Sensors can exhibit a degree of self-heating error.
  • Resistance coil makes assemblies less rugged than thermocouples.
  • Cost is comparatively higher
Each industrial process control application will present its own set of challenges regarding vibration, temperature range, required response time, accuracy, and more. Share your process temperature measurement requirements and challenges with a process control instrumentation specialist, combining your process knowledge with their product application expertise to develop the most effective solution.

Thursday, September 15, 2016

Ultrasonic Contact Level Switches Provide Reliable Overfill Protection

ultrasonic contact type level switches
Echotel® Ultrasonic Level Switches
Magnetrol
Requirements for safety regulation compliance continue to grow. Business operators want increased levels of risk aversion and contingency management. In industrial settings where fluids are processed or stored, meeting these goals calls for new layers of protection and redundancy for existing layers.

Tank overfill is a serious concern of any fluid processor. Providing multiple methods of measuring tank or vessel fluid level provides substantially greater assurance against overfill. One scheme involves using a continuous level measurement instrument, such as guided wave radar, to provide the real time tank level signal and an ultrasonic level switch as a tank overfill indicator.

The operating principal of an ultrasonic level switch is quite simple. A transducer sends an ultrasonic pulse across a gap. When liquid media is present in the gap, the sound wave is transmitted with little attenuation across the gap and detected. When liquid media does not fill the gap, the sound wave is strongly attenuated and fails to transmit across the gap.

Tuning fork level switches are commonly applied as the overfill detection device, but Magnetrol, a recognized global innovator in level measurement, feels they have a better solution with their Echotel® ultrasonic level switches. The video below provides an illustration of how the ultrasonic level switches can be applied, as well as a comparison between ultrasonic and tuning fork methods.

Share your level measurement requirements and challenges with a product application specialist. The combination of your process expertise and their product application skill will produce an effective solution.


Thursday, September 8, 2016

Use Manifold Valves With Pressure Transmitters

manifold valves for pressure transmitters and gauges
Manifold Valves for Pressure Gauges and Transmitters
Pentair - Anderson Greenwood
Pressure transmitters are generally fixed in place, but require regular access for calibration and operational testing. Unlike instruments used to measure some other process conditions, a pressure transmitter is directly connected to the process, making it's removal problematical. Manifold valves provide a compact and effective means of access and isolation needed to perform regular maintenance and calibration operations while maintaining the pressure transmitter in place.

A single pressure transmitter or gauge can be served by a simple 2-valve manifold. One valve provides isolation of the instrument from the process. The second valve opens to atmosphere on the instrument side of the isolation valve. This allows the pressure transmitter or gauge to be isolated from the process and connected to a calibration source. Here is a schematic example.
Certainly, any qualified technician can cobble together this arrangement from a pile of valves and fittings. The advantages of using a manifold valve are several.
  • High pressure rating
  • Reduced leakage potential
  • Compact size
  • Comparatively rapid installation
There are numerous manifold valve configurations to accommodate any valve and gauge requirement. Manifold valves can also be used in other applications for making effective and convenient connection arrangements between instruments and processes. Share your connectivity challenges and requirements with process instrumentation specialists, combining your process knowledge with their product application expertise to develop the best solutions.



Tuesday, August 30, 2016

Thermal Dispersion Flow Meter For Compressed Air and Nitrogen Measurement

thermal dispersion mass flow meter
Thermal Dispersion Flow Meter
Magnetrol
Monitoring compressed air usage in a factory or other operation where it is consumed is essential for proper system maintenance and attainment of energy efficiency goals. The ability to track down leaks and monitor compressed air usage enables stakeholders to work toward maximizing the return on an asset with substantial initial and operating costs.

Easy installation and simplicity of operation are advantages for any instrument applied in this manner, making compressed air flow measurement a good application for a thermal dispersion flow meter. With no moving parts and a simple operating principal, a thermal dispersion flow meter can be quickly installed and put into operation. A digital display of the flow measurement provides local information, and a networking connection or other signal output can provide for remote or centralized monitoring and data collection.

A cut sheet is included below that provides detail on technological, operational, and installation aspects of this simple and effective instrument. Share your flow measurement challenges with application experts, combining your own process knowledge with their product application expertise to develop cost effective solutions.


Monday, August 22, 2016

Setting Up the United Electric Controls Series One Safety Transmitter

Here is a two part tutorial showing how to setup your United Electric Series One Safety Transmitter. If you need any additional help or product information, reach out to a product specialist.

Part One Video

Part Two Video

Tuesday, August 16, 2016

Safety Transmitters For Temperature and Pressure

safety transmitter for industrial process control pressure temperature
Series One Safety Transmitter
United Electric Controls
Industrial history is replete with examples of catastrophic accidents. New safety technologies exist today that can prevent or mitigate mishap and disaster in fluid processing and other operations. Modern philosophy of plant safety brings a focus on a proactive approach. Process operators have a new sense of urgency to bring increased levels of safety to their operations.

The United Electric Controls (UE) Series One is a SIL-certified (Safety Integrity Level) transmitter designed solely for safety, alarm, and shutdown. With reliability, speed, and reduced nuisance trips an integral part of its design, the Series One is suitable for application in new installations, or easily integrated into existing operations.

A typical safety loop consists of sensors (such as a pressure or temperature transmitter), controllers, and final control elements. Most SIL-rated pressure transmitters require 300ms to communicate with the controller, then up to 500ms for the controller to send a signal to the final control element (such as a valve). This combined response time may insufficient for some applications. Incorporating the One Series Safety Transmitter, directly connected to the final control element, the total signal time is reduced to 100ms - a large and significant time savings when safe operating conditions have been breached. When used with blowers, pumps and compressors, the One Series makes up a complete safety system with a self-contained sensor, controller, and final control element (the switch) capable of SIL2 without additional safety instrumented function (SIF) components.

The below document provides detailed information about the Series One. Share your process safety challenges with the instrumentation specialists and combine your process knowledge with their product application expertise to produce effective solutions.