Thursday, January 26, 2017

Advanced Pressure Transmitters for Process Measurement

pressure transmitter for industrial process measurement
Direct mount pressure transmitter
Courtesy Azbil
The measurement of pressure is a common task throughout many industrial spheres. Depending on the application, a wide range of process or machinery operation status can be derived from a pressure reading. Accuracy, ruggedness, and flexibility in application are hallmarks of a useful pressure transmitter.

Azbil North America advanced pressure transmitters offer a combination of features that can make them an advantageous selection for almost any application.

  • Stability of +/-0.1% for 10 years
  • Little to no downtime for calibration
  • Sensor technology that provides day-one accuracy for the life of the transmitter
  • Customizable display
  • Alarm outputs
  • Fast response
  • International standard certifications
The advanced pressure transmitter is available in variety of mounting configurations to suit most applications. More information is contained in the document included below. Share your process measurement challenges with application experts, combining your own process knowledge and experience with their product application expertise to develop effective solutions.



Wednesday, January 18, 2017

Application of Limit Switches on Automated Industrial Valves

industrial valve automation actuator and limit switch
Employed in a wide range of industrial applications,
limit switches are known for ease of installation,
simple design, ruggedness, and reliability.
Courtesy Flowserve Automax
Limit switches are devices which respond to the occurrence of a process condition by changing their contact state. In the industrial control field, their applications and product variations are almost countless. Essentially, the purpose of a limit switch is to serve as a trigger, indicating that some design condition has been achieved. The device provides only an indication of the transition from one condition to another, with no additional information. For example, a limit switch triggered by the opening of a window can only deliver an indication that the window is open, not the degree to which it is open. Most often, the device will have an actuator that is positively activated only by the design condition and mechanically linked to a set of electrical contacts. It is uncommon, but not unknown, for limit switches to be electronic. Some are magnetically actuated, though most are electromechanical. This article will focus on limit switch designs and variants used in the control and actuation of industrial process valves.

Valves, devices used for controlling flow, are motion based. The movable portions of valve trim create some degree of obstruction to media flow, providing regulation of the passage of the media through the valve. It is the movement of critical valve trim elements that limit switches are used to indicate or control. The movable valve trim elements commonly connect to a shaft or other linkage extending to the exterior of the valve body. Mounting electric, hydraulic, or pneumatic actuators to the shaft or linkage provides the operator a means to drive the mechanical connection, changing the orientation or position of the valve trim and regulating the media flow. Because of its positive connection to the valve trim, the position of the shaft or linkage is analogous to the trim position and can be used to indicate what is commonly referred to as “valve position”. Limit switches are easily applied to the valve shaft or linkage in a manner that can provide information or direct functional response to certain changes in valve position.

In industrial valve terms, a limit switch is a device containing one or more magnetic or electrical switches, operated by the rotational or linear movement of the valve.

What are basic informational elements that can be relayed to the control system by limit switches? Operators of an industrial process, for reasons of efficiency, safety, or coordination with other process steps, may need answers to the following basic questions about a process control valve:

  • Is the valve open? 
  • Is the valve closed? 
  • Is the valve opening position greater than “X”? 
  • Has the valve actuator properly positioned the valve at or beyond a certain position? 
  • Has the valve actuator driven the valve mechanism beyond its normal travel limits? 
  • Is the actuator functioning or failing? 
Partial or complete answers to these and other questions, in the form of electrical signals relayed by the limit switch, can serve as confirmation that a control system command has been executed. Such a confirmation signal can be used to trigger the start of the next action in a sequence of process steps or any of countless other useful monitoring and control operations.

Applying limit switches to industrial valve applications should include consideration of:

  • Information Points – Determine what indications are necessary or useful for the effective control and monitoring of valve operation. What, as an actual or virtual operator, do you want to know about the real time operational status of a valve that is remotely located. Schedule the information points in operational terms, not electrical switch terms. 
  • Contacts – Plan and layout a schedule of logical switches that will provide the information the operator needs. You may not need a separate switch for each information point. In some cases, it may be possible to derive needed information by using logical combinations of switches utilized for other discrete functions. 
  • Environment – Accommodate the local conditions and hazards where the switch is installed with a properly rated enclosure. 
  • Signal – The switch rating for current and voltage must meet or exceed those of the signal being transmitted. 
  • Duty Cycle – The cycling frequency must be considered when specifying the type of switch employed. Every switch design has a limited cycle life. Make sure your selection matches the intended operating frequency for the process. 
  • Auxiliary Outputs – These are additional contact sets that share the actuation of the primary switch. They are used to transmit additional signals with specifications differing from the primary signal. 
  • Other Actuator Accessories – Limit switches are often integrated into an accessory unit with other actuator accessories, most of which are related to valve position. A visual local indication of valve position is a common example. 
Switches and indicators of valve position can usually be provided as part of a complete valve actuation package, provided by the valve manufacturer or a third party. It is recommended that spare contacts be put in place for future use, as incorporating additional contacts as part of the original actuation package incurs comparatively little additional cost.

Employing a properly configured valve automation package, with limit switches delivering valve status or position information to your control system, can yield operational and safety benefits for the life of the unit. Good advice is to consult with a valve automation specialist for effective recommendations on configuring your valve automation accessories to maximize the level of information and control.

Friday, January 13, 2017

Electronic Line Break Detection - Pipeline Monitoring

electronic line break detector for oil and gas pipelines
Electronic line break detector unit
Courtesy Rotork
There are some process control challenges for which you may need to establish or produce a solution of your own design. These should be applications where a pre-engineered option or product is not available. A manufactured product for your application likely is comprised, not only of appropriate physical attributes suitable for the application, but also the experience gained from numerous successful iterations solving the same problem, challenge, or issue you currently face. There can be expertise, knowledge, and experience provided as part of a hardware item, and bringing that knowledge and experience of others into the solving of a process control challenge is sound practice.

Pipelines, when considered from differing organizational vantage points:

  • A source of revenue
  • A means of transportation
  • A pipe with fluid in it
  • An ongoing operation requiring monitoring and control
  • An extensive physical presence with an associated risk element
Pipelines are all those and more. Regardless of your vantage point, line breaks are decidedly negative events worthy of early detection and rapid response. Part of that solution is available in the electronic line break detection device from Rotork, globally recognized leader in the design and manufacture of valve actuators employed throughout the industrial sphere. The ELB model incorporates a set of features and capabilities that can be used to detect and respond to gas pipeline breaks. It is a self contained unit employing technology to detect line breaks and execute a predetermined response.

Read more about the ELB from Rotork in the document included below. It provides a detailed outline of the operational features of the unit. Share your fluid system control challenges with an experienced application team, combining your process knowledge with their product application expertise to develop effective solutions.



Tuesday, January 3, 2017

Application of Flame Scanners in Combustion Operations

single burner flame scanner sighting or alignment
Aim flame scanner through the largest cross sectional area of the flame
Courtesy Fireye
Flame detectors or scanners are regularly deployed in combustion applications as a means of confirming the presence of flame in a combustion chamber. The verification that fuel flowing into the utilization equipment is being properly burned and not accumulating unburned in the combustion chamber is the first line of safety in combustion.

Flame scanners use the characteristics of combustion and the electromagnetic emissions from burning fuel to detect flame and distinguish among flames from multiple burners. The instruments rely heavily upon operating principles utilizing visible, infrared, and ultraviolet light measurement and detection.

In single burner applications, simpler sensor and controller combinations can work suitably, but multiple flame applications are candidates for more complex detection devices and controls which can discriminate among multiple flames. Differences in individual flame characteristics, indicated through combustion products, can be utilized to distinguish between flames from different burners. Some photoelectric detectors can distinguish a signature flicker in flames of any type, invisible to the human eye.

Knowledge and understanding of the flame itself, its emissive attributes, and other characteristics are the key to proper flame detection. This may include the temperature of gases within the flame and its specific gas products. Other than temperature, electromagnetic radiation and ionized gas molecules in the flame are commonly used by flame scanners or detectors.

A variety of flame scanners are available for industrial and commercial use, each optimized for particular application sets. Essentially you have a scanner, which acts as a sensor. The signal from the scanner requires amplification and further processing to provide a reliable control signal. Hardware is available as discreet components, allowing a combination of scanner, amplifier, and control units to be combined into a system tailored for specific application requirements. Integrated systems are also available, with all appropriate detection and amplification circuitry built into a single compact unit.

Share your combustion process challenges with application specialists and combine your facility and process knowledge with their product application expertise to develop effective solutions.