Monday, September 26, 2016

Industrial Thermowell Styles: Straight, Tapered, and Stepped Shanks

industrial thermowells
Industrial thermowell styles courtesy of REOTEMP
A thermowell is a machined tube intended to protect or seal off a sensing element from the process media. They are available in many materials and process connections.  There are three common body styles (referred to as shanks) used on thermowells: the straight shank, the taper shank, and the step shank. This post will explain the difference in styles.

Straight Shank
The straight shank has the same diameter throughout its entire immersion length. Because of its greater diameter and thicker tip, it usually has the slowest response time compared to other shank styles. However, the extra metal allows it to have a high corrosion and high abrasion resistance. Common installations for a straight well are tanks or pipes to have low pressure, low-velocity and/or a high abrasion process. Although the straight shank has the best mechanical strength properties, it should not be used in high-velocity flow systems. Its larger surface area can be overly disruptive to flow, or it may fail due to vortex shedding.

Tapered Shank
The second design is the tapered shank, which has an outside diameter that gradually decreases from the point just under the process connection, down to the tip. This taper allows for a very high mechanical strength, with a faster response time than a straight well. This design has very good vibration resistance and is commonly used and high-velocity flow applications. Common installations for a taper well are applications with a very high flow rate, high vibration, high-pressure and are high temperature.

Stepped Shank
The final type of shank is the stepped shank. Usually this type of well is a straight shank from the process connection down to about two and a half inches from the tip, with the final two and a half inches a smaller diameter straight shank. The reduction in diameter allows for a faster response - usually the fastest response out at three different shank designs. There is however a reduction in strength because of the diameter change, and less mechanically rugged as a straight or tapered shank style. Common installations for a step well are where rapid response is needed, but without high-velocity flow or where there is a possibility of being physically damaged from the process media.

Thursday, September 22, 2016

Water & Wastewater Open-channel Flow Measurement: Effluent Flow Measurement for Dual V-notch Weir

Nivelco for wastewater treatment
V-Notch Weir Flow Measurement
Nivelco for wastewater treatmentWastewater treatment plant effluent flow measurement is a common application that can be accurately measured with ultrasonic level transmitters. However, a US municipality presented an an application where two v-notch weirs in parallel to handle the flow requirements was proving more than a typical ultrasonic level transmitter could handle. A better solution had to be found.

Nivelco for wastewater treatmentThe existing flow meter that had failed after just two years of operation. The major problem was the flow meter on the effluent never matched what they were receiving on the input and thus passing bad data. The maintenance crew found that the preferred brand of ultrasonic level sensor, combined with a different brand flow meter, was prone to failure. They needed a reliable way to measure flow going across both v-notch weirs and add flow pacing to the other process controls.

After careful review of the operating conditions and required specifications, a NIVELCO EasyTREK
ultrasonic level transmitter with the MultiCONT universal display and controller was selected for this unique flow meter and level measurement application.
Nivelco for wastewater treatmentThe IP68 rated EasyTREK SPA-38N-4 integrated ultrasonic level transmitters are installed on a console above the basin. The units use HART digital communication to connect in multidrop loop to the MultiCONT multi-channel process controller. The MultiCONT is able to provide remote programming while displaying the process variables in real-time.

The instrument’s calibration was adjusted to read the flow across both v-notch weirs and send the data back to the central SCADA system, PLUS using the additional output of the MultiCONT to flow pace UV disinfection and the systems effluent wastewater sampler.

Nivelco for wastewater treatmentThe complete NIVELCO measuring system proved to be an excellent solution, providing highly reliable operation and high accuracy.

For more information on this application or for applying level and flow transmitters for any wastewater or water treatment need, contact:

Arjay Automation
1178 E. Cliff Road
Burnsville, MN 55337-1577
Phone (800) 761-1749
Fax (612) 861-4292

Wednesday, September 21, 2016

Measurement and Monitoring of Process Conditions is an Essential Part of Producing the Desired Output

Prozess Technologie
Prozess Technologie Reveal 
Measurement and monitoring of process conditions is an essential part of producing the desired output. Some operations require, or can benefit from, faster or more accurate measurement of process variables. This can be especially true for chemical processes that rely on accurate mixing of components.

Process analyzers are available in a wide variety of technologies, configurations, performance ranges, and price points. Selecting the best analyzer for a particular process, take into consideration these points.
  • Technology - Assess whether the technology is cabable of producing the results needed 
  • Accuracy - Measurement at levels appropriate for the process and operating goals 
  • Specificity - Ability to reliably measure the subject components 
  • First cost 
  • Continuing costs of maintenance, expendables, calibration 
  • Ease of use and integration into overall process measurement and control scheme 
  • Reliability 
One manufacturer, Prozess Technologie, approaches process analysis with their Reveal optical spectroscopy analyzer. It is capable of operating continuously without ongoing operator interaction. Internal calibration software provides stability and reliability. The software suite for the instrument is compliant with numerous standards and a host of communication standards are supported to allow for easy integration into a process measurement and control system.

Pick up more detail about the Reveal unit below. Share your analytical process challenges with a product application specialist. Combining your process knowledge with their product expertise will produce effective solutions.

Monday, September 12, 2016

The Basics of Industrial Thermcouples

thermocouples
Variety of sheathed thermocouples
 (courtesy of REOTEMP)
Industrial thermocouples are used for a very broad range of temperature sensing applications. They are inexpensive, accurate, and can be fabricated in many forms to meet the requirements of the process. They operate on the "Seebeck Effect" which is the phenomena of dissimilar metal conductors producing a measurable voltage difference between two substances.

Thermocouples are used widely in industrial processes in industries such as power generation, primary metals, pulp and paper, petro-chemical, and OEM equipment. They can be fabricated in protective wells, and can be housed in general purpose, water-tight, or explosion-proof housings.

Thermocouple types - such a type J, type K, type R, and type S - refer to the alloy combinations used for the conductors and are based on standardized color designations. 

The following video provides a basic visual understanding of thermocouple wire, how a T/C junction is determined, and also discusses thermocouple connectors, polarity and some aspects of construction (such as grounded vs. ungrounded vs. open tip).



For more information on any industrial temperature sensor, contact:

1178 E. Cliff Road
Burnsville, MN 55337-1577
Phone (800) 761-1749
Fax (612) 861-4292