Evolution in nucleonic measurement

Apr 17, 2012 | Flow & Level

Nucleonic gauges are used where other technologies prove unreliable, or safety considerations demand a second technology for redundancy. However, they retain an ‘air of mystique’ for site technicians. VEGA?has designed its

PROTRAC range of nucleonic measurement detectors with the objective of simplifying the application of the technology.

VEGA have over 60 years experience of working with nucleonic products, since the Ohmart Corporation (now VEGA Americas Inc.) released their first product. VEGA now introduce the full  PROTRAC range of nucleonic measurement detectors for level, interface, density and weighing, which are designed with the clear objective of simplifying the application of the technology.  As leaders in radar level measurement, they have used many of the advances in their plics® range and developed the new product in compliance with SIL for both continuous measurement and point level detection to IEC/EN 61508.

Modern detectors contain a scintillator, photomultiplier and evaluation electronics. Scintillators are some of the most sensitive instruments for measuring radiation.  PROTRAC electronics have been developed to work with extremely low levels of radiation, to minimise the activity of the source required.  When gamma radiation interacts with the atoms within the crystal or plastic scintillator, photons are produced. These flashes of light reach a photomultiplier which amplifies them and converts them into electrical impulses. The impulse rate per second (counts) is then converted by the processing electronics into a level, switching or density signal.

Caesium sources are typically used in industrial measurement. The decay of the atoms occurs randomly, which provides a ‘noisy reading’ if un-filtered.  So there is always a requirement to use a time constant to allow for fluctuations in energy from the source.  This means it is necessary to balance  the speed of response required, with source activity and the accuracy of measurement. So high accuracy means a slower response, and vice versa. VEGA have developed a special adaptive filter that continually evaluates and adjusts the time constant for optimal performance.  The filter time changes based on the process reading, thus providing maximum accuracy during stable process conditions and a quick response to fast process changes.

Like all other plics® based transmitters from VEGA, all electronics are field replaceable as one plug-in module. The transmitter head is available in light weight epoxy painted aluminium, or 316 Stainless Steel for corrosion protection, both with ATEX certification.

Ease of mounting

The FIBERTRAC series for level measurement provides ease of mounting through a unique patented Fibre optic scintillator to provide a flexible, light weight detector of up to 7m long that easily contours around vessels.

The MINITRAC density gauge is compact and able to clamp on to any pipe to measure density completely externally from the process. It has a quick set up menu for calibration, the adaptive filter works particularly well for this technology. This technology is ideal for lined pipes, high temperatures, aggressive and abrasive products. A remote electronics version is also available when heavy plant vibration is present.

Calibration of the PROTRAC range is easily achieved using the PLICSCOM display, PACTWARE software, or via a customers DCS system.

The PLICSCOM back-lit LCD display module allows setup of the application and calibration of the instrument. It can be mounted in the transmitter head, or remotely in a local display housing. It is also intrinsically safe for hazardous areas.

PROTRAC can also be setup via PACTware FDT/DTM multi manufacturer software, which can be used on all VEGA technologies. The instrument setup can also be achieved remotely from within the customer’s DCS system using FDT/EDDL drivers. In addition to 4-20 mA HART output, Profibus and Foundation Fieldbus communication is also available. Whichever option is selected, it makes set up of PROTRAC flexible, simple to understand and easy to calibrate.

Meet the family

The PROTRAC family consists of five models; FIBRETRAC and SOLIITRAC for level, POINTRAC level switch, MINITRAC for density and WEIGHTRAC for non-contact mass flow on conveyors etc.

If you would like further information or a product demonstration contact info.uk@vega.com  or call 01444 870055 and ask for sales.

VEGA Controls

T:?01444 870055                 

 E: info.uk@vega.com