Measurement Innovative Instrumentation Package Offers Inexpensive Level Measurements

Editor: Dr. Jörg Kempf

Within a short space of time, Endress+Hauser has upgraded its complete range of level gages to the state of the art and adapted them to market requirements. The manufacturer has new products for nearly all 13 of the different measuring procedures. The three lifetime-based measuring procedures with the revised Micropilot (freely radiating radar), Levelflex (guided radar) and Prosonic (ultrasonic) form a real “power trio”.

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( Archiv: Vogel Business Media )

With the aim of creating greater transparency and reducing complexity, the level gage specialists at Endress + Hauser (E+H) set about a thorough overhaul of their product portfolio. Wherever possible and meaningful, the aim was to standardize the product portfolio. At the same time, the aim was to expand the breadth of applications and the areas of use, as well as facilitating standardized, simple and intuitive operation of the equipment. The company has started the new year with a clear promise: when it comes to measuring levels of fluids and solids, users should now be able to solve even the most difficult of applications with a better solution and a more precise match.

And what are the products with which the company is looking to keep this promise? What form do these innovations take? Below, we look in greater detail at the particularly successful lifetime-based measuring procedures (this year already sees the 750,000th lifetime device being manufactured!). With the “Time-of-Flight Powertrio” of Micropilot, Levelflex and Prosonic, E+H is offering all three procedures: freely radiating radar, guided radar and ultrasound.


Power Number 1: Freely radiating radar

With fluids under extreme process conditions (pressure, temperature) and with gas-emitting (and aggressive) media, contact-free radar level measuring is a safe solution. The further development of this measuring principle also facilitates its use with bulk materials practically regardless of dust and fill noise. The Micropilot works with high-frequency radar impulses which are radiated by an antenna and reflected back by the surface of the bulk material. The lifetime of the reflected radar impulse is directly proportional to the distance it has traveled. By determining this distance, it is possible to calculate the fill level in the equipment. The frequency ranges used by the radar devices are around 6 and 26 GHz.

“Radar technology is improving in performance year on year. In autumn 2006, we succeeded in improving dynamism for fluid applications with newly-developed E+H high-frequency modules by a factor of 60 for our freely radiating Micropilot type radar devices,” reports Carsten Schulz, Product Manager for Level Gage Engineering at E+H. “This advance in development, in combination with the new PulsMaster eXact evaluation software, increases the reliability of the measured values significantly.” For fluids, the range of applications has broadened considerably; according to Schulz, the procedure now offers greater reliability even at low relative dielectric constants, with turbulent surfaces and modest foaming. For bulk materials, the further development of the high-frequency modules has seen an increase in dynamism by a factor of 1,000 being achieved, with the result that fill levels up to 70 meters can be reliably measured. With the new generation of devices, a consistent “look and feel” has been realized, along with common operating tools for taking into service, and both diagnosis and documentation have been optimized. The simple, comprehensibleparameterization functions do not require any specialist knowledge on the part of the user. Since January of this year, E+H has also been offering what to its knowledge is the only available 26 GHz pulsed radar device with an accuracy of ±1 mm on the mandatory calibration device market.

Power Number 2: Guided radar

Measuring fill levels using guided radar impulses is suitable both for bulk materials (rope probes) and for fluids (rod probes and coaxial probes). The reason for this is that the clear passage of the reflected waves means that the nature of the surface of the medium plays only a subordinate role. Different feed cones or discharge funneling, as can occur with bulk materials, do not influence the measurement. Reliable measurement is guaranteed even with turbulent fluid surfaces or foaming, according to E+H. The Levelflex M works with high-frequency radar impulses which are fed along a probe. Where the impulses meet the surface of the medium, the characteristic impedance alters and a part of the transmit pulse is reflected. The period measured and evaluated by the device between the transmission and reception of the reflected impulse is a direct measure of the distance between the process source and the surface of the medium.

“The latest version of our Levelflex M guided level radar is particularly outstanding for the high reliability of its measurement values,” stresses Norbert Thomann, also a Product Manager for Level Gage Engineering at E+H. “The reason for this is that in demanding applications two redundant measuring procedures are running in parallel in a single device – a genuine unique selling point for our product.” The device measures 99 percent of the reflection on the surface, and also something known as the probe end displacement. In other words, there is a normal measurement process, with a second process in the background. The product range is particularly well-suited for installation in a bypass. Measuring points of this kind, which can be supplied as a complete solution, play a key role especially in the chemicals and petrochemicals industries and in power stations. The new fluid devices measure at up to 400 °C and 400 bar.

Power Number 3: Ultrasonic

Ultrasonic is generally considered the proven solution for measuring levels in fluids and bulk materials, with typical areas of application being abrasive and aggressive media, even under rough ambient conditions. The principle of measurement is characterized by simple design and assembly, fast and safe taking into service, a long operational lifetime and reduced maintenance expenditure. The Prosonic family of devices works with ultrasonic impulses which are reflected by the surface of the medium due to the change in density between the air and the medium. The period measured and evaluated by the device between the transmission and reception of the reflected impulse is a direct measure of the distance between the sensor membrane and the surface of the medium.

With the Prosonic S, the ultrasound fill gages have now been consistently further developed. Hans-Peter Maier, Fill Gage Product Manager at E+H, details the latest innovations: “Comprising an evaluation unit and sensor, the device offers key advantages as separate instrumentation, particularly in rough, inaccessible and hazardous environments; these advantages offer winning arguments when considering fitting the device and taking it into service.”

Thus the user has the choice between a top hat rail finish for space-saving fitting in the control cabinet and a robust, weather-resistant field housing for open-air wall mounting. The user-friendly process for taking the device into operation is supported by automatic recognition of the connected sensor, and by the step-by-step user guide taking him through the parameterization process in various national languages.

Success lies in diversity

But, of course, this does not mark the end of development in lifetime procedures at E+H. True to the slogan that “Only metrological diversity, on the basis of the widest variety of physical measurement principles, guarantees solutions on an optimal price/performance basis“, this complete solutions provider offers a comprehensive product range: from microwave barriers (Soliwave) to radiometry (Gammapilot), vibronics (Liquiphant, Soliphant), plumb-line systems (Silopilot), capacitive procedures (Liquicap), conductive procedures (Liquipoint), hydrostatic procedures (Waterpilot, Deltapilot, Deltabar, Cerabar) and differential pressure procedures (Deltabar) through to float switches and paddle switches. As E+H puts it, this means that they offer solutions and expertise in all sectors of process engineering „from A to Z“ in fluids, bulk materials and liquefied gases. The aim of “People for Process Automation” is to offer every user the best solution for his application – both in terms of the measurement engineering and in terms of an economical solution.

In normal instances, there are two or three alternative measuring procedures which suggest themselves for every application. E+H add that they naturally support the user in making this choice, offering simple aids to planning and decision-making. For example, customized solutions are provided by the Applicator, a smart piece of software which is freely available on the internet (see InfoClick for download). Once the customer-specific process parameters have been entered, it shows the various options from which the user can choose his favored solution, taking into account framework conditions such as price, need for maintenance or individual preferences. A further positive spin-off is that using the right device in the right place increases plant availability and avoids expensive unplanned plant downtimes.

The E+H promise further extends to a service for taking the fill gages into operation, if requested. And in addition to its repairs service, a helpdesk is available for round-the-clock telephone support. Furthermore, the company also supplies complete solutions, such as bypass measurements. These are supplied with assembled and parameterized measurement systems. The time needed to fit the systems and take them into service at the plant is consequently reduced. To that end, the experts provide comprehensive documentation, such as CAD drawings, system alignment logs, lists of accessory parts and safety certificates such as AD2000, DGRL and 3.1 certificates.

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