Plants Take Measurement to a Higher Level

Although the market for level measurement sensors is expected to decline by nearly 15% this year, growth will resume late next year or in early 2011 — driven in particular by the requirements of the chemical, petrochemical and pharmaceutical sectors. So says a market study released in mid-August by VDC Research Group, Natick, Mass. Increased demands for efficiency gains and regulatory compliance are fueling that long-term growth, it notes.

VDC ranks Endress+Hauser (E+H), Emerson Process Management, Vega Grieshaber, Yokogawa Electric and Siemens Milltronics Process Instruments as the top five suppliers of process level measurement devices worldwide. “It is critical to remember that this market is highly fragmented, with dozens of other segment leaders operating in very specific technical or installation environment niches,” cautions Chris Rezendez, VDC’s president. Indeed, Chemical Processing’s latest Readers’ Choice survey (www.ChemicalProcessing.com/articles/2009/133.html) offers a somewhat different ranking — Emerson, E+H, Ohmart Vega and Magnetrol. Our survey doesn’t look at market share but instead at which vendors readers consider technology leaders in 44 categories.

Improved technology promises to redefine the role of level instruments. “With a wealth of information now available, what was once a simple level switch or transmitter for monitoring and control purposes may now be a powerful source of valuable long-term process data. By understanding the wide range of level measurement technologies available, engineers in the chemical sector can take full advantage of their different benefits and applications,” notes Tim Chettle, marketing manager, level and pressure products, for Emerson’s Mobrey Measurement Division, Slough, U.K.

Magnetostrictive Approach

Figure 1. This technology, originally aimed at linear displacement, has been adapted to level applications.
Source: MTS Systems.

While technological advances certainly are improving level measurement capabilities, they also are posing challenges, as Dr. Egon Held, senior automation manager at BASF’s Instrumentation Technology Department in Ludwigshafen, Germany, explains: “Level measurement technology is used by BASF in a wide field of applications and we have a lot of experience in applying not only well-established but also the latest non-contact technologies on the market such as radar or laser. In the last few years, the performance of these systems has increased significantly, so that now many more measuring tasks can be solved. However, their application and configuration is rather complex and we have specialists to find the optimum parameters for level detection in the different chemical processes.”

One of the company’s strategies for dealing with this challenge is to use only approved device types from selected suppliers. “A standardized test procedure has to be completed in our centers of technical expertise including site tests. We have an internal standard list for instrumentation to assure that only proven-in-use level measuring equipment with high functionality and reliablity is installed in our plants.”

Solving Long-Term Problems
Today’s advanced measurement solutions can address process challenges that have dogged some plants for ages.

Guided Wave Radar Transmitter

Figure 2. This two-wire unit can handle challenging measurements on liquids, slurries and solids.
Source: Emerson Process Management.

For example, in September E+H, Kildare, Ireland, completed a major overspill protection project for Apollo Adhesives in Tamworth, U.K. that solved a persistent problem. Apollo, whose core products are a range of solvent-based adhesives, was having trouble measuring very-low-dielectric-value mixed and chlorinated solvents with stored in underground vessels. The manual measurement method used was time-consuming and not precise enough. The company required an accurate and reliable automated system that would provide real-time data and give low-level alerts to avoid running out of stock as well as high-level alerts to avoid overspill. It also had to be electrically suitable for a zoned explosive area.

The low-level alarms were particularly important as Apollo wanted to ensure that raw materials always were readily available to meet customer demand and to facilitate ordering in bulk from suppliers to reduce delivery costs. The high-level alarms, meanwhile, would help protect the environment and employees from danger.

E+H supplied eight Levelflex M FMP40 coaxial guided-wave-radar (GWR) devices that accurately measure low dielectric materials and also comply with the necessary electrical requirements. Additionally, E+H installed eight RIA261 loop-powered field displays in the hazardous area for use by tanker drivers during filling operations. A separate panel next to the hazardous area incorporates all hardware to generate the high- and low-level alarms as well as a siren and beacon — and provides signals to an additional panel situated inside the main office building.

This system provides Apollo with direct access to real-time data about the level of raw materials and thus plenty of time to replenish stocks when levels get low.

As a result, the company now saves on transportation costs by avoiding repeat deliveries by suppliers, and frees staff from having to take the manual measurements. More importantly, Apollo reduced the risk of running low on stock or completely running out of stock, which would lead to manufacturing downtime and incur great costs.