Back in the late 1990s, my business partners and I had been engaged in performing downhole imaging services for oilfield well completions. I personally had previously experimented with wireless data telemetry for drill site automation; however, the commercially available analog data radios of the era were extremely susceptible to interference and proved far less than reliable.
One of our partners was introduced to a principal in a major aboveground storage tank (AST)/floating roof firm who subsequently enlightened us about some new digital wireless technology developed for military applications. His primary goal was to provide overfill protection for tanks that were isolated by waterways and other obstructions. We eagerly accepted his challenge and used the newly available digital frequency-hopping spread spectrum technology to meet this goal.
Since this wireless technology worked remarkably well in tank farms, we then set about researching the feasibility of using this wireless scheme to develop a tank inventory management system. Naturally, the major challenge was to identify and adapt a technology that could be battery powered for a reasonable time period. We quickly discovered the only practical approach (from a power-consumption standpoint) was magnetostrictive. We decided to attempt to implement this technology, which is employed in virtually all underground storage tanks (UST), and discovered to our delight it offered many other attractive benefits for ASTs. Magnetostrictive has been used in almost all USTs since the 1960s because it offers the following standard features:
- Average temperature measurement
- Water bottom measurement
- Extremely high-level resolution, repeat-ability and accuracy (~± 0.03 millimeters) • Mature technology with excellent reliability and low maintenance
These features are required for USTs because volumetric leak detection must be continuously performed. Unfortunately, the commercially available mag probes at the time were only available in lengths up to ~7 meters, so many enhancements and a lot of innovation were needed to accommodate ASTs up to 21 meters in height.
After nearly a year of development, the AST inventory management solution (using magnetostrictive technology) was born, which provides a completely battery-powered, intrinsically safe wireless solution for virtually any tank up to 21 meters tall. Because the magnetostrictive technology provides average temperature and bottom water measurements, the final output is net volume at standard temperature. Because these mag probes allow the assignment of alarm setpoints at any tank level, overfill protection is fully redundant when the completely separate wireless overfill protection system is used in conjunction with the inventory management system.
The objections to wireless and batteries are rapidly diminishing as both technologies have blossomed rather magnificently in the past decade, and the certainty of even more astounding breakthroughs in the near future make this endeavor all the more exciting. The tank transmitters are configured to routinely test the batteries and provide advance notification for battery replacement.
Perhaps my most intriguing observation is the primary goal for deploying these systems has changed since we began their development. Today, the principal incentive for deployment of this technology is to avoid the trenching required for electrical conduits in tank farms needed for conventional tank monitoring systems. Apparently, no one wants to discover what might be lurking just below the surface.
For more information, visit www.omntec.com, or contact Larry Taylor at larryt@omntec.com or (281) 222-6961.