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Level Measurement Technologies Plumb-Bobs and Yo-Yo’s: These provide acceptable results until the ash coatings and abrasiveness create mechanical problems. The cables that are typically wound up on a spool device when retracted would bind, and once coated, would not fit on the spool causing system failure. This requires the devices to be disassembled and rebuilt. The maintenance costs incurred would eventually become unacceptable. RF/Capacitance: Due to the stratified layers of ash with different dielectric constant, this technology does not produce acceptable results. Level measurements could be off as much as 30% or more. The low dielectric constant of Fly Ash and the temperature extremes make reliable setting of a traditional capacitance probe difficult. The sensitivity needed for low dielectric product detection often leaves the probes in a state where false triggers can be caused with changes of temperature. Ultrasonic: Due to dust, angle of repose, long measurement ranges and occasional higher temperatures produced unpredictable and unreliable results. Admittance: The admittance technology has proven to be the best available technology for level measurement in Fly Ash. The admittance probes have a stable oscillator core which exhibits almost no drift with process temperature changes. The high stability allows higher sensitivity to be used when setting switch points, and so greatly improves the ability to reliably detect products having lower dielectric constants. High temperature ceramic insulation is used in the construction of a heavy duty probe for Fly Ash applications. The rugged 36mm stainless steel sensing element will withstand heavy impact loads without bending or damage. Lighter duty versions and Teflon insulated versions are also available for less demanding process conditions. For these reasons, the admittance switch is deemed best technology for Fly Ash applications.

Conclusion It is important that a properly maintained level monitoring system be implemented to prevent material from backing up in the hopper and damaging the equipment, reducing precip efficiency or both. Offering a simple combination of point level measurement and communication technology, Hawk’s Gladiator Admittance Smart Switch has proven accurate and reliable in Fly Ash applications. The Gladiator Smart Admittance Level Switch is designed to accurately detect the level of Fly Ash and communicate to the de-ashing operation. Once the Hopper reaches “full” capacity, the Gladiator communicates to the de-ashing operation to start the emptying process. The Gladiator is suitable for a broad range of dielectric constants and rated for high temperatures, up to 450ºC. The Admittance Smart Switch accurately measures the Fly Ash, is immune to build-up, features interface detection, automates the empty process, prolongs lifespan of equipment, minimizes hopper overflow, and is one of the most precise and reliable technologies on the market for this application.