The Consumer Guide to Industrial pH and ORP Instrumentation David B. Mills A completely independent guide to industrial pH and ORP instrumentation ranked by performance and supplier (limited to eight major world-wide manufacturers of pH and ORP instruments).

Rooftop Maker Solves Burning Problem New clamp-on ultrasonic flow technology brings temperature control to hot process

This guide contains technical information about evaluating and applying pH and ORP instruments with pointers for installation. Tables include the types of pH and ORP instruments and selected features that are available from each supplier, along with their country of origin or source.

Tallant Industries, Inc., a manufacturer of corrugated asphalt roofing panels, was searching for a solution to a burning problem that was causing delays in their process. Tallant’s plant in Fredericksburg, Va., produces what they consider a revolutionary roofing product. The corrugated asphalt roofing materials consist of paper impregnated with bitumen for water resistance. A critical component of the company’s production is bitumen storage. Bitumen presents a challenge in that

tures, which allow clamp-on flow measurement at temperatures of up to 752°F (400°C).

Cowden said the devices allowed the company to verify the problem wasn’t in the HTO circuit, but was build-up of coke from the bitumen on the heat transfer coils.

By means of cooling fins, the transducers move away from the measurement point. Engineering of these plates allows areas reflecting heat to be 100 times larger compared to the

“The basic problem in measuring the flow of gases or liquids at high temperatures is survival of the transducers that generate and detect the ultrasonic signals,” O’Brien said.

This guide is indispensable for designers, engineers, owners and end users of pH and ORP instruments. See where your instrument ranks and use this guide to help you choose your next pH and ORP instruments.

Format: Softbound book ISBN: 1-932095-09-8 Length: 100 pages; Weight: 1 lb. Member: $225.00; List: $250.00 www.isa.org/pHandORP

Consumer Guide to Non-Contact Level Gauges David W. Spitzer and Walt Boyes This is an updated and independent guide to the world’s ultrasonic, laser, and radar non-contact level gauges, ranked by performance and by supplier. The guide contains technical information about evaluation and application of level gauges with pointers for installation, such as material, vapor, vessel, sensor, and electrical considerations. Tables include the types of level gauges and selected features that are available from each supplier, along with their country of origin or source. This guide is indispensable for designers, engineers, owners and end users of level gauges. See where your level gauge ranks and use this guide to help you choose your next ultrasonic, laser or radar level gauge.

high temperatures and its viscous, sticky nature require maintaining tight temperature control throughout the process.

During the process, manufacturers move bitumen from a heated vessel to a smelter where they heat it to 375°F (190°C) just prior to using it for impregnation and coating. They heat the bitumen vessels and smelter via 2-in pipes flowing heat transfer oil at 540°F (282°C). Maintaining the proper flow rate of the transfer oil is critical to getting the heat transfer efficiency they need to heat and maintain bitumen at the right process temperatures.

They typically measure heat transfer oil (HTO) on a 2-in pipe at a temperature higher than 540°F (282°C). The company said a diagnostic tool to measure this HTO circuit has not been available up to this point. The flowmeter they used in the past failed repeatedly because of the high temperature. “This application is extremely problematic for intrusive metering technologies because of the high temperatures, abrasive nature of the liquid, and high flow velocities,” said Allan Cowden, Tallant’s lead plant engineer. Because the company emphasizes safety, Cowden said they now must avoid potential leakage due to new metering technologies, such as flange connections. As a result, they needed a non-intrusive measurement method for such a highly flammable aggressive medium.

To overcome these limits, the company
looked to high-temperature pipe mounting fix-

areas conducting heat. This results in a significant temperature gradient between the pipe wall and the transducer surface area. The drop in temperature is large enough to permit standard temperature rated transducers to see use in high temperature applications exceeding 750°F without reliability or performance degradation.

“Flow measurement at high temperatures is problematic by itself,” said John O’Brien business development and operations manager with Flexim Instruments LLC in Bohemia, N.Y. High media temperatures (>500°F) have in the past posed problems for non-intrusive ultrasonic manufacturers. Thermal stress in magnetic flowmeters causes ceramic liner cracks. So they’re only suitable for measuring up to 356°F (180°C). Vortex shedding meters cover a higher temperature range than magnetic meters, but they are too expensive for large pipe diameters and wouldn’t provide the lower flow rate performance this application needs. Even non-intrusive ultrasonic meters, “which are in principle ideal for corrosive and aggressive media,” have seen limited use at high temperatures, he said. One reason is the sound coupling gels these meters require have a 482°F (250°C) maximum temperature tolerance. High temperatures accelerate the aging of the ultrasonic transducers’ piezo elements and limit their useful operating life.

For full In Tech^® story, go to www.isa.org/intech/20060402.

Format: Softbound Book – 2005 ISBN: 1-932095-07-1 Length: 100 pages; Weight: 1 lb. Member: $225.00; List; $250.00 www.isa.org/noncontact

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