Radar Level Gauges Prove Versatile, Reliable

A choice of protocols, little or no maintenance, and accuracy in tough applications yield satisfaction with Saab Rosemount Tank Control's TankRadar Rex Series

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Radar level gauges are used to measure level in bulk liquid storage tanks typically found in refineries, pipeline terminals, liquefied natural gas terminals, and aviation fuel depots. Applications include inventory calculations, custody transfer, blending control, leak detection, and overfill protection.

 

Users like the no-moving-parts reliability and communication flexibility of TankRadar Rex.

A recent market study from Venture Development (www.vdc-corp.com) finds that, among the many technologies used for process level measurement and inventory tank gauging, the highest market growth rates through 2007 are expected to be for non-contact microwave/radar.

Now in use for several years, TankRadar Rex radar gauges from Saab Rosemount Tank Control (www.tankintelligence.com) handle varied and difficult applications with little or no maintenance, users say. The gauge family consists of five types optimized for various applications. Each gauge calculates the level of the liquid's surface using tank distances stored in the gauge. The tank level is then communicated on a digital fieldbus to Saab Rosemount field communication units or to other host systems.

Each radar gauge is connected to a transmitter head and antenna. The same head is used on all Rex tank gauges. The head is interchangeable between different gauges, regardless of antenna type. The enclosure of the transmitter head is rated IP-66 and 67 to provide protection from air and water.

Refineria Isla SA in Curacao, Netherlands Antilles, has used Saab Rosemount gauges in three applications over a two-year period. The gauges are used in a bitumen coned roof tank with an internal temperature of about 175* C and in a huge fuel oil floating-roof tank with a ballast tank and roosters inside the tank. "The obstacles inside the tanks make the application difficult, but the Saab Rosemount radar gauge can handle it," according to Raymond Mansana, instrument section head of shipment and movement.

Refineria Isla uses Saab Rosemount gauges that emulate the GPE protocol. "The protocol emulation feature allowed us to use the existing wiring and supply power," adds Mansana. He says installation is easy because of the light weight (18 lbs.) of the gauge: "One person can install the gauge without any problems."

Oiltanking GmbH in Hamburg, Germany, has 49 Saab Rosemount gauges installed on API 650 tanks used to store gasoline and gasoil. Twenty-five of the gauges have been in operation for three years; the other 24 for one year. "The best feature of the gauges is there are no moving parts in the system that can wear," says Reimund Schwarz, a project manager with Oiltanking. "The gauges have been very reliable once we solved some start-up problems with the communication between the radar head and the Tankmaster software."

Schwarz would like to see Saab Rosemount reduce the size of the gauge in future product iterations. "The unit is a little too big compared with the radar gauges sold by competing vendors," he says. "It would be nice if Saab could reduce the size and the price."

Another Oiltanking installation in Houston has five Saab Rosemount gauges, with five more due for installation shortly. "We are very satisfied with the operation of the gauges, but we would like Saab to offer a handheld instrument for gauge setup and service," says Michael Johnson, Oiltanking maintenance technician.

Kinder/Morgan Energy, Bloomington, Calif., installed its first Saab gauge in 1994 and now has 10 units in place. The gauges are installed on all new tanks and are retrofitted to old tanks as they are maintained and overhauled. The tanks store refined petroleum products.

"Compared to mechanical-type systems, the Saab gauges don't have problems of gauge tapes, chives, and transmitters," says Timmy Lee Pruett, project specialist with Kinder/Morgan. "Current regulations make the cost of maintaining mechanical systems prohibitive. The cost of replacing a tape can surpass the cost of a complete Saab unit."

As with other users, communication flexibility was a major reason for selecting Saab Rosemount. "The interface box for communications using existing protocols is critical and has worked very well," says Pruett. "Ease of installation and a choice of 120 VAC or 48 VDC supply power makes the unit adaptable to any system."

The Bahamas Oil Refining Co. uses the gauges to measure level in crude oil, fuel oil, diesel, and gasoline in fixed and floating roof storage tanks. The first gauge was installed in 2001, and four more have been added in the past two years.

Greg Cooper, instrument/electrical supervisor, says radar is better than other level sensing technologies because there are no moving parts, and the Saab Rosemount gauge has proven to be better than other radar gauges because it is extremely reliable.

"The best features of the Saab gauge are its accuracy (within 1/32 in.) and its durability," Cooper adds. "The radar gauges have worked very well for us to date, and we are planning to install an additional 43 this year."

For more information call 800/722-2865 or see www.saabrosemount.com.

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