• Whessoe Varec Asia-Pacific Office

Servo Gauge For Measuring Storage Tank Fluid Levels

Whessoe Varec has launched a compact servo gauge capable of measuring storage tank fluid levels with an accuracy of ?0.8 mm, a new standard for this form of process variable transmitter. Combined with the ability to accommodate fluid densities from 400-1,200 kg/m3, and options for high pressure working, the instrument facilitates advanced inventory management solutions for the vast majority of media found in chemical, petrochemical, oil and gas processing industries. Its versatility simplifies instrumentation and control strategies for large installations such as tank farms, allowing most or all measurement needs to be met by just one type of gauge. Designated Model 770, the gauge works on the displacer principle, and can be fitted with float discs to suit different media-made from materials such as SS 316, aluminium alloy 3571 or PTFE. It will operate in two modes: as a level only gauge, or a combined level, density and water bottom gauge-transmitting data from external sensors. Standard versions work at pressures up to 6 bar. Optionally, the instrument is available in materials to allow it to monitor high pressure tanks, up to 40 bar. Built-in intelligence enhances flexibility of application, providing programmable wave integration to ensure that measurement accuracy can be maintained even when dealing with difficult media or problematic tank shapes. There are also five programmable alarms, allowing warnings or action signals in addition to conventional high and low level points. The 770's communications interface is designed for adaptability, and may be fitted with modules to integrate with all kinds of control system, including 4-20 mA loops, Modbus or other digital serial links. Uniquely, a second communications interface may also be fitted, for fault tolerance in high risk or highly automated environments. In addition to boosting fundamental measurement performance, the 770 is believed to break new ground in lowering lifecycle costs, due to an emphasis on reliability engineering during development. Minimisation of moving parts, plus the isolation of electronics from vapour through a magnetically coupled compartment, results in an MTBF of 12 years. This allows Whessoe Varec to offer the gauge with a 2-year warranty-double the industry norm. Careful attention has also been paid to maintainability and repair, through features such as remote configuration and diagnostics via the communications interface, the elimination of virtually every part requiring routine servicing, and a built-in LCD for local messages. Parts have been designed for easy removal and replacement, facilitating an extremely low MTTR (mean time to repair) figure of just 25 minutes. This modularity extends to the communications interface(s), making upgrade to new network protocols-something which almost every tank farm will do over the next 10-15 years-simple to achieve. The Whessoe Varec 770 is certified to Cenelec EEx d IIB T6, with FM and CSA approvals pending, and meets NMI standards for custody transfer applications. The 770 has been brought into the Whessoe Varec range by virtue of the company's recent acquisition of CGAI of Italy, where early sales have proven the performance and reliability of the instrument. The gauge's capability was enhanced to ensure compatibility with standard Whessoe Varec communications protocols.