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opgd.jpg (15934 bytes) Zellweger Analytics Limited has introduced the new Sieger Searchline Excel infra-red Open Path Gas Detector System (OPGD) for hydrocarbon gases. Consisting of a separate transmitter and receiver unit, the system is the latest development from the market leader in gas detection equipment for offshore installations and on-shore hydrocarbon processing plants. It is designed to initiate plant shutdown procedures in the event of gas release and reduce explosion risk. It meets the needs of operators who demand that such instrumentation should provide virtually 100% availability to prevent downtime and loss of valuable productivity.

The Searchline Excel Open Path Gas Detector will monitor a hydrocarbon gas release or cloud as it passes through an invisible infra red detection beam, which operates over distances of 5 to 200 metres.

It has been designed as a result of a customer partnership approach between Zellweger Analytics and major oil and petrochemical companies who have been actively involved in its three year development from the design stage through to prototypes, field trials and the finished product.

OPGD is a highly effective means of monitoring flammable gas with significant advantages over point gas detectors which rely on gas reaching a detector at one given point or location. It is therefore possible that the prevailing wind / air direction or any change in direction may take a gas release away from a point gas detector. In addition, the further the point gas detector is away from the source of the leak, the greater the degree of dilution until the concentration is below a detectable level.

A high intensity light source pulsed at a special coded frequency generates a much stronger infra red beam enabling it to penetrate further through fog and rain.

Carefully selected sample and reference wavelengths makes Searchline Excel free from the problematic absorption of infra red light by the O-H bond of water vapour.

The receiver unit utilises unique solid state detectors offering the widest dynamic range and improved linear response to incident light compared to that employed on previous OPGD systems. This, in conjunction with temperature compensation, provides exceptional baseline stability even under conditions of direct sunlight and rapidly changing temperature, fog or rain. Searchline Excel is guaranteed to be 100% solar immune and has extended operational availability in thick fog.

Ultra fast digital signal processing using the latest microprocessors enables rapid signal averaging and filtering. Searchline Excel automatically rejects interference from vibrations or bright reflections. Unique low energy internal heating prevents the formation of condensation or a build up of snow and ice over the optical surfaces thereby increasing system availability.

Searchline Excel uses interactive digital communications to guarantee error free alignment of the transmitter and receiver, making the installation procedure 100% objective. Real time diagnostics from the field to a control station, via analogue 4 to 20 mA and RS485 communications, proactively alerts the operators to investigate the units, which can eliminate more costly routine inspections.

The latest surface mount electronics and opto-mechanics, have significantly reduced the size and weight of Searchline Excel, making it the world’s smallest open path IR gas detector. This will allow easier retrofitting into crowded areas of plant whilst making it less prone to vibration interference.

A robust waterproof (IP66 and IP67) stainless steel corrosion resistant body makes it eminently suitable to tolerate the extreme environmental conditions that pertain on the modern offshore or petrochemical plant.

The advances made in the new Searchline Excel herald a new era in the supply and operation of an OPGD system to match the stringent demands of the oil and gas industry, now and into the future.

With compliments:

Zellweger Analytics Limited
Hatch Pond House
4 Stinsford Road
Nuffield Estate
Dorset BH17 0RZ

Tel: + 44 (0) 1202 676161
Fax: + 44 ( 0) 1202 678011