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The Model 851 is designed for years of stable performance in even the toughest environmental and media conditions, such as refineries, petrochemical facilities, paper & pulp plants, and waste water treatment facilities. Approvals include FM and CSA for both intrinsic safety and explosion-proof ratings. The Model 851 also meets NACE standards for offshore applications. A one year warranty is standard with every unit.
The small size and light weight of the Model 851 transmitter eliminates the need for complicated mounting hardware and mechanical supports, thereby reducing installation time substantially. The in-line connection permits simple fi eld wiring without the need for additional hardware, adding to the speed and ease of installation. Its slim profi le allows for mounting in places too tight for most other transmitters.
A 4-20 mA output is standard with a 12-40 VDC power supply. The Model 851 is bench adjustable, allowing for calibration of zero and span. With the cover sealed double O-ring assembly, this transmitter is weather proof and capable of direct spray, clean-in-place applications.
Features
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A miniature, low priced full-featured transmitter - just 1 lb. (450 grams)
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All welded 316 stainless steel construction and wetted parts (no aluminum)
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Ranges from 0-3 (0.2 bar) to 0-5000 psig (345 bar)
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±0.25% accuracy
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Zero and span adjustability
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Full 5:1 range turndown
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FM & CSA Explosion-proof and intrinsically safe
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4-20 mA output at 12-40 VDC
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Watertight cable or conduit connection optional
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1/2 in. NPT Female process connection or fl ush mount version
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Straight in-line construction for a slim profi le
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24 inch (61 cm) cable standard
Operation
The heart of the Model 851 pressure transmitter is a silicon piezoresistive sensing chip. This miniature micro-etched semiconductor gives an output proportional to the applied pressure. This chip is isolated from the process media by a stainless steel diaphragm. Silicone oil or other specifi ed fi ll fl uid is used to transmit the process pressure to the sensor.
A surface mount amplifi er board, enclosed in a sealed chamber, is used to convert the millivolt signal from the sensor to a calibrated 4-20 mA transmitter output. Transmitter electronics are surge and EMI protected.
Each transmitter is tested over both pressure and temperature ranges, and a thick fi lm compensator circuit is used to bring the output of the sensor into specifi cation. After compensation, every transmitter is tested a second time for pressure and temperature effects to ensure that it meets performance specifi cations.
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