Improved barometric measurement by scaling pressure transmitter output

8th July 2007

To improve measurement performance of barometric measurements of a pressure transmitter, the 4-20mA output signal is scaled from 800 to 1200mbar absolute rather than the more usual 0 to 1200 mbar absolute.

Typically a pressure transmitter is calibrated at 5 points over its range to ensure it is inside specification.  If a 0 to 1 or 1.5 bar absolute range is used to measure the barometric pressure you will only be using the pressure transmitter over a narrow part of its range and most likely only 1 or 2 of the calibration points will be inside the barometric pressure range.

By scaling the current loop output signal of the absolute pressure transmitter to the barometric pressure range each of the 5 calibration points which are equally spaced between the lowest and highest measured pressure will be inside the region of barometric measurement and thus will provide a more robust verification of the pressure transmitter’s performance.

The effective increase in signal output over the barometric pressure range also allows the most use of the bit resolution available from the instrument measuring the output signal from the barometric pressure transmitter.

The TSA pressure transmitter is an example of a sensor which has the option for a pressure range with a 4-20mA output signal scaled from 0.8 to 1.2 bar absolute for barometric pressure readings.


Related Products

TSA product page for pdf downloads and price requests

Atmospheric pressure sensors

Other types of barometric instrumentation

Weather stations


Associated Topics

Gauge and absolute pressure explained

Vacuum measurement with a gauge or absolute sensor


Resources

Barometric conversion table

Pressure transmitter technical glossary

Pressure calculator


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