Scaling data from the BP20 Absolute Pressure Sensor

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The BP-20 is a micromachined electronic absolute pressure sensor. This application note explains how to scale and how to interpret data from a BP-20 sensor used on an NRG Symphonie logger.

There are a variety of units of measure that are customarily used for pressure. The SI unit for Pressure is the Pascal (abbreviated Pa). The BP-20 is an “absolute pressure” or “barometric pressure” sensor. The customary metric unit for barometric pressure is the (now obsolete) bar. Barometric pressure varies around one bar, so the barometer reading is stated in millibars (abbreviated mb). Mercury barometers were traditionally used to measure barometric pressure, so the U.S. customary units for barometric pressure are inches of mercury (abbreviated inHg). Mercury expands and contracts with changes in temperature, so exact conversion factors from Pascals to inches of Mercury depend on the temperature. At 0 °C, the conversions are:

1 kilopascal = 10 millibars = 0.2953 inches of mercury.

In this note, these conversion factors are used to express barometric pressures in customary units as well as the SI units.