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WE100 Barometric Pressure Sensor
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4-20mA Output WE100 Barometric Pressure Sensor
Highly accurate Barometric Pressure Sensor covers a pressure range from 800 to 1100 mb. The barometric pressure indicator is fully temperature compensated within an operating range of -40 to 65 C. The sensor is mounted on 25' of marine grade cable, with lengths up to 500' available upon request. The sensor output is 4-20 mA with a two wire configuration
Product Description
WE100 Barometric Pressure Sensor produce a 4-20 mA output signal. 4-20 mA is an industrial standard signal for process control monitoring. Most PLCs (Programmable Logic Controller), RTUs (Remote Telemetry Unit), and data acquisition systems accept this signal directly. If the system only accepts voltage signals, the sensor output must be converted to a voltage signal by reading the voltage across a precision resistor in series with the signal wire. Since Ohms Law states that V = IR, if the 4-20 mA signal is dropped across a 250 ohm resistor, the output will be 1 to 5 volts DC. If the 4-20 mA signal is dropped across a 125 ohm resistor, the output will be halved to 0.5 to 2.5 VDC. The 4-20 signal wire is connected to the datalogger voltage input terminal. The resistor is placed between this input and the ground terminal of the datalogger's battery. The power (or voltage to the sensor) must be connected to positive battery terminal of the datalogger.
Readings
Two things affect the barometer's reading, the high or low air pressure caused by weather systems, and the air pressure caused by the station's elevation, or how high it is above sea level. No matter what weather systems are doing, the air's pressure decreases with height. If you're trying to draw a weather map of air pressure patterns, you need a way to remove the effects of the station's elevation. That is, you want to see what the pressure would be at the station if it were at sea level.
You need to calculate, sea-level pressure, which is defined as: A pressure value obtained by the theoretical reduction of barometric pressure to sea level. Where the Earth's surface is above sea level, it is assumed that the atmosphere extends to sea level below the station and that the properties of that hypothetical atmosphere are related to conditions observed at the station. To do this, you have to take into account the barometric reading at the station, the elevation above sea level, and the temperature.
Specifications
Output: 4-20 mA
Range: 800-1100 mb
Accuracy: +/-1% of full scale
Linearity/Hysteresis: +/-0.1%
Operating Voltage: 10-36 VDC
Current Draw: Same as sensor output
Warm Up Time: 3 seconds minimum
Operating Temp: -40 to +55c
Sensor Size: 3"x 2"x 1"
Weight: 0.13 lb.