Xylem WE100 BAROMETRIC PRESSURE TRANSMITTER - Manual (Page 5)

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IV. Barometric Pressure Sensor
a. Barometric Pressure sensor specifications.
Output: 4-19mA
Range: 800-1100 millibars
Accuracy: +1% of full scale
Operating Voltage: 10-36VDC
Current Draw: Same as sensor output
Warm Up Time: 3 seconds minimum
Operating Temperature: -40° to +55°C
Size of Probe: 3”x2”x1”
Weight: .13 lb.
b. The sensor is a two-wire sensor using the red wire for power and the
black wire for the output signal. Warning: Always connect the
sensor with the power turned off.
c. The barometric pressure sensor may be stored without any special
provisions. Place the sensor inside a bag to keep the sensor clean
and store on a shelf or hang it on a wall.
d. When you read a barometer the reading directly from it is the "station
pressure."
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