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Reference Manual
00809-0100-4808, Rev CA
June 2008
Rosemount 3051N
2-8
NOTE
Regardless of the range points, the Rosemount 3051N will measure and
report all readings within the digital limits of the sensor. For example, if the
4 and 20 mA points are set to 0 and 10 in H
2
O on a range code 1 Rosemount
3051N, and the transmitter detects a pressure of 25 inH
2
O, it digitally outputs
the 25 inH
2
O reading and a 250% of span reading. However, there may be up
to ±5.0% error associated with output outside of the range points.
Sensor Temperature The Rosemount 3051N contains a temperature sensor just above its pressure
sensor in the sensor module. When reading this temperature, keep in mind
that this is not a process temperature reading.
BASIC SETUP
Set Process Variable
Units
The PV Unit command sets the process variable units to allow you to monitor
your process using the appropriate units of measure. Select from the following
engineering units:
Set Output Activate the transmitter square root output option to make the analog output
proportional to flow. As the input approaches zero, the Rosemount 3051N
automatically switches to a linear output in order to ensure a more smooth,
stable output near zero. See Figure 2-5.
The transition from linear to square root is not adjustable. It occurs at 0.8% of
ranged pressure input or 8.9% of full-scale flow output.
From 0 percent to 0.6 percent of the ranged pressure input, the slope of the
curve is unity (y = x). This allows accurate calibration near zero. Greater
slopes would cause large changes in output for small changes at input. From
0.6 percent to 0.8 percent, the slope of the curve equals 42 (y = 42x) to
achieve continuous transition from linear to square root at the transition point.
HART Comm. 1, 1, 4
HART Comm. 1, 3, 2
•inH
2
O•bar
• inHg • mbar
•ftH
2
O • g/cm
2
•mmH
2
O • kg/cm
2
•mmHg •Pa
•psi •kPa
• torr • atm
•inH
2
O at 4 °C • mmH
2
O at 4 °C
HART Comm. 1, 3, 5