Emerson 3051N User Manual

Page of 100
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