Rosemount 1199 - Calibrating a Two-Seal System With Elevated Zero

3-5
Calibration
FIGURE 3-3. Transmitter with Two-Seal System.
American Units 1. Calculate the amount of zero elevation by multiplying the
distance between the process connections (h) by the specific
gravity of the fill fluid (s
f
).
Zero Elevation = -(h)(s
f
)
= - (400 inches) (1.07 inH
2
O/inch) = - 428 inH
2
O
2. Calculate the span by multiplying the maximum height of the
process fluid (H) by the specific gravity of the process liquid (s
p
).
Span = (H)(s
p
)
= (350 inches) (0.9 inH
2
O/inch) = 315 inH
2
O
3. Calibrate the transmitter using the following equation:
Calibration = Zero Elevation to (Zero Elevation + Span)
= - 428 inH
2
O to (- 428 + 315 inH
2
O)
= - 428 inH
2
O to - 113 inH
2
O.
SI Units
Calibration:
Summary In this example a Model 3051CD Range 3, URL = 1,000 inH
2
O
(2,5 bar) or a Model 1151DP Range 5, URL = 750 inH
2
O
(1,9 bar) transmitter is required.
NOTE
Calibrating a Two-Seal System With Elevated Zero
(Transmitter Mounted Level With, Above, or Below the High Pressure Tap)
Given:
DC 704 fill fluid
(S
f
) = 1.07 in H
2
O/inch
(-h) = - 400 inches
(S
p
) = 0.9 in H
2
O/inch
(H) = 350 inches
H
1199-0160L
h
Transmitter
Given:
High Temperature
Silicone Oil fill fluid
(ρ
f
) = 1 070 kg/m
3
(-h) = -10 meters
(ρ
p
) = 900 kg/m
3
(H) = 8,5 meters
(g) = 9,81 m/s
2
Zero Elevation ρ
f
gh⋅⋅–=
1070–=981,
10
100
---------
mbar⋅⋅
1050
– mbar=
Span ρ
p
=gH⋅⋅
900= 981,
85,
100
---------
mbar⋅⋅
750 mbar=
4mA Zero Elevation
1050
mbar–==
20mA Zero Elevation Span+
1050
750 mbar+–==
300
mbar–=
1mbar
100
-----------------------1kgm
3
⁄()1m s
2
⁄()1m()⋅⋅1N m
2
⁄==
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