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

Model 1199 Diaphragm Seal Systems Manual
3-4
FIGURE 3-2. Transmitter Mounted Above a Single Seal.
American Units 1. Calculate the amount of zero elevation by multiplying the height of
the transmitter above the process connection (-h) by the specific
gravity of the fill fluid (s
f
).
Zero Elevation = (-h)(s
f
)
= (-30 inches) (1.9 inH
2
O/inch) = -57 inH
2
O
Step 2 2. Calculate the transmitter span by multiplying the maximum height
of the process fluid (H) by the specific gravity of the process liquid
(sp).
Span = (H)(s
p
)
= (120 inches) (1.1 inH
2
O/inch) = 132 inH
2
O
Step 3 3. Calibrate the transmitter using the following equation:
Calibration = Zero Elevation to (Zero Elevation + Span)
= -57 inH
2
O to (-57 + 132 inH
2
O)
Step 4 = -57 inH
2
O to 75 inH
2
O
SI Units
Calibration:
Summary Therefore, in this example, a Model 3051CG Range 2,
URL = 250 inH
2
O (620 mbar), Model 1151 Range 4,
URL = 150 inH
2
O (375 mbar), or Model 2088 Range 0,
URL = 220 inH
2
O (550 mbar) transmitter is required.
NOTE
Calibrating a One-Seal System With Elevated Zero
(Transmitter Mounted Above the High Side Tap)
Transmitter
-h
Given:
Inert fill fluid
(s
f
) = 1.9 in H
2
O/inch
(-h) = -30 inches
(s
p
) = 1.1 in H
2
O/inch
(H) = 120 inches
H
Given:
Inert fill fluid
(r
f
) = 1850 kg/m
3
(-h) = 0,75 m
(r
p
) = 1 100 k/m
3
(H) = 3 m
(g) = 9,81 m/s
2
20 mA
4 mA
Zero Elevation ρ
f
gh⋅⋅–=
1850 9 81,
0
75
,
100
------------
mbar⋅⋅–=
136 mbar–=
Span ρ
p
gH⋅⋅=
1100 9 81,
3
100
---------
mba
r
⋅⋅=
324 mbar=
4mA Zero Elevation
136 mbar
–==
20mA Zero Elevation Span+
136 324 mbar
+–==
188 mbar
=
1mbar
100
-----------------------1kgm
3
⁄()1m s
2
⁄()1m()⋅⋅1N m
2
⁄==
1199-0160k
Step 2
Step 3
Step 1
Step 2