Calibration Of Specific Gravity Meter - GE Masoneilan 12420 Instruction Manual & Safety Manual

7.4. CALIBRATION OF SPECIFIC GRAVITY METER

This adjustment is made at the factory for complete instruments. The specific gravity function [SG METER] is very useful in
performing on site new calibrations, simulations with or without liquid and direct reading of specific gravity of liquids on the
application.
The Specific Gravity Meter function is factory calibrated at a specific gravity of 1.0 for a complete instrument only if the
displacer volume is lower than 1270 cm
For an instrument delivered alone with a torque tube, the Specific Gravity Meter function is factory calibrated at a S.G.
1.0 for a displacer with 907 cm
If actual displacer characteristics differ from these values, recalibration is required and is possible only if displacer
volume is lower than 1270 cm
Reading of the specific gravity of a liquid is possible only when displacer is fully immersed into the liquid and if [SG
METER] function has been previously calibrated.
a. Into the [ADV SETUP] menu, enter the [SGM CALIB] sub-menu. See Appendix C.
b. Enter the Specific Gravity of Calibration of the S.G. Meter [SG CALIB] =1.0
c. L
[ZERO]
OW LEVEL
c1. Attach a set of weights to the torque arm equivalent to the true displacer weight (i.e. 1362 g for a standard displacer) to
simulate the low level or empty the displacer chamber.
c2. Enter and validate the [ZERO]: the [LEVEL:%] value indicated on the display must equal 0.0%. If not, restart the
procedure until very close to this value. See Appendix C.
d. H
[SPAN]
IGH LEVEL
d1. Attach a set of weights to the torque arm equivalent to the apparent displacer weight in high level position with
Specific Gravity of Calibration [SG CALIB] 1.0 or fill the displacer chamber up to the high level position. Stabilise the
displacer (or weights).
Parameter name
Displacer weight
Displacer volume
Fluid specific gravity
Actual volume and weight of the displacer can be read using HART communication (if data have been previously saved into
the 12400 instrument memory). Otherwise actual volume of the displacer is marked on the firm plate and displacer weight
can be measured by weighting of it.
d2. Enter and validate the [SPAN]: the [LEVEL:%] value indicated on the display must equal 100.0%. If not, restart the
procedure until very close to this value. See Appendix C.
e. Press the * button when [SAVE] is displayed to validate the [ZERO] and [SPAN] settings.
f. To check if the specific gravity meter calibration has been correctly done, go to VIEW DATA menu, then [SG METER] to read
values corresponding to low and high references.
® 2014 General Electric Company. All rights reserved.
and the weight is 1362 g.
3
volume and 1362 g weight.
3
and if service specific gravity x displacer volume is lower than 1270.
3
S.I Units English Units
g lbs
cm 3 in 3
CAUTION:
Displacer Apparent Weight for REF H=
Displacer Actual Weight - (Displacer Actual Volume X [SG CALIB])
i.e. 1362 – 907 x 1 = 455 g for a standard displacer and water
Masoneilan 12400 Series Transmitter/Controller Instruction Manual | 33