Yokogawa DM8C/VD6 Liquid Density Analyzer - Manual (Page 53)

< 4. OPERATION >
4-11
IM 12T03A01-02E
(Note 2) The density value after calibration doesn’t always coincide with the density of the standard
solution 1 even if they are compared in the same temperature.
Especially when the solution temperature during calibration largely different from the reference
temperature an error is apt to occur.
However, the error is usually within allowable range, if it is too large, examine each set value.
(8) The fi rst calibration is fi nished by (7). Then, use the standard solution 2 carry out the second
calibration whose procedure is same as the fi rst calibration. Repeat the operations of (1) to (7).
For the calibration computation, set the function No. to ‘A’ (CAL-2 display fl ashes seven times).
When the second calibration is fi nished, purge the standard solution from the vibrator and screw
the blind plug into the pouring port, fully close the needle valves “NV2” and “NV3” and remove the
connected air pipe.
4.4.2 Calibration with a Sample
Calibration with sample liquid should be made according to the following procedure.
(1) Sample the measuring liquid which is measured by a hydrometer. Sampling should be made
when the liquid density is stable.
(Note) The density of the sample liquid should not change between sampling the liquid and
fi nishing the fi rst calibration.
(2) Measure the density using the hydrometer and the temperature of the sampled liquid.
Examine the temperature coeffi cient if it is not known. Using densities at high temperature
(reference temperature + approx. 5 °C) and low temperature (reference temperature - approx. 5
°C), the temperature coeffi cient should be calculated as following.
Temperature coeffi cient (g/cm 3 /°C) =
(Density at high temperature – Density at low temperature)
/Difference between high and low temperatures
(Note 1) The density values should be those at the reference temperature as far as possible.
(3) Set the mode transfer switch of the converter to “CAL” and input the data corresponding to
function No. ‘3’, ‘4’ and ‘5’.
(4) For specify the fi rst calibration computation, select the function No. ‘6’ and press “SET” key.
‘CAL-1’ display fl ashes during computation and the density at the reference temperature is
displayed after computation.
Confi rm that the density value is almost the same as that of measured at (2).
(5) Before carrying out the second calibration, change the density of the measuring solution in the
sampling unit. Perform the operations of (1) to (4). In the operation corresponding to (3), input
the data to function No. ‘7’, ‘8’ and ‘9’. In the operation corresponding to (4), use the function No.
‘A’ to specify calibration computation.
4.4.3 Calibration Error
If an error indication (E005 in the fi rst calibration or E006 in the second calibration) is displayed when
calibration computation fi nishes, examine the data input to function No. ‘3’, ‘4’, ‘5’, ‘7’, ‘8’ or ‘9’ and
repeat the computation using the incorrect data.