horiba U-51, Инструкция по эксплуатации

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6 Reference
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6.10 Depth (DEPTH) measurement
6.10.1 Principle of depth measurement
For the U-50 series, depth measurement can be made through use of a pressure gauge. The
principle of the depth measurement uses the relation between depth and pressure.
Although the measurement with the depth sensor is affected by atmospheric pressure, the
depth sensor, however, makes zero-point adjustments through the automatic calibration
before measurements.
6.10.2 Influence of temperature and calibration
The depth sensor depends greatly on temperature. For a wide difference between the
temperature at which the sensor has been automatically calibrated and the temperature of the
measurement sample, the sensor can make depth measurements with a higher accuracy by
the following method:
1. Immerse the depth sensor of the sensor probe in the sample.
2. Keep the sensor immersed in the sample for about 30 minutes until the
temperatures of the sensor and the sample are the same.
3.
Then make the zero calibration of the sensor manually.
6.11 Oxidation reduction potential (ORP) measurement
6.11.1 Principle of ORP measurement
ORP is an abbreviation for oxidation-reduction potential. ORP is the energy level (potential)
determined according to the state of equilibrium between the oxidants (M
Z+
) and reductants
M
(Z

N)+
that coexist within a solution.
If only the solution, forming the ORP measuring system shown in Fig. 8. The difference of
potential between two electrodes is generally expressed by the following equation.
E: Electric potential E
0
: Constant R: Gas constant T : Absolute temperature
n: Electron count F : Faraday constant a : Activity
Fig. 8 Measuring mV
For example, for a solution in which trivalent iron ions coexist with bivalent iron ions, equations
1 and 2 would be as follows.
M
Z+
+ ne

⇔
M
(Z

N)+
… (1)
E = E
0

RT
nF
a
M
(z-n)+
a
M
z+
ln
… (2)
E
Potentiometer
R
Pt
(Au)
Fe
3+
+ e

⇔
Fe
2+
… (1)
E = E
0

RT
F
a
Fe
2+
a
Fe
3+
ln
… (2)