1.4 The object to be measured: measurement range (0 ~ 100)%mol/mol, the display value error ± 1.O%F.S
2 mathematical model
Passed a certain concentration of the standard gas, equilibrated to read the indicated value of the instrument being checked. Repeat the measurement 3 times, the arithmetic mean of the readings and the standard gas actual value of the difference with the range of the ratio, that is, the error of the value of the instrument being checked.
The mathematical model can be regarded as:
Where:
-The error of the instrument under test;
-The value of the instrument under test;
-The concentration of the standard gas;
-Other influencing factor components.
R-Range of the instrument under test
3 Find the variance according to the mathematical model
Given that the inputs are independent of each other,
the variance relationship is:
Given that the modulus of each sensitivity coefficient is 1,
there are:
4 Calculation of the uncertainty of each standard component
4. p>4.1 Class A standard uncertainty components
The uncertainty of the input quantity is determined by the repeatability of the instrument being measured under the same conditions, repeated many times, and is evaluated using class A. The uncertainty of the input quantity is determined by the repeatability of the instrument being measured under the same conditions, repeated many times.
On a range of 30μmol/mol carbon monoxide infrared gas analyzer, select 11.2μmol/mol standard concentration of carbon monoxide gas, repeat the measurement under the same conditions for 10 times, that is, n = 10, to get the measured value as follows:
11.0 10.9 10.9 10.8 10.9 10.9 10.9 11.0 11.0 10.9
The arithmetic mean value is 10.92
According to Bessel's formula, the standard deviation of a single measurement is
0.099
In the usual practical measurement, three consecutive measurements are made under the repetition condition, and the arithmetic mean value is taken as the result of the measurement, then the standard uncertainty is
0.057μ mol/mol
4.2 Standard uncertainty component introduced by the standard apparatus
The carbon monoxide standard gas with a standard concentration of 11.2 μmol/mol is provided by the National Standard Substance Research Center, which is a national level standard substance, and its relative extended uncertainty is 1%, k=2, and it is evaluated by using category B.
0.056μmol/ mol
4.3 Standard Uncertainty Components Introduced by Other Influencing Factors
4.3.1 Uncertainty Components of Ambient Temperature
In the checking temperature of (15~35)℃±2℃, the limit error introduced to the instrumental value was obtained from the experiment
The uncertainty components of ambient temperature are as follows