The technique is developed in KSTU of A.N. Tupolev on faculty "Standardizations, certifications and technological management" according to the established requirements in accordance with GOST Р 8.563-96.
Techniques of performance of measurement.
The technique is intended for measurements performance of concentration of the positive and negative air ions contained in 1cm3 of air under normal conditions, with the help of the air ion counter "Sapphire-3К" (State register № 18295-99).
The technique provides performance of measurements for concentration of air ions in a range from 2*102 up to 2*106 cm with a relative error not more than 0,4 +0,01*[(nk/nx)-1], where nk is final value of a sub range limit in measurements of the counter; nx - indications of the counter.
The counter has four sub ranges:
- 1st sub range from 2*102 to 2*103 cm-3
- 2nd sub range from 2*103 to 2*104 cm-3
- 3rd sub range from 2*104 to 2*105 cm-3
- 4th sub range from 2*105 to 2,5*106 cm-3
The technique needs the reference counter maintained under normal conditions according to GOST 14763-78. The technique is based on application of GOST 8.207-76 regulating direct measurements with repeated independent measurements. When doing statistical processing of the group of observations results the following operations are carried out:
- - Choose number of results of supervision (indications of the counter) n, then measurements (n> 50, 50> n> 15, n <15) will be made;
- - Take n readings from the indicator board of the counter;
- - Check the hypothesis about normal distribution of observations;
- - Exclude rough observation errors according to the instructions given in GOST 11.002-73;
- - Calculate the result of measurement using the formula
Where - are observation results without rough errors.
- Calculate the measurement result as below
- Calculate an estimation of the confidence bound for the mean-square error of measurement results, using the formula
Where - is a Student's coefficient depending on chosen confidential probability P and number of measurement results;
- Adjust the measurement results in accordance with GOST 8.011-72.
- If the confidential error is symmetric, then the measurement results are represented in the form
When P=: %.
The author of the article - Aydar Tuktagulov (Sapphire Company www.ionization.ru)