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JJG 757-2018

Chinese Standard: 'JJG 757-2018'
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JJG 757-2018English429 Add to Cart Days<=4 Laboratory Ion Meters Valid JJG 757-2018
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Standard ID JJG 757-2018 (JJG757-2018)
Description (Translated English) Laboratory Ion Meters
Sector / Industry Metrology & Measurement Industry Standard
Classification of Chinese Standard A55
Classification of International Standard 17.220.20
Word Count Estimation 21,264
Date of Issue 2018-12-25
Date of Implementation 2019-06-25
Older Standard (superseded by this standard) JJG 757-2007
Drafting Organization China Testing Technology Research Institute
Administrative Organization National Physical and Chemical Metrology Technical Committee
Regulation (derived from) State Administration of Markets, Announcement No.34 of 2018
Issuing agency(ies) State market supervision and administration
Summary This standard is applicable to the first verification, subsequent verification and in-use inspection of the laboratory universal ion meter for measuring the ion activity in the solution by the electrode potential method.

JJG 757-2018
Laboratory Ion Meters
National Metrological Verification Regulation of the People's Republic of China
Laboratory ion meter
2018-12-25 released
2019-06-25 implementation
Issued by the State Administration for Market Regulation
Laboratory ion meter verification regulations
Replace JJG 757-2007
Focal point. National Technical Committee of Physical Chemistry Metrology
Main drafting unit. China Academy of Testing Technology
Participated in the drafting unit. Hulunbuir Product Quality Measurement Testing Institute
This regulation entrusts the National Technical Committee of Physical Chemistry Metrology to interpret
The main drafters of this regulation.
Yuan Li (China Academy of Testing Technology)
Xie Qi (China Academy of Testing Technology)
Shao Zhixin (China Academy of Testing Technology)
Participating drafters.
Xijile (Hulunbuir Product Quality Measurement Testing Institute)
table of Contents
Introduction (Ⅱ)
1 scope (1)
2 Overview (1)
3 Measurement performance requirements (1)
4 General technical requirements (2)
4.1 Appearance and preliminary inspection (2)
4.2 Power-on inspection (2)
5 Measuring instrument control (2)
5.1 Verification conditions (2)
5.2 Equipment for verification (2)
5.3 Certified reference materials (3)
5.4 Verification items (3)
5.5 Verification method (4)
5.6 Verification results (7)
5.7 Verification cycle (7)
Appendix A Preparation method of fluoride ion standard solution (8)
Appendix B Original Record Format of Laboratory Ion Meter Verification (9)
Appendix C Inner Page Format of Verification Certificate/Notification of Verification Results (14)
This regulation is based on JJF1001-2011 "General Metrology Terms and Definitions", JJF1002-2010 "National Metrology
The "Verification Regulations Compilation Rules" is the basis and basis for revising the JJG 757-2007 "Ion Meter".
Compared with JJG 757-2007 "Ion Meter", in addition to editorial changes, the main technical content has the following changes.
---The name of the procedure was changed to "Laboratory Ion Meter";
---Deleted the measurement performance requirements of class 0.2, class 0.02 and class 0.05 laboratory ion meters;
---Insulation resistance, activity indication error, output error, stability, power supply voltage adaptability, and
Pointer type analog adjustment of the slope regulator range, equipotential regulator adjustment range, positioning regulator adjustment range, etc.
--- Deleted Appendix A, Appendix B, Appendix C, and Appendix D of the original regulations;
---Modified the environmental conditions for verification (see 5.1);
---Modified the requirements for verification equipment and certified reference materials (see 5.2, 5.3);
---Modified the measurement performance requirements (see Table 1);
---Modified the verification circuit connection diagram (see Figure 1);
---Modified the meter display value error (original display value error), meter input current (original input current), meter input
Impedance (original input impedance), meter reading repeatability (original repeatability), meter pX temperature compensation error (original temperature compensation)
Test methods for items such as compensator error) and temperature indication error (temperature measurement error) (see 5.5.4~5.5.9);
---Increase the instrument pX indication error and instrument pX indication repeatability test method and measurement performance requirements (see
5.5.10 and Table 1);
---The preparation method of Appendix A fluoride ion standard solution has been added.
Previous releases of this regulation.
---JJG 757-2007;
---JJG 757-1991.
Laboratory ion meter
1 Scope
This regulation is applicable to the initial verification and post-examination of laboratory general ion meters for measuring ion activity in solution by electrode potential method.
Continued verification and in-use inspection.
2 overview
Laboratory ion meter (hereinafter referred to as instrument) is an electrochemical analyzer used to measure ion activity in solution
The device is mainly composed of two parts. an electric meter and a measuring electrode. The electricity meter consists of an impedance converter, a potential amplifier, and a function regulator
It is composed of display and measuring electrode including ion selective electrode and reference electrode. Use instrument to measure ion content in solution
When using the comparative method to measure, first measure the battery composed of standard solution, ion selective electrode and reference electrode
Calibrate the ion meter, and then use the same pair of electrodes to measure the solution to be tested, the electromotive force of the battery can be directly
The connection is displayed as a potential value, or it can be displayed as pX or concentration after conversion by an electric meter.
The relationship between the electromotive force E of the battery and the ion activity αx in the measured solution is.
nF lgαx
E0---starting potential, V;
R---gas constant, 8.3144598 (48) J·K-1·mol-1;
T---thermodynamic temperature, K;
n---the charge number of the ion;
F---Faraday constant, 96485.33289 (59) C·mol-1.
E0 includes the standard electrode potential, reference electrode potential, and liquid junction potential of the ion-selective electrode.
It is called the theoretical slope of the electrode, expressed by k; if -lgαx is expressed by pX, then the formula (1) is.
E=E0±kpX (2)
When the measured ion is a positive ion, use "-" before k; when the measured ion is a negative ion, use "" before k.
The initial potential E0 is adjusted by the standard solution and ion meter to eliminate.
E=±kpX (3)
In solution, the relationship between ion activity and ion concentration is.
αx=γx·mx (4)
γx-activity coefficient;
mx---Ion concentration.
3 Measurement performance requirements
The measurement performance requirements of the instrument are shown in Table 1.
Related standard:   JJG 588-2018  JJG 183-2017
Related PDF sample:   JJG 376-2007  JJG 1148-2018
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