JJG 499-2021 English PDF

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JJG 499-2021: Precision Dew Point Hygrometers
Status: Valid

JJG 499: Historical versions

Standard ID	USD	BUY PDF	Lead-Days	Standard Title (Description)	Status
JJG 499-2021	439	Add to Cart	4 days	Precision Dew Point Hygrometers	Valid
JJG 499-2004	599	Add to Cart	3 days	Verification Regulation of Precision Dew-point Hygrometers	Obsolete
JJG 499-1987	559	Add to Cart	4 days	Verification Regulation of Precision Dewpoint Hygrometer	Obsolete

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Basic data

Standard ID: JJG 499-2021 (JJG499-2021)
Description (Translated English): Precision Dew Point Hygrometers
Sector / Industry: Metrology & Measurement Industry Standard
Classification of Chinese Standard: A61
Word Count Estimation: 19,112
Issuing agency(ies): State Administration for Market Regulation

JJG 499-2021: Precision Dew Point Hygrometers

---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Precision Dew Point Hygrometers People's Republic of China National Metrological Verification Regulations Precision Dew Point Meter Published on 2021-12-28 2022-06-28 Implementation Released by the State Administration for Market Regulation Verification Regulations of Precision Dew Point Meter Replacing JJG 499-2004 Focal Point. National Technical Committee of Physical Chemistry and Metrology Main drafting unit. China Institute of Metrology Shanghai Institute of Metrology and Testing Technology Aviation Industry Beijing Great Wall Metrology and Testing Technology Research Institute Participating in the drafting unit. The Fifth Third Research Institute of China Ordnance Industry Group Jiangsu Institute of Metrology This regulation is entrusted to the National Technical Committee of Physical Chemistry and Metrology to be responsible for the interpretation The main drafters of this regulation. Yi Hong (China Institute of Metrology) Zhang Wendong (Shanghai Institute of Metrology and Testing Technology) Lv Guoyi (Beijing Great Wall Metrology and Testing Technology Research Institute of Aviation Industry) Participating drafters. Li Zhanyuan (China Institute of Metrology) Zhang Xuefan (The Fifth Third Research Institute of China North Industries Group Corporation) Zheng Shengqing (Jiangsu Institute of Metrology) Ren Changqing (China Institute of Metrology)

Table of contents

Introduction (Ⅱ) 1 Scope(1) 2 References (1) 3 Overview(1) 4 Measurement performance requirements (2) 5 General technical requirements (2) 5.1 Appearance(2) 5.2 Dew point sensor measuring chamber and refrigerator(2) 5.3 Relative Humidity Calculation Function Check(2) 6 Measuring Instrument Control(2) 6.1 Verification Conditions (2) 6.2 Verification items (4) 6.3 Verification method (4) 6.4 Processing of Verification Results (6) 6.5 Verification Period(6) Appendix A Calculation of Dew Point Meter for Relative Humidity Measurement(7) Appendix B Correction calculation of dew point temperature under different pressures (9) Appendix C Example of Uncertainty Evaluation of Measurement Results of Indication Error of Secondary Precision Dew Point Meter (10) Appendix D Verification Raw Record Format (12) Appendix E Verification Certificate Inner Page Format (13) Appendix F Inner Page Format of Verification Result Notification (14)

Introduction

This regulation is based on JJF1001-2011 "General Metrology Terms and Definitions", JJF1002-2010 "National Metrology Terms and Definitions" Verification Regulations Compilation Rules and JJF1059.1-2012 Measurement Uncertainty Evaluation and Representation. This regulation is a revision of JJG 499-2004 "Precision Dew Point Meter". Compared with JJG 499-2004, except for editing In addition to the editorial modifications, the main technical changes are as follows. --- Deleted the chilled mirror precision dew point meter for dew point detection based on the surface acoustic wave principle; ---Expanded the verification range of the precision dew point meter, added the repeatable technical index items, and specified the maximum allowable Error and repeatability technical requirements (see Chapter 4); --- Added relative humidity calculation function check (see 5.3); --- Added the corresponding technical requirements for the pipes and connection methods of the measuring gas system (see 6.1.5, 6.3.4.2); ---Optimize the selection method of verification points, and increase the repeatability calculation formula; --- Added the recommended calculation formula for saturated water vapor pressure and its enhancement factor (see Appendix A); --- Added Appendix A "Calculation of Dew Point Meter for Relative Humidity Measurement" (see Appendix A); --- Added Appendix B "Calculation of Correction of Dew Point Temperature under Different Pressures" (see Appendix B). The previous versions of this regulation have been released as follows. ---JJG 499-2004; ---JJG 499-1987. Verification Regulations of Precision Dew Point Meter

1 Scope

This regulation is applicable to the first phase of the precision dew point meter which adopts the principle of water vapor pressure phase balance and adopts photoelectric automatic detection of refrigerated mirror. Checks, subsequent checks, and in-use checks.

2 Reference documents

This procedure cites the following documents. JJF1012-2007 Terms and Definitions of Humidity and Moisture Measurement BS1339-1.2002 Humidity Part 1.Terms, Definitions and Formulas (Humidity-Part 1. For dated citations, only the dated version applies to this Regulation; for undated citations The latest version (including all amendments) applies to this regulation.

3 Overview

The balanced precision dew point meter (hereinafter referred to as the dew point meter), which automatically detects the dew point temperature of the cooling mirror, is a thermoelectric Refrigeration devices such as refrigerators (composed of devices that produce cooling capacity by the thermoelectric effect of semiconductors) are used for dew point sensors (including mirrors). surface, light-emitting devices and light-receiving devices, etc.) the mirror surface is cooled down, so that the water vapor in the sample gas condenses on the mirror surface; The device collects the reflected light signal of the mirror, and makes the condensation (or frost) on the mirror and the water in the gas through the automatic control circuit. The vapor is in a phase equilibrium state; the dew condensation temperature of the mirror is accurately measured with a platinum resistance temperature sensor, so as to obtain the dew condensation temperature of the gas. point temperature. As shown in Figure 1, the gas sweeps across the mirror as it passes through the dew point sensor measurement chamber. When the mirror temperature is higher than the dew of the gas When the temperature reaches a certain temperature, the mirror surface is in a dry state. At this time, the transmitted light signal and received light signal of the dew point sensor are controlled by The control loop compares and amplifies, and drives the thermoelectric cooler to cool the mirror surface; when the mirror surface temperature drops below the dew point temperature of the sample gas At this time, condensation begins on the mirror surface, and the optical signal collected by the optical receiver changes. This change is compared by the control loop, After amplification, the excitation of the thermoelectric cooler is adjusted to reduce the cooling power, and finally the mirror temperature is kept at the dew point temperature of the sample gas. degree. Figure 1 Schematic diagram of the measurement principle of the dew point meter ......

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