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JJG 993-2018 English PDF

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JJG 993-2018: Electric Ventilation Psychrometers
Status: Valid

JJG 993: Evolution and historical versions

Standard ID	Contents [version]	USD	STEP2	[PDF] delivered in	Standard Title (Description)	Status	PDF
JJG 993-2018	English	399	Add to Cart	4 days [Need to translate]	Electric Ventilation Psychrometers	Valid	JJG 993-2018
JJG 993-2004	English	559	Add to Cart	3 days [Need to translate]	Verification Regulation of Electric Ventilation Psychrometer	Obsolete	JJG 993-2004

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Basic data

Standard ID	JJG 993-2018 (JJG993-2018)
Description (Translated English)	Electric Ventilation Psychrometers
Sector / Industry	Metrology & Measurement Industry Standard
Classification of Chinese Standard	A61
Word Count Estimation	17,199
Date of Issue	2018-06-25
Date of Implementation	2018-12-25
Older Standard (superseded by this standard)	JJG 993-2004
Regulation (derived from)	State Administration of Markets, Announcement No. 13 of 2018
Issuing agency(ies)	State Administration for Market Regulation

JJG 993-2018: Electric Ventilation Psychrometers

---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.
Electric Ventilation Psychrometers National Metrology Verification Regulations of the People's Republic Electric ventilation dry and wet table Published on.2018-06-25 2018-12-25 implementation State Administration of Markets issued Electric ventilation dry and wet meter verification procedures Replace JJG 993-2004 Focal Point. National Physical and Chemical Metrology Technical Committee Main drafting unit. China Institute of Metrology Participated in drafting unit. Jinan Changfeng Guozheng Technology Development Co., Ltd. This procedure entrusts the National Physical and Chemical Metrology Technical Committee to explain The main drafters of this procedure. Ren Changqing China Institute of Metrology Participate in the drafters. Yi Hong China Institute of Metrology Yang Ju China Institute of Metrology Zhang Wei Jinan Changfeng Guozheng Technology Development Co., Ltd.

Introduction (II) 1 Scope (1) 2 Overview (1) 3 Metrological performance requirements (1) 3.1 indication error (1) 4 General technical requirements (1) 4.1 Ordinary wet and dry watch (1) 4.2 Digital Dry and Wet Table (2) 5 measuring instrument control (2) 5.1 Verification conditions (2) 5.2 Verification project (4) 5.3 Verification method (4) 5.4 Processing of verification results (6) 5.5 Verification cycle (6) Appendix A Calculation of A value of wet and dry table (7) Appendix B Electric ventilation dry and wet table temperature indication error verification record format (8) Appendix C Electric ventilation dry and wet table humidity indication error verification record format (9) Appendix D Verification certificate/verification result notice page format (10)

Introduction

JJF1002 "Rules for the preparation of national metrological verification procedures", JJF1001 "General measurement terms and definitions" A basic series of specifications that support the revision of the procedures. Compared with JJG 993-2004, in addition to editorial changes, the main technical changes of this specification are as follows. --- Temperature range. modified to (5~50) °C, humidity range. (10~95)% RH. (see range 1); ---Working standard standard wet bulb thermometer does not specify the absolute value of the error and the difference between the dry and wet thermometer indication errors Value (see Table 1); --- Remove first-class and second-class mercury thermometers; standard digital thermometers at work level (see Table 2); humidity The standard increases the maximum allowable error column (see Table 3); --- Increase the temperature and humidity standard box for the main supporting equipment (see Table 4); --- Temperature and humidity equipment are listed in Table 4, and the indicators are more detailed; --- Humidity check points have been increased or decreased (see Table 6). The previous versions of this procedure are released as follows. ---JJG 993-2004. Electric ventilation dry and wet meter verification procedures

1 Scope

This procedure applies to the temperature measurement range (5~50) °C, humidity measurement range (10~95)% RH electric pass The first test, follow-up test and in-use check of the air-drying wet watch.

2 Overview

Electric ventilation wet and dry watch (hereinafter collectively referred to as wet and dry watch) includes two types of digital wet and dry watch and ordinary dry and wet watch. The wet and dry watch consists of two thermometers, a ventilator, a water cup and a radiation protection tube. The digital wet and dry watch also includes Temperature and humidity display. Its principle block diagram is shown in Figure 1. Wet and dry watch Dry bulb thermometer Wet bulb thermometer → temperature measuring Humidity value Calculate or display Figure 1 dry and wet table block diagram The wet and dry watch works on the principle that at a constant ventilation speed, air flows through the surface of the dry and wet bulb thermometer due to The wet bulb thermometer has a wet gauze, and the surface moisture vaporizes to lower the wet bulb temperature, and the lowered temperature value is the wet bulb temperature. degree. After the dry and wet bulb temperature is measured by the dry and wet bulb thermometer, the relative humidity value is calculated according to the dry and wet table equation.

3 Metrological performance requirements

3.1 indication error The dry and wet indication values are shown in Table 1. Table 1 Dry and wet indication value error Dry and wet table level 2 standard working level Dry bulb thermometer indication error/°C ±0.08 ±0.3 Wet ball thermometer indication error/°C ±0.08 - Dry and wet thermometer indication error The absolute value of the difference/° C ≤0.1 - Relative humidity /%RH ≤2.0 ≤5.0 Note. 1. The wet bulb thermometer indicates the temperature indication when the wet ball gauze sleeve is not installed. 2. Ordinary wet and dry watch can not be used as a humidity secondary standard.

4 General technical requirements

4.1 Ordinary wet and dry watch 4.1.1 The shape of the sensor should be intact and its outer surface should be polished or blackened. 4.1.2 The dry and wet bulb thermometer of the sensor shall be concentric with its radiation protection tube (layer).

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