GB/T 8304-2013Tea -- Determination of moisture content (English PDF)

Foreword

This standard was drafted in accordance with GB/T 1.1-2009 given rules.

This standard replaces GB/T 8304-2002 "Determination of tea points." This standard compared with GB/T 8304-2002, the main technical change as follows.

--- The principle of the principles of moisture determination made appropriate complementary;

--- Instruments and appliances added to the sample container, quality glass baking dish;

--- Repeatability. the difference between the two measurement results, moisture per 100g sample should not exceed 0.2g, modified to repeat the same conditions under the absolute difference between the measurement results of the sample must not exceed 5% of the arithmetic mean.

This standard uses redrafted law revision using ISO 1573. 1980 "Tea at 103 °C Determination of mass loss." This standard and ISO 1573:1980 compared to the main technical differences are as follows.

--- Modify using ISO 1573. 1980 as the first law of this standard;

--- Increased 120 °C drying method (rapid method) as the second law of this standard;

--- Measured in the sample drying time constant weight in water method 103 °C ± 2 °C modified to 4h from 6h;

--- Repeatability. the difference between the two measurement results, moisture per 100g sample should not exceed 0.3g, modified to repeat the same conditions under the absolute difference between the measurement results of the sample must not exceed 5% of the arithmetic mean;

--- Remove the ISO 1573. 1980, Chapter 9 test reports;

--- Remove the drying process considerations.

This standard also made the following editorial changes.

--- Remove the ISO 1573. 1980 Foreword;

--- Remove the ISO 1573. 1980 introduction.

The standard proposed by China Federation of Supply and Marketing Cooperatives.

This standard by the National Standardization Technical Committee of tea (SAC/TC339) centralized.

This standard was drafted. China Federation of Supply and Marketing Cooperatives Hangzhou Tea Research Institute, the National Tea Quality Supervision and Inspection Center, Xiamen Huaxiang Garden Tea Co., Ltd..

1 Scope

This standard specifies the tea moisture determination instruments and appliances, and the result of the calculation method step measurement.

This standard applies to the determination of tea water.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein Member. For undated references, the latest edition (including any amendments) applies to this document.

GB/T 8302 sampling Tea (GB/T 8302-2013, ISO 1839. 1980, NEQ) GB/T 8303 Tea grated dry matter content of the sample preparation and measurement (GB/T 8303-2013, ISO 1572. 1980, MOD)

3 Terms and Definitions

The following terms and definitions apply to this document.

Water moisturecontent Under atmospheric conditions, the sample was heated to a predetermined temperature by the mass loss of the constant weight.

Principle 4

Samples at 103 °C ± 2 °C in electric oven heated to a constant weight, weigh, and calculate the mass loss of the samples is water.

5 Instruments and appliances

5.1 Sample container. the clean, dry, dark, airtight glass or other material does not react with the sample prepared; the size to be able to fill mill Crushed sample is appropriate.

5.2 Quality aluminum or glass baking dish. a cover, an inner diameter of 75mm ~ 80mm.

5.3 blast electric oven. temperature 103 °C ± 2 °C.

5.4 dryer. containing more effective desiccant.

5.5 Analysis of balance. a sense of the amount of 0.001g.

6 Operation