GB/T 18915.2-2013Coated glass－Part 2: Low emissivity coated glass (English PDF)

3.1 Emissivity

The ratio between the radiant exitance of heat radiators and the radiant exitance of Planck radiators at same temperature.

5.1 Requirements and test methods of low emissivity coated glass

The corresponding chapters of requirements and test methods are shown in Table 1.

5.4 Optical properties

Low emissivity coated glass's optical properties include. ultraviolet transmittance, visible light transmittance, visible light reflectance, sunlight direct transmittance, sunlight direct reflectance, and sunlight total transmittance. The requirements shall comply with the specifications of Table 3.

5.5 Color uniformity

Color uniformity of low emissivity coated glass is represented by CIELAB uniform color space delta Eab. Its chromatic aberration shall be less than 2.5.

5.6 Emissivity

Emissivity of low emissivity coated glass refers to the hemispherical emissivity of coats at a temperature of 293K, and in a wavelength range of 4.5µm~25µm.

Emissivity of offline emissivity coated glass shall be less than 0.15; emissivity of online emissivity coated glass shall be less than 0.25.

5.9 Alkali resistance

The absolute value of the difference between specimens' visible light transmittance before test and after test shall not be greater than 4%.

6.2 Determination of curvature

6.3 Determination of appearance quality

TAKE the products as specimens. DETERMINE according to the method specified in GB/T 18915.1.

6.4 Determination of optical properties

6.4.1 Sampling methods

For non-tempered low emissivity coated glass, SELECT three pieces of products randomly from each batch of products. And CUT 100mm×100mm specimens in the same position of the product's central region, totaling three pieces of specimens.

6.5 Determination of color uniformity

Color uniformity of low emissivity coated glass is determined according to the method specified in GB/T 18915.1.

6.6 Determination of emissivity

6.7 Determination of abrasion resistance

6.7.1 Sampling methods

SELECT three pieces randomly in the same batch of products. CUT 100mm×100mm specimens in each piece of products, totaling three pieces. For tempered and semi-tempered low emissivity coated glass, CUT specimens in the non-tempered low emissivity coated glass that is manufactured with same process.

6.7.2 Test instruments

Abrasion testers shall comply with the specification of GB/T 5137.1.

6.7.3 Test procedure

6.8 Acid resistance

6.8.2 Test procedure

6.8.2.1 Before test, CLEAN two surfaces of the specimens with anhydrous ethanol.

6.9 Alkali resistance

After it is dried naturally, MEASURE the visible light transmittance of the specimen.

6.9.1 Sampling methods

The same with 6.8.1.

6.9.2 Test procedure

6.9.2.1 Before test, CLEAN two surfaces of the specimens with anhydrous ethanol.

After it is dried naturally, MEASURE the visible light transmittance of the specimens.

7.1 Inspection classification

7.1.1 Ex-factory inspection

Ex-factory inspection items are visible light transmittance in 5.2, 5.3, and 5.4; and 5.5.

7.1.2 Type inspection

Inspection items are all requirements specified in Chapter 5.

When one of the following conditions occurs, it shall conduct type inspection.

7.2 Group-batch and sampling

7.2.1 Group-batch

The products that have same process, same thickness, same nominal value of visible light transmittance, and stable continuous production can be consisted as a batch.

7.2.2 Sampling

7.2.2.1 During factory-exit inspection, the enterprise can draw up a reasonable sampling plan according to production condition to select specimens.

7.2.2.3 The specimen that is required for other test items can be randomly selected from this batch of products.

7.3 Determination rules

7.3.1 When measuring size deviation, thickness deviation, diagonal difference, curvature and appearance quality.

7.3.5 When testing abrasive resistance of product, only when all 3 specimens comply with the provisions of Table 5.6, then the indicators of this batch are qualified; otherwise it is unqualified.

7.3.6 When testing acid resistance of product, only when all 3 specimens comply with the provisions of Table 5.7, then the indicators of this batch are qualified; otherwise it is unqualified.

7.3.7 When testing alkali resistance of product, only when all 3 specimens comply with the provisions of Table 5.8, then the indicators of this batch are qualified; otherwise it is unqualified.

8.1 Packaging

8.2 Labeling

Packaging cases (pallets) shall have indications and labels such as manufacturer's name, trademarks, product names, thickness, categories, specifications, quantity, date of manufacture, instructions, coating surface indications, "handle with care", fragile, rain-proof, and stacking direction. […]

8.3 Storage and transportation