How to distinguish ordinary glass from low

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How to distinguish ordinary glass from low

Low-E glass is increasingly favored by the construction market because of its superior energy-saving performance. Due to the increase of sales volume and the maturing of manufacturing level, the price of Low-E glass has also decreased, and the scope of application has rapidly expanded from the initial high-end public buildings to ordinary civil buildings

how to distinguish ordinary glass from Low-E glass

in practical application, if it is already known that it is Low-E glass, it is relatively simple to distinguish the position of Low-E film surface. However, due to the particularity of Low-E glass, it is difficult for ordinary people to distinguish it from ordinary coated glass or even non coated glass only in appearance

1. The most accurate way to identify Low-E glass by photometer measurement is to use far 1. When the pointer of the spring fatigue tester moves abnormally, the transfer switch should be turned to the loading gear: infrared spectrophotometer measures the emissivity of the glass surface. According to gb/t18915. According to the standard of low radiation coated glass, the offline Low-E glass emissivity is ≤ 0. 15. Low-E glass emissivity ≤ 0. 25。 This is also the method used by authoritative glass inspection institutions

however, since only small pieces of single glass can be detected, the insulating glass must be disassembled into single glass before it can be carried out. At the same time, because the far-infrared spectrophotometer is expensive, this method is not suitable for rapid determination of processing and use site

2. It is necessary to be accurate when applicable to the power supply voltage; The cable connecting the sensor and the host shall not have an intermediate joint. In the field judgment method, the single Low-E glass is the best one. At present, the application of single-chip Low-E in the domestic market is mainly Yaohua Low-E glass, which can be further processed like ordinary glass, such as tempering, hot bending, sandwich and so on. This kind of glass can measure and judge the emissivity of the glass surface with a portable surface emissivity meter, but the more simple and practical method is the surface resistance measurement method

3. Conductivity measurement method because the thermal reflection of Low-E glass is actually the result of the action of free electrons and electromagnetic waves in the film, the surface of Low-E glass is conductive

the surface resistance value of ordinary non coated glass is infinite. The surface resistance value of sunlight controlled coated glass will decrease according to the different coating materials, but it is still very high. The square resistance value of Low-E glass surface is generally below 20 ohms

with this feature, we can quickly identify. The square resistance value of the glass surface should be measured with a four probe tester. The square resistance can be measured by placing the measuring head on the dry and clean glass surface. The square resistance can be converted into emissivity through the relevant formula, so as to determine whether it is Low-E glass

it can also be judged simply by using an ordinary multimeter. Place the pen tip of the multimeter on the glass surface, and the distance between the positive and negative pen tips is about 1 cm. At this time, if the displayed resistance value is dozens of ohms, it can be judged to be a low-E glass film surface. If it is more than 100 ohms, it is not a low-E glass film surface. However, this method is easily affected by the pen tip spacing, contact pressure and contact area, so it should be comprehensively judged by measuring more points

4. Because the Low-E membrane surface is placed in the insulating glass when synthesizing insulating glass, it is difficult to determine whether Low-E is used in insulating glass

although the heat transfer coefficient of Low-E insulating glass is much lower than that of ordinary insulating glass, it is not easy to quickly measure the heat transfer coefficient of glass on site. At present, the relatively simple method is to use the conductivity principle of Low-E glass without damaging the insulating glass

also points out the direction for the development of plastic granulator technology in China.

a weak electromagnetic field is produced by using electromagnetic coils or capacitors. When Low-E glass coated with conductive film approaches this electromagnetic field, it will change the state of the electromagnetic field, thereby affecting the output current or output voltage

based on this principle, we can detect whether there is a low-E membrane inside the insulating glass, and we can know whether the Low-E membrane is far or near according to the size of the change. At present, the Low-E membrane surface tester with relatively mature technology on the market is based on this principle. Place the handheld Low-E tester close to the surface of the insulating glass, press the test button, and judge whether there is a low-E membrane surface according to the flashing state of the indicator light

this method is fast and simple, without disassembling the insulating glass, so it has good promotion value. However, if the area of insulating glass is too small, the test results are easily affected by the edge aluminum strip or window frame, and the test results are not authoritative, that is, when the instrument determines that there is a low-E film, it cannot be guaranteed that it must be a low-E product that meets the standard

5. Image measurement method at present, there is a popular identification method: put matches or bright objects in front of the window glass, and observe the four images (in other words, there are four flames or four images) in the glass. If it is Low-E glass, the color of one image is different from the other three images. If the color of the four images is the same, it can be determined that Low-E glass is not installed

this method is based on the principle that even colorless high permeability Low-E glass will have a slight reflection color. It is only applicable to the simple discrimination between white glass insulating glass and colorless Low-E insulating glass

6. There are other simple identification methods for hollow Low-E glass. Although each has its own limitations, it is conducive to comprehensive use. When offline Low-E synthetic hollow, the edge film needs to be removed, so it can be determined by checking whether there is a dividing line between glass and membrane near the glass edge and the spacer strip

low-e synthetic hollow does not remove the edge film, so it can also be judged by resistance method where the edge sealant does not cover the inner surface of the glass

to sum up, the identification method of single Low-E glass is relatively simple, and it is difficult to accurately determine hollow Low-E without disassembly. At present, many researchers are studying more practical detection instruments

in practical engineering applications, we can make a comprehensive judgment through the above methods, but the most accurate way is to recommend the method of randomly taking samples from actual products and sending them to authoritative testing departments for testing, which can not only identify whether it is Low-E glass, but also test its performance

global glass () Department

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