ATLAS ultraviolet lamps UVA and UVB use introduction

 

I. UVA: Main Lamp Models UVA-340, UVA-351

　　Features: UVA lamps are particularly useful for comparing different types of polymer testing. Since UVA lamps do not have any output below the 295nm cutoff of normal sunlight, they generally degrade materials less rapidly than UVB lamps. However, they usually give a better correlation to actual outdoor aging.

　　UVA-340 provides a simulation of sunlight in the region from 365nm down to the sunlight cutoff of 295nm for critical shortwave. The peak emission is at 340 nm. UVA-340 lamps are particularly useful for comparative testing of different formulations.

　　UVA-351 mimics the UV portion of sunlight passing through window glass. This is effective for indoor applications, especially to replicate the loss of polymer that occurs in window environments. This lamp is more commonly used in appliance coatings and automotive interior coatings.

 

Second, UVB: the main lamp models UVB-313, QFS-40

　　Characteristics: UVB lamps are widely used for fast, economical testing of durable materials. There are currently two types of UVB lamps. They produce the same UV wavelengths, but the total energy produced is different. All UVB lamps emit short-wave UV, below the sunlight cutoff of 295 nm, and although this is accelerated short-wave UV testing, it can sometimes lead to abnormal results.

　　The UVB-313 is a widely used QUV lamp for UVB exposure. It is very useful in accelerated chemical testing of very durable products such as automotive coatings and roofing materials. UVB-313EL lamps are also often used in QC applications.

 

I. Quartz glass tube materials

　　Ultraviolet germicidal lamp (UV lamp) is actually a low-pressure mercury lamp belonging to the ultraviolet weather tester, and ordinary fluorescent lamps, the use of low-pressure mercury vapors (<10-2Pa) is excited by the emission of ultraviolet light. General germicidal lamp lamps are made of quartz glass, because the UV weatherproof test box quartz glass has a high transmittance rate of ultraviolet light bands, up to 80% -90%, is to do germicidal lamps zui good material. Although quartz is more expensive, but all used for UV polymerization reaction of mercury vapor lamps are made of quartz, the lamp head material more gum wood, plastic or ceramic.

 

Second, high borax glass tube material

　　Because of the cost relationship and different uses, there are also used in the ultraviolet penetration rate of <50% of the high borax glass tube instead of quartz glass. High-boron glass production process and energy-saving lamps, so the cost is very low, but it is in the ultraviolet weatherproof test chamber performance is far less than the quartz glass tube to do the ultraviolet germicidal lamps, the germicidal effect is quite a big difference. High boron lamps UV intensity is easy to attenuate, lighted hundreds of hours after the UV intensity fell dramatically to the initial 50% -70%. The quartz lamp in the ignition 2000-3000 hours, the ultraviolet intensity is only reduced to the initial ultraviolet weatherproof test box 80% -70%, the degree of light decay is much smaller than the high boron lamp.

 

Third, ordinary glass materials

　　This transmittance of ultraviolet light is higher than the UV weatherproof test chamber using ordinary glass, much higher than high boron glass, slightly lower than quartz glass, light failure is still greater than quartz germicidal lamps, and can not produce ozone.

　　Note: quartz has three important properties are well suited to the production of UV lamps:

　　1, low coefficient of thermal expansion, the purity of quartz and the presence of other trace compounds can affect the emission characteristics of the lamp.

　　2, Transparent to UV, absorbs no or very little UV.

　　3, is a poor conductor of heat, the lamp is a fused quartz tube, the wall thickness of about 1MM, the outer diameter of 20~25MM, the total length of the arc lamp up to 2M, the complex layout of the electrodes (electronic emitters, pedestals, conductors, etc.) sealed in the UV weatherproof test box quartz tube at both ends of the quartz tube, the quartz tube contains mercury used to emit energy as well as the start-up gas, usually argon gas. When the luminaire is energized, an arc is generated between the two poles of the UV weather tester. As the voltage between the electrodes increases, the temperature of the gas rises, causing the mercury to evaporate, generating a mercury vapor arc and emitting characteristic ultraviolet light. When operating at full power, the luminaire also emits visible light as well as some infrared (IR) light.