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Environmental Test Chambers for SAE J2020 Accelerated Aging Test

Environmental Test Chambers for SAE J2020 Accelerated Aging Test Apparatus
 
Lenpure UV Lamp Weathering Test Chambers adopt fluorescent UV lamp as light source to simulate the UV irradiation in natural light and condensation to conduct accelerated weathering test to the materials. It can simulate the UV, rain, high temperature, high humidity, condensate, darkness and other environmental conditions in natural climate and combine them in a circle, and carry out these circles automatically.
 
 
 
This test method specifies the operating conditions for a fluorescent ultraviolet (UV) and condensation apparatus used for the accelerated exposure of various automotive exterior components. Specimen preparation, test duration, and performance evaluation procedures are addressed by each automotive manufacturer's material specifications.
 
This SAE Standard may involve hazardous materials, operations, and equipment. This document does not purport to address all of the safety problems associated with its use. This test method is designed to simulate extreme environmental conditions encountered on the outside of an automobile due to sunlight, heat, and to provide an acceleration of exposure for the purpose of predicting the performance of exterior automotive materials.
 
This test method is designed to simulate extreme environmental conditions encountered on the outside of an automobile due to sunlight, heat, and to provide an acceleration of exposure for the purpose of predicting the performance of exterior automotive materials.
 
3.1 BLACK PANEL THERMOMETER
 
A temperature measuring device consisting of a metal panel, having a black coating which absorbs all wavelength uniformly with a thermal sensitive element firmly attached to the center of the exposed surface. The black panel thermometer is used to control an artificial weathering device and to provide an estimate of the maximum temperature of specimens exposed to a radiant energy source.
 
3.2 IRRADIANCE
The radiant power per unit area incident on a receiver, typically reported in watts per square meter, W/m2.
 
3.3 IRRADIANCE, SPECTRAL
The distribution of irradiance as a function of wavelength (W/m2/nm).
 
3.4 SPECTRAL POWER DISTRIBUTION (SPD)
The absolute or relative radiant power emitted by a source, or incident upon a receiver as a function of wavelength.
 
3.5 FLUORESCENT UV LAMP
A lamp in which the irradiance from a low pressure mercury arc is transformed to a higher wavelength UV by a phosphor.The spectral power distribution of a fluorescent lamp is determined by the emission spectrum of the phosphor and the UV transmittance of the glass tube.
 
3.6 APPARATUS
A more complete description of the apparatus may be found in ASTM G 154.
 
3.6.1 Test Chamber, constructed of corrosion-resistant materials enclosing eight fluorescent UV lamps. a heated water pan, test specimen racks. and provisions for controlling and indicating operating times and temperatures
 
3.7 Lamps shall be rapid start, medium bi-pin fluorescent UV type with a length of 1200 mm, and a nominal rating of 40w.
 
3.7.1 The lamps shall be one of the following types:a. UVB lamps with a peak emission of 313 nm as described in Table 3 of ASTM G 154. A representative spectral power distribution of this lamp is shown below.

 
 
NOTE: In devices that do not automatically control irradiance, "FS-40" or "F40UVB" type lamps have historically been used In devices that automatically control irradiance. UVB-313 lamps may be used.
 
3.7.2 Other fluorescent UV lamps meeting the size and electrical characteristics in 3.7 may be used by prior agreement, provided that the lamp and spectral power distribution are reported in conformance with the Report section. Use of lamps other than those specified in 3.7 may result in significant differences in test results.
 
UVA lamps with a peak emission of 340 nm as described in Table 1 of ASTM G 154. A representative spectral power distribution of this lamp is shown below.

 
 
3.8 LAMP SPACING AND ARRANGEMENT
The lamps shall be mounted in two banks of four lamps each. The lamps in each bank shall be mounted in a flat plane on 70 mm centers.
 
3.8.1 Lamp manufacturing techniques typically result in a slight gradient in light output from one end of a lamp to the other end. To compensate for this, see figure 3.
 
3.9 TEST SPECIMENS
The test specimens shall be mounted in stationary racks with the plane of the surface parallel to the plane of the lamps at a distance of 50 mm from the nearest surface of the lamps.
 
3.10 CONDENSATION MECHANISM
Water vapor shall be generated by heating a water pan extending under the entire specimen area and containing a minimum water depth of 20 mm. Specimen racks and the test specimens themselves shall constitute the side walls of the chamber.The back side of the specimens shall be exposed to cooling effects of ambient room air. The resulting heat transfer causes water to condensate on the test surface.
 
3.10.1 Water Supply
Supply water with an automatic control to regulate the level in the water pan shall be provided. Distilled. deionized. or potable tap water are equally acceptable for purposes of the test. since the condensation process itself distills water onto the test surface.
 
PROCEDURE
Mount the test specimens in the specimen racks with the test surfaces facing the lamp. When the test specimens do not completely fill the racks, the empty spaces must be filled with panels to maintain the test conditions within the chamber.
 
5.2The test specimens shall be exposed within an area 210 mm in height by 900 mm wide on each side of the apparatus located as shown in Figure 3.
NOTE: To avoid areas of variability in the specimen exposure area, do not use the extreme right- and left-hand specimen holders on the apparatus.
 
5.3Set Condensation Cooling Timer to 15 min, if applicable. Report any variations in the test report Figure 4.
5.4Initiate all exposures at the beginning of the condensation cycle.
 
5.5Program the Cycle Timer to achieve the following test conditions: 8 h UV light exposure at 70 C, alternating with 4 hours condensation exposure at 50 ℃..
 
5.5.1Operating continuously, repeating the cycle, except for servicing the instrument and inspection of specimens.Inspect specimens weekly durig the condensation cycle for evidence of condensation.
 
5.6In order to minimize any effect from temperature or UV light variation, specimens shall be repositioned periodically. As a minimum, specimens must be rotated horizontally once each week by (a) moving the two extreme right-hand specimen holders to the far left of the exposure area and (b) sliding the remaining specimen holders to the right.
 
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