BS EN ISO 877-2:2010 pdf free.Plastics – Methods of exposure to solar radiation Direct weathering and exposure behind window glass (ISO 877-2:2009).
BS EN ISO 877-2 The design of the specimen rack shall be suited to the types of specimen being exposed, but for many purposes a flat frame mounted on a support is suitable. The materials used to construct the frame shall conform to the requirements given in ISO 877-1:2009, Subclause 5.1. All materials used for the test fixture shall be corrosion-resistant without the need for surface treatment. Aluminum alloys 6061T6 and 6063T6 and stainless steel have been found suitable for use in most locations. Untreated wood may be acceptable for use in very dry locations. The test fixture may be adjustable with respect to both solar altitude (i.e. tilt) and azimuth.
The test fixture shall consist of an open-bottomed box with a framed cover of e.g. window glass, windscreen glass or automotive side-window glass. The box shall be ftted with a specimen rack that is positioned in a plane parallel to that of the glass cover and on which specimens may be mounted directly or in suitable holders. The materials used to construct the box and the rack to which the specimens are attached shall conform to the requirements of ISO 877-1:2009, Subclause 5.1. The test fixture may be adjustable with respect to both solar altitude (i.e. tilt) and azimuth. A schematic diagram of a set of acceptable under-glass exposure cases is shown in Figure 1.
Sufficient space between the cover and the rack is necessary to ensure adequate ventilation; a minimum of 75 mm has been found suitable. To minimize shadows, the usable exposure area under the glass shall be limited to the area of the glass cover reduced by the distance from the cover to the specimens.
The glass used for the cover shall be flat, uniformly transparent and without defects. For exposures under building-window glass, the glass cover shall be a piece of non-laminated, transparent flat glass. In order to reduce variability due to changes in UV transmission of glass, all new glass shall be pre-aged for a period of 3 months. The thickness of the glass shall be 2 mm to 3,2 mm. Refer to ASTM G 24 for guidance on glass pre-ageing, routine maintenance and the lifetime of such glass.
Other types of glass or glazing materials may be used as agreed upon by the interested parties.
NOTE 1 Exposure under glass may give rise to dfferent results compared to exposure to the open atmosphere because of a diference in spectral rradiance and a difference between under-glass and open-air temperature.
NOTE 2 Information about spectral transmission and solarization of window glass can be found in the fllowing paper: KETOLA, W.. ROBBINS, J.S., “UV Transmission of Single Strength Window Glass” in ASTM STP 1202, Accelerated and Outdoor Durability Testing of Organic Materials, Warren D. Ketola and Douglas Grossman (Eds). ASTM, 1993.
In order to ensure the greatest consistency in the exposure conditions, it is essential that the transmission of the glass used for method B exposures be regularly measured or that the glass be replaced on a regular basis.
If transmission measurements are used for this, monitor transmission at 320 nm. Replace the glass when the transmission at 320 nm has dropped to 80 % or less of the transmission measured when the glass was first installed. If transmission is not measured, replace the glass at least every five years.BS EN ISO 877-2 pdf download.