BS EN ISO 4611:2010 pdf download – Plastics — Determination of the effects of exposure to damp heat, water spray and salt mist (ISO 4611:2010)
4 General test conditions
4.1 Equipment requirements
4.1.1 General Equipment used for exposing specimens to steady state or cyclic exposure conditions involving heat, humidity, and water or salt spray shall be made from corrosion resistant materials that will not interact with or contaminate the specimens being exposed.
In addition, the device shall provide a means to programme and time the various portions of the exposure cycles that are used. Sensing devices for measurement of temperature and relative humidity shall be located within the working volume of the chamber. Any condensed water shall be continuously drained from the chamber and not re-used until re-purified. No condensed water from the walls or roof of the chamber can fall on the test specimens. Water used for the maintenance of the chamber humidity shall have a resistivity of at least 0,05 MΩ cm. For the water spray (see 4.2.2) and salt mist (see 4.2.3) tests, the following additional equipment requirements shall be met. The cabinet shall have a volume of not less than 0,4 m 3 since, with smaller volumes, difficulties have been experienced in ensuring an even distribution of spray. For large-volume cabinets, it is nevertheless necessary to ensure that the spray is distributed homogeneously throughout the cabinet. The upper parts of the inside of the cabinet shall be designed so that any drops of spray which form on its surface cannot fall on the specimens being tested. For the salt mist test (see 4.2.3), the apparatus should, for environmental reasons, preferably be fitted with equipment for treating the salt mist after the test, prior to releasing it to the atmosphere, and also with equipment for treating the salt water produced during the test, prior to discharging it to the sewage system. For the water spray (see 4.2.2) and salt mist (see 4.2.3) tests, the device for spraying the water or salt solution shall include a supply of compressed air, a reservoir containing the water or salt solution to be sprayed, and one or more atomizers.
Before it reaches the atomizers, the compressed air shall be passed through a filter to remove all traces of oil and solid matter, and the atomization shall be carried out at an overpressure of about 70 kPa. The level of the water or salt solution shall be maintained automatically. In order to prevent evaporation of water from the sprayed droplets, the compressed air shall be humidified, before entering the atomizer, by passing it through a saturation tower containing distilled or deionized water at a temperature 10 °C above that of the cabinet. For the salt mist test (see 4.2.3), the characteristics of the mist produced will depend on the pressure used and on the type of atomizer nozzle. These shall be adjusted so that the concentration of the salt mist in the cabinet (as measured by the rate of deposition of the mist on a collection surface) and the salt concentration in the mist are kept within the limits specified in 4.2.3. NOTE ISO 9142:2003, Annex E, describes exposure conditions similar to those used in this International Standard.
4.1.2 Temperature The exposure cabinet shall be capable of controlling the temperature in the exposure chamber to within ±2 °C of the desired equilibrium temperature. The temperature tolerance limits of ±2 °C are intended to allow for any systematic measurement errors, any temperature drift and any variations in temperature at different points in the chamber. However, in order to maintain the relative humidity throughout the chamber within the required tolerances, it is necessary to keep the temperature difference between any two points in the chamber at any given time within narrower limits. Specimens being exposed in the chamber shall not be subjected to radiant heat from the chamber temperature-control devices. The chamber temperature shall be measured at least 100 mm from the walls.