ISO 9227:2017 pdf free.Corrosion tests in artificial atmospheres – Salt spray tests.
6 Apparatus
6.1 Component protection
All components in contact with the spray or the test solution shall be made of. or lined with, materials resistant to corrosion by the sprayed solution and which do not influence the corrosivity of the sprayed test solutions.
The supports for the test specimen shall be constructed such that different substrate types do not influence each other. It shall also be constructed so that the supports themselves do not influence the test specimens.
6.2 Spray cabinet
The cabinet shall be such that the conditions of homogeneity and distribution of the spray are met. Due to the limited capacity of cabinets smaller than 0,4 m3, the effect of the loading of the cabinet on the clistribut ion of the spray and temperature shall be carefully considered. The solution shall not be sprayed directly onto test specimens but rather spread throughout the cabinet so that it falls naturally down to them. The upper parts of the cabinet shall be designed so that drops of sprayed solution formed on its surface do not fall on the test specimens being tested.
The size and shape of the cabinet shall be such that the collection rate of solution in the cabinet is within the limits measured as specified in 10.3.
Preference shall be given to apparatus that has a means for properly dealing with fog after the test, prior to releasing it from the building for environmental conservation, and for drawing water prior to discharging it to the drainage system.
NOTE A schematic diagram of one possible design of spray cabinet is shown in Annex A (see Figure A..1 and Figure A.2).
6.3 Heater and temperature control
An appropriate system maintains the cabinet and its contents at the specified temperature (see 10.1). The temperature shall be measured at least 100 mm from walls and radiant heat sources.
6.4 Spraying device
The device for spraying the salt solution comprises a supply of clean air, of controlled pressure and humidity, a reservoir to contain the solution to be sprayed, and one or more atomizers.
The compressed air supplied to the atomizers shall be passed through a filter to remove all traces of oil or solid matter, and the atomizing pressure shall be at an overpressure of 70 kPa1) to 170 kPa. The pressure is typically 98 kPa ± 10 kPa but can vary depending on the type of cabinet and atomizer used.
in order to prevent the evaporation of water from the sprayed droplets (aerosol), the air shall be humidified before entering the atomizer by passing through a suitable humidifier. The humidified air shall be saturated such that the concentration of the fallout solution falls within the specifications of 5.J.. The humidified air shall also be heated such that when mixed with the salt solution, there is no significant disturbance of the temperature in the cabinet. The appropriate temperature depends on the pressure used and on the type of atomizer nozzle. Temperature, pressure or humidification, or a combination thereof, shall be adjusted so that the rate of collection of the spray in the cabinet and the concentration of the collected spray are kept within the specified limits (see 10.3). A commonly used humidifier is the saturation tower, where temperature and pressure arc controllable. Table 1 gives guiding values on temperature and pressure combinations for the saturation tower.
The atomizers shall be made of Inert material. Baffles may be used to prevent direct impact of the spray on the test specimens, and the use of adjustable baffles is helpful in obtaining uniform distribution of the spray within the cabinet. For this purpose, a dispersion tower equipped with an atomizer may also be helpful.
The salt solution supplied to the nozzle shall be kept stable to ensure a continuous and uniform fall out as described in 103. A stable level of spraying can be achieved by either controlling the level of salt solution in the reservoir or restricting the flow of salt solution to the nozzle such that a continuous spray is achieved.
Distilled or deionized water with a conductivity not higher than 20 pS/cm at 25 °C ± 2 °C shall be used for huml(lifjcation of spray air.
6.5 Collecting devices
At least two collecting devices shall be used to check the homogeneity of the spraying of the cabinet. Suitable funnels shall be made of chemically inert material, with the stems inserted into graduated cylinders or other similar containers and have a diameter of 100 mm, which corresponds to a collecting area of approximately 80 cm2. The collecting devices shall be placed in the zone of the cabinet where the test specimens are placed, one close to an inlet of spray and one remote from an inlet. They shall be placed so that only mist, and not liquid falling from specimens or from parts of the cabinet, is collected.ISO 9227 pdf download.