Procedure for preparing saline solution for corrosion testing in accordance with ASTM B117 and ISO 9227.

Method of preparation:

1) Weigh the sodium chloride on the balance (1,500 grams), then transfer it to a container for preparing the solution.

2) Add 48.5 liters DEI water, in accordance with ASTM D1193 – Type IV, in the solution preparation container and stir the solution until the sodium chloride is completely dissolved.

• It is possible to measure the concentration of the sodium chloride content through a gravity hydrometer equipment, which must meet the concentration of 5%, see table below.

NOTE: Adjustment of the density of the obtained solution is outside the limits required by the standard, the

   solution must be corrected by adding more salt or more water to obtain the desired value.

       3) Add prepared solution in a beaker and check the pH value of 6.5 to 7.2. (ASTM B117 and ISO 9227)

      4) The solution sprayed in the chamber is collected, and pH and density analyze are 

       performed to verify compliance with the chosen test standard. If the values obtained

       are outside the provisions of the standard, the prepared solution is corrected as

       described below.

Procedure for measuring pH in saline solution.:

When the pH of a salt solution is adjusted at room temperature and atomized at 35 °C (95 °F), the pH of the collected solution will be higher than the original solution due to the loss of carbon dioxide at the higher temperature.

When the pH of the salt solution is adjusted at room temperature, it is therefore necessary to adjust it below 6.5 so the collected solution after atomizing at 35 °C (95 °F) will meet the pH limits of 6.5 to 7.2.

Take about a 50 mL sample of the salt solution as prepared at room temperature, boil gently for 30 s, cool, and determine the pH. when the pH of the salt solution is adjusted to 6.5 to 7.2 by this procedure, the pH of the atomized and collected solution at 35 °C (95 °F) will come within this range.

Heating the salt solution to boiling and cooling to 35 °C (95 °F) and maintaining it at 35 °C (95 °F) for approximately 48 h before adjusting the pH produces a solution the pH of which does not materially change when atomized at 35 °C (95 °F).

Heating the water from which the salt solution is prepared to 35 °C (95 °F) or above, to expel carbon dioxide, and adjusting the pH of the salt solution within the limits of 6.5 to 7.2 produces a solution the pH of which does not materially change when atomized at 35 °C (95 °F).

NOTE —The freshly prepared salt solution may be filtered or decanted before it is placed in the reservoir, or the end of the tube leading from the solution to the atomizer may be covered with a double layer of cheesecloth to prevent plugging of the nozzle.

NOTE —The pH can be adjusted by additions of dilute ACS reagent grade hydrochloric acid or sodium hydroxide solutions.