Operating SaltSpray(Fog)Apparatus1 StandardPracticefor
jo mea ap sa3pu uogueap aqp fumoog ppouu aquu aq Iig uoeuzsap poxg aq apun pang s ppueis sLoriginal adoption oc in the case of revisin the year of last revision. A number in parentheses indicates the year of last reapproval. A suescript pln () indicates an editrial chne since the last revisin or reappl.
This sfandondl lhasr bem approved for asr h) ngencier ef the U.S. Depermer of Defene.
D1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive EnvironmentsE70 Test Method for pH of Aqueous Solutions With the Glass ElectrodeE691 Practice for Conducting an Interlaboratory Study toG85 Practice for Modified Salt Spray (Fog) Testing Determine the Precision of a Test Method
1. Scope
1.1 This practice covers the apparatus procedure andconditions required to create and maintain the salt spray (fog)test environment. Suitable apparatus which may be used is described in Appendix X1.
1.2 This practice does not prescribe the type of test speci-men or exposure periods to be used for a specific product nor the interpretation to be given to the results.
3. Significance and Use
standard. The values given in parentheses are for information 1.3 The values stated in SI units are to be regarded as theonly.
3.1 This practice provides a controlled corrosive environ-ment which has been utilized to produce relative corrosion resistance information for specimens of metals and coatedmetals exposed in a given test chamber.
safety concerns if anry associated with its use. lt is the 1.4 This stondard does not purporr to address all of theresponsibility of the user of this standard to establish appro- pricte safery health and evironmental practices and deter-mine the applicabiliry of regulatory linitations prior to use.
seldom been correlated with salt spray results when used as 3.2 Prediction of performance in natural environments hasstand alone data.
dance with internationally recognized principles on standard- 1.5 This intermational standard was developed in accor-Developeent of Intermational Standards Guides and Re- ization established in the Decision on Principles for themendarions issued by the World Trade Organization Techunical Barriers to Trade (TBT) Conumitee.
mance based on exposure to the test environment provided by 3.2.1 Correlation and extrapolation of corrosion perfor-this practice are not always predictable.
only in cases where appropriate corroborating long-term atmo- 3.2.2 Correlation and extrapolation should be consideredspheric exposures have been conducted.
is highly dependent on the type of specimens tested and the 3.3 The reproducibility of results in the salt spray exposureoperating variables. In any testing program suffcient repli- evaluation criteria selected as well as the control of theresults. Variability has been observed when similar specimens cates should be included to establish the variability of theare tested in different fog chambers even though the testingconditions are nominally similar and within the ranges speci- fied in this practice.
2. Referenced Documents
2.1 ASTM Standards-2
B368 Test Method for Copper-Accelerated Acetic Acid-SaltD609 Practice for Preparation of Cold-Rolled Steel Panels Spray (Fog) Testing (CASS Test)for Testing Paint. Vamish. Conversion Coatings and Related Coating ProduetsD1193 Specification for Reagent Water
4. Apparatus
4.1 The apparatus required for salt spray (fog) exposureconsists of a fog chamber a salt solution reservoi a supply of suitably conditioned pressed air one or more atomizingnozzles specimen supports provision for heating the chamber and necessary means of control. The size and detailed con- spuoo ppaod euoo are sneedde o o uonnsobtained meet the requirements of this practice.
4.2 Drops of solution which accumulate on the ceiling orcover of the chamber shall not be permitted to fall on thespecimens being exposed.
4.3 Drops of solution which fall from the specimens shallnot be returned to the solution reservoir for respraying.
affect the corrosiveness of the fog. 4.4 Material of construction shall be such that it will not
4.5 All water used for this practice shall conform to Type IVwater in Specification D1193 (except that for this practice limits for chlorides and sodium may be ignored). This does notapply to running tap water. All other water will be refered to as reagent grade.
Not: 1Water used with a conductivity ≤1.0 μS/cm (or resistivity ≥1.0MΩ-cm may cause damage to some equipment due to the reactive nature of the water. In addition it may cause issues with stabilizing pHmeasurements.
5. Test Specimens
5.1 The type and number of test specimens to be used aswell as the criteria for the evaluation of the test results shall bedefined in the specifications covering the material or product uq uon ple e q us o pasoxo purchaser and the seller.
6. Preparation of Test Specimens
method shall be optional depending on the nature of the surface 6.1 Specimens shall be suitably cleaned. The cleaningand the contaminants. Care shall be taken that specimens are not recontaminated after cleaning by excessive or carelesshandling.
6.2 Specimens for the evaluation of paints and other organicspecification(s) for the material(s) being exposed or as agreed upon between the purchaser and the supplier. Otherwise thetest specimens shall consist of steel meeting the requirementsof Practice D609 and shall be cleaned and prepared for coating in accordance with the applicable procedure of Practice D609.
6.3 Specimens coated with paints or nonmetallic coatingsshall not be cleaned or handled excessively prior to test.
6.4 Whenever it is desired to determine the development ofcorrosion from an abraded area in the paint or organic coating a scratch or scribed line shall be made through the coating with aq e upn soxo se os n ds testing. The conditions of making the scratch shall be as defined in Test Method D1654 unless otherwise agreed uponbetween the purchaser and the seller.
coated or duplex materials and areas containing identification 6.5 Unless otherwise specified the cut edges of plated marks or in contact with the racks or supports shall be protected with a suitable coating stable under the conditions ofthe practice.
pelated pitd r wis cat l ht th ut es shal Note 2Should it be desirable to cut test specimens from parts or fromprotected by couting them with paint wax tape or other effective media so that the development of a galvanic efct between such edges and theadjacent plated or otherwise coated metal surfaces is prevented.
8.Salt Solution
7. Position of Specimens During Exposure
7.1 The position of the specimens in the salt spray chamberduring the test shall be such that the following conditions are met:
supported or suspended between 15 and 30° from the vertical 7.1.1 Unless otherwise specified the specimens shall beand preferably parallel to the principal direction of flow of fogtested. through the chamber based upon the dominant surface being
metallic material or any material capable of acting as a wick. 7.1.2 The specimens shall not contact cach other or any
bered exposure to the fog. 7.1.3 Each specimen shall be placed to permit unencum-
7.1.4 Salt solution from one specimen shall not drip on anyother specimen.
Nore 3Suitable materials for the construction or coating of racks andupots ae glass bber plastic or suitbly ctd woBaremeal w pddns q qed eqs sud posn aq u bottom or the side. Slotted wooden strips are suitable for the support of flat Suo se pasn q Aru us poxmm o sooq sse og uosusdng soudmeans of secondary support at the bottom of the specimens. as the specified position of the specimens is obtained if necessary by
8.1 The salt solution shall be prepared by dissolving 5 ± 1parts by mass of sodium chloride in 95 parts of water dx 61 ugds u I d o outhat for this practice limits for chlorides and sodium may be ignored). Careful attention should be given to the chemicalnot more than 0.3 % by mass of total impurities. Halides content of the salt. The salt used shall be sodium chloride withconstitute less than 0.1 % by mass of the salt content. Copper (Bromide Fluoride and Iodide) other than Chloride shallcontent shall be less than 0.3 ppm by mass. Sodium chloridethat has had anti-caking agents added shall not be used because such agents may act as corrosion inhibitors. See Table 1 for alisting of these impurity restrictions. Upon agreement between the purchaser and the seller analysis may be required andlimits established for elements or pounds not specified inthe chemical position given above.
8.2 The pH of the salt solution shall be such that whenatomized at 35°C (95°F) the collected solution will be in the pH range from 6.5 to 7.2 (Note 4). Before the solution isatomized it shall be free of suspended solids (Note 5). The pHmeasurement shall be made at 23 ± 3°C (73 ± 5°F) using a suitable glass pH-sensing electrode reference electrode andpH meter system in accordance with Test Method E70. pH measurement shall be recorded once daily (except onrupted for exposing rearranging or removing test specimens weekends or holidays when the salt spray test is not inter-or to check and replenish the solution in the reservoir. Themaximum interval between pH measurements shall not exceedadjust the pH. reagent grade sodium hydroxide (NaOH) shall be used to
Nor 4Temperature affects the pH of a salt solution prepared fromsnpe Hd pue ameadu uoou e pxo oqm qm pmes m ment may be made by the following three methods:
(7) When the pH of a salt solution is adjusted at room temperature and
Sodum Chloride^.s.C
TABLE 1 Maximum Allowable Limits for Impurity Levels in
solution to the atomizer may be covered with a double layer of cheeseclothto prevent plugging of the nozzle.
NorE 6The pH can be adjusted by aditions of dilute ACS reagentgrade hydrochloric acid or sodium hydroxide solstions.
No 1A measurale limit fr anti-caking agents is nrbeing definedas a result of how salt is manufactured. During salt manufacturing it ismon practice to create salt slurry from the raw salt mined. A crystallization process then captures the pure salt from this slurry. Some naturally occuring anti-caking agents can be fomed in this process andare not removed from the resultant product. Avoid salt products where extra anti-caking agents are added. Additionally when doing an elementalstand-alone element or part of an anti-caking agent. It is not economically analysis of salt there can be trace elements present that are either apossible anti-caking agents for which there would have to be testing. feasible to know where such elements came from due to the long list ofwith no anti-caking agents addd willb actaleThe sat supl can Therefore a alt produt that mets the impurity halide and copper lmitsagents were not added to the prodact. peovide an analysis of the salt with a statement indicating that anti-caking
9. Air Supply
shall be free of grease oil and dirt before use by passing 9.1 The pressed air supply to the Air Saturator Towerthrough well-maintained filters (Note 7). This air should be maintained at a sufficient pressure at the base of the AirSaturator Tower to meet the suggested pressures of Table 2 atthe top of the Air Saturator Tower.
Nore 7The air supply may be freed from oil and dirt by passing itthrough a suitable oil/water extractor (that is mercially available) to stop any oil from reaching the Air Saturator Tower. Many oil/waterintervals should take these into account. auru auaaad sdoad opu uogedxa ue aaeq soenxa
Total Impurties Impurty Description Allowable Amount ≤ 0.3%Halides (Bromide Fluoride and lodide) excluding Chloride Copper 0.3 ppm 99.9%. If the salt used is of lower purity then test for halides.
than the original solution due to the loss of carbon dioxide at the higher atomized at 35°C (95°F) the pH of the collected solution will be highertemperature. When the pH of the salt solution is adjusted at room temperature it is therefore necessary to adjust it below 6.5 so the collcted7.2. Take abot a 50-m samle of the salt solutin as pared at om temperature boil gently for 30 s col and determine the pH. When the solution after atomizing at 35°C (95°F) will meet the pH limits of 6.5 topH 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 e withinthis range.
10. Conditions in the Salt Spray Chamber
10.1 Tenperanore-The exposure zone of the sat spraychamber shall be maintained at 35 ± 2°C (95 ± 3°F). Each set od oo o e ss spe ofor equilibrium conditions at a single location in the cabinet
(2) Heating the salt solution to boiling and cooling to 35°C (95F) andmaintaining it at 35°C (95°F) for appoximately 48 h before adjusting the pH produces a solution the pH of which does not materially change whenatomized at 35°C (95°F).
for the Top of the Air Saturator Tower for the Operation of a Test TABLE 2 Suggested Temperature and Pressure Guidelineat 35°C (95°F)
(3) 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 whichdoes not materially change when atomized at 35°C (95°F).
Air Pressure kPa 96 83 Tempersture °C 46 47 Air Pressure _psi 12 14 117 114110 124 48 49 16 18 119 121
No: 5The freshly pepared salt solton may be filtered or dcantdbefore it is placed in the reservoir or the end of the tube leading from the
which may not necessarily represent the uniformity of condi-tions throughout the cabinet. The temperature within theexposure zone of the closed cabinet shall be recorded (Note 9) at least once daily (except on Saturdays Sundays and holidaysrearanging or removing test specimens or to check and when the salt spray test is not interrupted for exposing.replenish the solution in the reservoir)
ous reconding device or by a thermometer which can be read from outside Nom: 9A suitable method to record the temperature is by a continu-the closed cabinet. The reconded temperature must be obtained with the salt spray chamber closed to avoid a false low reading because of wet-bulbeffect when the chamber is open.
10.2 Atomizarion and Quanriry of FogPlace at least twoclean fog collectors per atomizer tower within the exposure zone so that no drops of solution will be collected from the testspecimens or any other source. Position the collectors in theproximity of the test specimens one nearest to any nozzle and the other farthest from all nozzles. A typical arrangement is80 cm² (12.4 in.²) of horizontal collecting area there will be shown in Fig. 1. The fog shall be such that for eachaverage run of at least 16 h (Note 11). The sodium chloride collected from 1.0 to 2.0 mL of solution per hour based on anconcentration of the collected solution shall be 5 ± 1 mass %(Notes 11-13). The pH of the collected solution shall be 6.5 to 7.2. The pH measurement shall be made as described in 8.2condensate collected (measured in mL) shall be recorded once (Note 4). Both sodium chloride concentration and volume ofis not interrupted for exposing rearranging or removing test daily (except on weekends or holidays when the salt spray testspecimens or to check and replenish the solution in thereservoir. The maximum interval between these data collection measurements shall not exceed 96 h).
Nom: 10Common methods of measuring sodium chloride concentra-tion are specific gravity hydrometer salimeter hydrometer refractometer and titration. This list is not all inclusive of every method and an
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the stems inserted through stoppers into graduated cylinders or crystal Nore 11Suitable collecting devices are glass or plastic funnels withan area of about 80 cm² (12.4 in.2). lizing dishes. Funnels and dishes with a diameter of 10 cm (3.94 in.) have
smd Nor 12The specific gravity of salt solution will change withspecification. The sample to be measured may be a posite sample from ture? and can be used to determine if the sample measured is withinmultiple fog-collecting devices within a single cabinet if necessary to obtain sufficient solution volume for measurement.
6 % salt solution between 20°C and 40°C. A measurement that falls within Table 3 shows the salt concentration and salt density of 4 % 5 % andthe range between 4 % and 6 % is acceptable.
It is important to understand the equipment being used to measurethe use of a hydromter. If used carful atnti t th bydrmt specific gravity. One mon peactice for specific gravity measurement is is important as most are manufactured and calibrated for measurements atbe necessary to make an accurate measurement at other temperatures. 15.6°C (60°F). Since salt density is temperature dependent an offset willContact thehydrmeter mafacturer to find the poper ofset for the hydrometer being used.
though for uniformity the limits are set at 4 to 6 %. Nore 13Salt solutions from 2 to 6 % will give the same results
10.3 The nozzle or nozzles shall be so directed or baffledthat none of the spray can impinge directly on the test
11. Continuity of Exposure
ing the material or product being tested the test shall be 11.1 Unless otherwise specified in the specifications cover-continuous for the duration of the entire test period. Continu-ous operation implies that the chamber be closed and the spray operating continuously except for the short daily interruptions
applicable for multiple atomizer tower and horizontal *T" type) atoeizer tower cabinet constructions as well. os s o us qe mo ze aus e u o ed e ss mg 1 3FIG. 1 Arrangement of Fog Collectors
TABLE 3 Temperature versus Density Data
Temperature Density g/om?°C (°F) 4-percent Salt Concentration 5-percent Salt Concentration 6-peroent Sall Concentration21 (69.8) 20 (68) 1.025758 1.025480 1.032360 1.032067 1.038867 1. (71.6) 23 (73.4) 24 (75.2) 1.024596 1.025193 1.024899 1.031766 1.031142 1.031458 1.038245 1.037924 1. (78.8) 25 （77)） 1.024286 1.023969 1.030819 1.030489 1.037261 1. (80.6) 28 (82.4) 1.023643 1.023311 1.030152 1.029808 1.036570 1. (84.2) 30 (86) 31 (87.8) 1.022971 1.022624 1.022270 1.029457 1.029099 1.028735 1.035853 1.035485 1. (89.6) 33 (91.4) 1.021910 1.021542 1.027986 1.028364 1.034729 1. (93.2) 35 (95) 1.021168 1.020787 1.027602 1.027212 1.033950 1.(100.4) 37 (98.6) 36 (96.8) 1.020399 1.020006 1.019605 1.026005 1.026413 1.026816 1.033146 1.032735 1. (102.2) 40 (104) 1.019199 1.018786 1.025590 1.025170 1.031897 1.031469
necessary to inspect rearrange or remove test specimens to check and replenish the solution in the reservoir and to makenecessary recordings as described in Section 10.
Nom 14Operations should be so scheduled that the cumulative H oqsod p Aep 1ad uogdu uo juo aamq on ppuuoa s 1 maximum time for these interruptions are held to 60 min or less per day.interruption time is longer that 60 min it should be noted in the test report.
12. Period of Exposure
specifications covering the material or product being tested or 12.1 The period of exposure shall be as designated by theas mutually agreed upon between the purchaser and the seller.
between the purchaser and the seller but exposure periods of multiples of Nom: 15Remended exposure periods are to be as agred upon24 h are suggested.
13. Cleaning of Tested Specimens
ss ps so ss sing the material or product being tested specimens shall betreated as follows at the end of the test:
13.1.1 The specimens shall be carefully removed.
s ano o (0 1ou mu 13.2 Specimens may be gently washed or dipped in cleandeposits from their surface and then immediately dried.
14. Evaluation of Results
required by the specifications covering the material or product 14.1 A careful and immediate examination shall be made asbeing tested or by agreement between the purchaser and theseller.
15. Records and Reports
15.1 The following information shall be recorded unlessotherwise prescribed in the specifications covering the materialor product being tested:
15.1.1 Type of salt and water used in preparing the saltsolution.
of the chamber. 15.1.2 All readings of temperature within the exposure zone
volume of salt solution collected in millilitres per hour per 15.1.3 Data obtained from each fog-collecting device of80 cm² (12.4 in.2).
15.1.4 Concentration or specific gravity of collected solu-tion and the temperature of that solution when measured.temperature to determine that the sample measured is within Follow Table 3 for salt concentration and density versusspecification. Sample to be measured may be a posite sample from multiple fog-collecting devices (within a singlecabinet) if necessary to obtain sufficient solution volume formeasurement.
15.1.5 pH of collected solution at 23 ± 3C (73 ± 5°F).Sample to be measured may be a posite sample from multiple fog-collecting devices (within a single cabinet) ifnecessary to obtain sufficient solution volume for measure-ment.
15.2 Type of specimen and its dimensions or number ordescription of part
15.3 Method of cleaning specimens before and after testing.
15.4 Method of supporting or suspending article in the saltspray chamber
15.5 Description of protection used as required in 6.5
15.6 Exposure period
15.7 Interruptions in exposure cause and length of time and
15.8 Results of all inspections.
the test specimens is returned to the reservoir it is advisable to record the Nore 161f any of the atomized salt solution which has not contactedconcentration or specific gravity of this solution also.
