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IEC 60068-2-52 Environmental Testing – Part 2-52: Tests -Test Kb: Salt Mist, Cyclic (Sodium Chloride Solution)

In the realm of environmental testing, the IEC 60068-2-52 standard plays a crucial role. This standard specifically focuses on Test Kb, also known as Salt Mist, Cyclic (Sodium Chloride Solution). In this article, we will delve into the importance of this test, its applications, and how it aligns with industry standards, such as ASTM corrosion testing, including ASTM B117 Salt Spray Test. IEC 60068-2-52 is a comprehensive standard developed by the International Electrotechnical Commission (IEC) that outlines the testing procedures for salt mist or salt fog testing.

This testing method simulates the harsh conditions that products may be exposed to in marine or coastal environments, where the presence of saltwater mist can accelerate corrosion. IEC 60068-2-52 Test Kb – Salt Mist, Cyclic (Sodium Chloride Solution) is a vital component of environmental testing. It serves as a benchmark for salt fog testing, which allows manufacturers to evaluate corrosion resistance, surface coating durability, and material performance.

Complementing this, ASTM corrosion testing standards, such as ASTM B117 Salt Spray Test, offer further guidance and validation. By adhering to these industry standards and utilizing specialized salt mist test chambers, manufacturers can ensure the reliability and quality of their products in the face of corrosive environments. By subjecting products to accelerated corrosion conditions, manufacturers can identify vulnerabilities, improve their product designs, and select appropriate materials and coatings to enhance durability and longevity.

IEC 60068-2-52 Environmental Testing
Type and Description WEW-YW-120D WEW-YW-130D WEW-YW-160D
Inner Dimension(mm) 1200*800*500 1300*850*600 1600*1000*600
Outer Dimension(mm) 1700*1150*1200 1800*1200*1300 2300*1250*1450
Test Room Size (Liters) 500 Liters 650 Liters 1000 Liters
Power Supply AC 220V, 50Hz AC 220V, 50Hz AC 380V, 50Hz
Power Current 1Phase, 2.9 kW 1Phase, 3.5 kW 3Phase, 5.0 kW
Lid Opening Method Manual Opening Pneumatic Air-Operated
Brine Tank Volume 30 Literes 35 Literes 40 Literes
Test Room Temp Range Ambient Temperature +5℃ – +30℃, Ventilation is recommended, if the temperature exceeds +30℃, it is recommended to adjust the room temperature by suitable means. Ambient humidity should be controlled below 80%RH.
Test Room Temp Range RT+10℃ – +55℃ RT+10℃ – +55℃ RT+10℃ – +55℃
Saturated Barrel  RT+10℃ – +70℃ (Purpose: Heating and filtering of compressed air to reduce nozzle crystallisation.)
Temp Performance Temperature Uniformity: ≤2℃,  Temperature Fluctuation: ≤ ±0.5°C Temperature Uniformity: ≤2℃, 
Salt Mist Settling Rate 1~2 ml/80 cm2/h (Take 16 Hours To Test The Average Value) 1~2 ml/80 cm2/h
Spray Method Continuous, Intermittent,  Programmable Tests Continuous, Intermittent, 
Testing Type NSS, AASS,CASS NSS, CASS NSS, AASS,CASS
Safety Devices Over-Temperature Alarm (Mechanical Over-Temperature Protection + Electronic Over-Temperature Protection Double Over-Temperature Protection)
Air Requirements Inlet Pressure Above 0.4Mp. Two-Stage Pressure Regulation. Spray Pressure 0.07~0.17mp (Adjustable)
Sample Holder Special Samples Support Customisation. Special Samples Support Customisation. Load Capacity According To Actual Situation
Standard Configuration 1 Set Of V-Type/O-Type Shelves, 2 Bottles Of Test Drug Sodium Chloride (500g/Bottle), 1 Plastic Anti-Rust Bucket (5l Capacity), 1 Nozzle
salt spray testing

One of the primary applications of IEC 60068-2-52 is salt fog testing, also commonly known as salt spray testing. This test exposes products or materials to a controlled environment that generates a saline mist via a solution of sodium chloride. By subjecting the samples to this environment, it becomes possible to evaluate their resistance to corrosion, the durability of surface coatings, and overall material integrity. To perform tests according to IEC 60068-2-52 and other related standards, a salt mist test chamber is often utilized.

This specialized equipment allows for precise control of temperature, humidity, and the creation of a salt-laden mist. These chambers provide a controlled and repeatable environment to ensure accurate and reliable test results. In addition to the IEC standard, ASTM International has also defined its own corrosion testing methodologies, with ASTM B117 Salt Spray Test being a prominent one. ASTM B117 is widely recognized and used as a benchmark for salt spray testing across various industries. Its purpose is akin to IEC 60068-2-52, assessing the performance of materials and coatings when exposed to a salt-laden environment.

4.1 Description of each test condition 4 General Description of the Test
4.1.1 General
This document consists of the cyclic test conditions of salt mist, dry condition, humid condition and standard atmosphere. The effect of each test condition is as follows.
NOTE Salt mist is also called salt spray.
The test specimen(s) is typically not energized during the test.
4.1.2 Salt mist
The test specimen is corroded by an electrochemical or complex chemical reaction with neutral or acidified salt solution. Salt solution forms a thin electrolytic film on the test specimen surface. This can initiate corrosion and can allow it to proceed.
4.1 .3 Dry condition
Heated air in the chamber may cause evaporation of water from the test specimen surface from decreasing relative humidity and increased specimen temperature. This causes the concentration of the solution to increase and speeds up chemical reactions, accelerating the corrosion process. Salt precipitates out of the solution onto the test specimen surface during this condition. Evaporation and heating rates may vary based on the test chamber and test specimen.
4.1.4 Humid condition
4.1.4.1 Dry condition to humid condition
As the relative humidity increases, precipitated salt crystals on the specimen surface absorb water vapour until a liquid electrolytic solution forms, reinitializing the corrosion process.
4.1 .4.2 Salt mist to humid condition
The humid condition maintains the existing wetness on the test specimen surface at the end of the salt mist period, without excessive dilution of the solution that may result from condensing humidity.
4.1.5 Standard atmosphere
The test specimen is allowed to equilibrate with standard laboratory conditions, which results in gradual drying and relaxation from most corrosion reactions. The period of dry atmosphere may occur, in practice, during breaks of operation, for example during the weekend. 
The inclusion of such a dry period may lead to corrosion mechanisms which can be quite different from those under constant wet conditions. The test schedule shall be chosen in order to respect the timelines given in 9.4. Additional dry periods (e.g. during a weekend) shall be avoided.
The test specimen(s) shall be visually inspected and, if necessary, electrically and mechanically checked as required by the relevant specification. 7 Initial Measurements
The relevant specification shall specify the cleaning procedure to be applied immediately before the test; it shall also state whether temporary protective coatings shall be removed.  8 Preconditioning
The cleaning method used should not interfere with the effect of the salt mist on the test specimen(s), nor introduce any secondary corrosion. Touching of the test surfaces by hand should be avoided as far as possible before the test.
salt spray fog apparatus
Each test method includes two or more environmental conditions, which may be achieved by the use of multiple chambers or a single chamber that automatically transitions from one condition to the next. In either case, transitions are not assumed to be instantaneous. Care shall be taken to minimize any adverse effects associated with handling of specimens during transfer between chambers. 5.1 General 5 Test Apparatus
The chamber shall conform to the requirements of ISO 9227. It shall maintain a temperature of 35 °C ± 2 K.  5.2 Salt Mist Chamber
NOTE A schematic diagram of one possible design of spray cabinet is shown in Annex A
The chamber shall conform to the requirements of IEC 60068-2-78. It shall maintain a relative humidity of 93 % ± 3 % at a temperature of 40 °C ± 2 K or a relative humidity of over 95 % at a temperature of 50 °C ± 2 K. 5.3 Humidity Chamber
The chamber shall conform to the requirements of IEC 60068-1 . It shall maintain a relative humidity of 50 % ± 5 % at a temperature of 23 °C ± 2 K. 5.4 Standard Atmosphere Chamber
The chamber shall maintain a relative humidity of less than 30 % at a temperature of 60 °C ± 2 K. 5.5 Dry Chamber
The solution shall conform to the requirements of ISO 9227. 6.1 Preparation Of The Sodium Chloride Solution 6 Salt Solution
NOTE The sodium chloride concentration of the sprayed solution collected is 50 g/l ± 5 g/l. 6.2 pH adjustment 6.3 Filtration
6.2.1 Neutral salt solution
The pH adjustment shall conform to the requirements of ISO 9227 for the neutral salt solution test.
6.2.2 Acidified salt solution
Add the following reagents to 1 0 litres of the prepared neutral 5 % sodium chloride solution as follows: 1 2 ml of nitric acid (HNO 3 , ρ = 1 ,42 g/ml), 1 7,3 ml of sulfuric acid (H 2 SO 4 , ρ = 1 ,84 g/ml) and sufficient quantity of 1 0 % mass fraction of sodium hydroxide (NaOH) solution to adjust the pH of the solution to 3,5 ± 0,1 (about 300 ml will be required). The pH of the sprayed solution collected within the chamber is 3,4 to 3,6 at 25 °C ± 2 K.
If necessary, filter the solution before placing it in the reservoir of the apparatus to remove any solid matter which might block the apertures of the spraying device.
For test methods 1 and 2, a salt mist chamber and humidity chamber are used. 9.1 Test Chamber 9 Testing Methods
For test methods 3 to 6, a salt mist chamber, humidity chamber and standard atmosphere chamber are used. 
For test methods 7 and 8, a salt mist chamber, dry chamber and humidity chamber are used. All test methods may be performed in a single chamber provided it is capable of maintaining the required conditions. If not, care should be taken to avoid loss of salt solution deposits on the test specimen(s) and to avoid any damage to the test specimen(s) due to manual handling. 
For test methods 7 and 8, each condition should be carried out in the same chamber due to the difficulty in achieving the rapid drying and re-wetting intended if specimens are manually moved from one chamber to another.
It is recommended to use a specific chamber for testing test method 8 exclusively. Cross effects of remaining acidified salt solution when consequently using test method 1 to 7 cannot be ignored.
The arrangement shall conform to the requirements of ISO 9227. 9.2 Arrangement Of The Test Specimen(S)
The test conditions shall conform to the requirements of ISO 9227. 9.3 Conditions During Salt Mist
9.4.1 General 9.4 Test Methods
The relevant specification shall indicate which of the eight following test methods shall be used. A description of each test method is given in Annex B. When not specified, the test method shall be agreed by the interested parties.
The user should be aware of mass loss for each test condition.
9.4.2 Test method 1
One cycle is seven days. One cycle shall consist of spraying the specimen with a salt solution at 35 °C ± 2 K for 2 h, followed by the humid condition at 40 °C ± 2 K, 93 % ± 3 % RH for six days and 22 h. The required number of cycles is four (28 days).
In the case of manual handling, the transition time (maximum 2 h) should be included in the humid condition period of six days and 22 h.
9.4.3 Test method 2
One cycle is one day. One cycle shall consist of spraying the specimen with a salt solution at 35 °C ± 2 K for 2 h, followed by the humid condition at 40 °C ± 2 K, 93 % ± 3 % RH for 22 h.
The required number of cycles is three (three days).
In the case of manual handling, the transition time (maximum 2 h) should be included in the humid condition period of 22 h.
9.4.4 Test method 3
One cycle is seven days. One cycle shall consist of spraying the specimen with a salt solution at 35 °C ± 2 .K for 2 h, followed by the humid condition at 40 °C ± 2 K, 93 % ± 3 % RH for 22 h. This shall be repeated four times. The test specimens shall then be stored under standard atmosphere at 23 °C ± 2 K and 50 % ± 5 % RH for three days. The required number of cycle is one (seven days).
In the case of manual handling, the transition time (maximum 2 h) should be included in the humid condition period of 22 h and standard atmosphere period of three days.
9.4.5 Test method 4
The required number of cycles as specified in test method 3 shall be two (1 4 days).
9.4.6 Test method 5
The required number of cycles as specified in test method 3 shall be four (28 days).
9.4.7 Test method 6
The required number of cycles as specified in test method 3 shall be eight (56 days).
9.4.8 Test method 7
One cycle is 8 h. One cycle shall consist of spraying the specimen with a salt solution at 35 °C ± 2 K for 2 h, followed by the dry condition at 60 °C ± 2 K, under 30 % RH for 4 h and then the humid condition at 50 °C ± 2 K, over 95 % RH for 2 h.
The transition times (time allowed to reach the temperature and relative humidity specified for a condition after changing to that condition) for temperature and humidity shall be specified between the following choices and reported:
– salt mist to dry condition: within 30 min or between 30 min and 60 min;
– dry condition to humid condition: within 1 5 min or between 1 5 min and 30 min;
– humid condition to salt mist: within 30 min.
Those transition times shall be included in the next condition period of the pair, for example the salt mist to dry condition transition time is included in the period of the dry condition.
Spraying the specimen with a salt solution begins instantaneously once the salt mist is started.
The recommended number of cycles are 3 (1 day), 6 (2 days), 1 2 (4 days), 30 (1 0 days), 45 (1 5 days), 60 (20 days), 90 (30 days), 1 50 (50 days) and 1 80 (60 days).
9.4.9 Test method 8
One cycle is 8 h, as specified in test method 7 using acidified salt solution instead of neutral salt solution.
The recommended number of cycles is the same as in test method 7.
The test cycles for test methods 1 to 8 shall be in accordance with Table 1 . 9.5 Test Cycles For Test Methods 1 To 8
Table 1 - Test cycles for test methods 1 to 8
The test is recommended to be carried out in the same chamber (see Figure A.1 ). If not, care should be taken to avoid loss of salt solution deposits on the test specimen(s) and to avoid any damage to the test specimen(s) due to handling. 9.6 Removal Of The Test Specimen(S)
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