Principle and installation of salt spray corrosion test box

Corrosive solution is sprayed into mist by compressed air, which surrounds the sample in the test chamber.

Testing can be continuous or cyclic.

The corrosion resistance of each sample is defined as the time when the sample is corroded. The longer the time, the better the corrosion resistance.

The technical data of the salt spray corrosion test chamber is 1. Please connect the power supply of salt fog box and air compressor first, and connect the air compressor pipe.

2. Add pure water or distilled water to the water inlet inside and behind the box until the low water level lamp on the panel goes out, otherwise it will not work normally.

3. The connection between the drain pipe and the exhaust pipe is completed. As shown on the previous page, the indicator remains on.

4. Add water to the isolation tank to the gasket position to avoid salt spray leakage.

5. Preparation method of test solution:

A. covering layer, neutral salt spray test (NSS test)

A. The salt solution is made of sodium chloride (chemically pure and analytically pure) and distilled water or deionized water, and its concentration is (5% 0. 1)% (mass percentage). The liquid collected after atomization shall not be reused except the part blocked by the baffle;

B the PH value of the salt solution before atomization is between 6.5 and 7.2 (35 2℃). When preparing salt solution, the PH value can be adjusted by chemically pure dilute hydrochloric acid or sodium hydroxide solution, but the concentration should still meet the requirements of point A. ..

B. metal coating, copper accelerated acetate spray test (CASS test)

A, dissolving sodium chloride in distilled water or deionized water with the concentration of 50+/-5g/L.

B. add copper chloride (CuCl2 2H2O) to solution a, and its concentration is 0.26 0.02g/l (i.e. 0.205 0.015g/l/l anhydrous copper chloride).

C, adding a proper amount of glacial acetic acid into solution A, so that the pH value of the salt mist collection liquid in the test box is 3. 1 ~ 3.3. If the pH value of the solution before spraying is 3.0 ~ 3. 1, the pH value of the collected solution is generally in the range of 3. 1 ~ 3.3. The pH value of the solution can be measured by an acid meter, or after proofreading by an acid meter, a precise pH test paper with a pH change of 0. 1 can be read for daily detection. The pH value of the solution can be adjusted by glacial acetic acid or sodium hydroxide.

To avoid nozzle clogging, the solution must be filtered before use.

6. Pour the saline into the saline solution replenishment bottle, that is, automatically inject the saline into the spray tower of the laboratory, so that the drugs can flow to the saline spray tower.

7. Add water to the wet bulb, cover the wet bulb thermometer on the gauze, and put the end of the gauze in the wet bulb.

8. Put the test piece or sample on the shelf: the arrangement angle should be set according to the required standard. For example, the standard specimen 130×70(mm) may be inclined 15 degrees and 30 degrees.

9. Set the test temperature: set according to the required standard (press "▲" to increase, press "▼" to decrease).

A.NSS and AASS tests: the laboratory temperature is 35℃; The temperature of the saturated air barrel is 37℃ (35℃ ~ 40℃).

B.CASS test: the laboratory temperature is 50℃; The temperature of the saturated air barrel is 55℃ (50℃ ~ 55℃).

10. Set the test time: 0 ~ 999 hr (h: h: press "+"to add; The key "-"is to decrease)

1 1. Press the power supply, operate the key, preheat first, and reach the set temperature. Note: Cover the test cover and handle it carefully to avoid damage.

Press the spray button:

A, open the air outlet valve in front of the air compressor, and adjust the pressure to the primary pressure of 0.2 ~ 0.4 MPa;

B, adjust the pressure regulating valve to the pressure of 0.07 ~ 0. 17 MPa, and its pressure can be known by the pressure gauge (increasing clockwise and decreasing counterclockwise).

13. Press the timer button to time according to the set time.

14. After the test, turn off the switches in sequence.

15. If there is any abnormality in the test, please refer to the function abnormality judgment table. When the salt spray test box is used for product testing, it usually works for one month or even several months, and the harsh environment is easy to cause large and small failures of the salt spray tester. In order to enable users to quickly deal with the faults of the salt spray test box and continue the salt spray aging test smoothly, some common faults and treatment methods are introduced in detail.

A, salt spray test box spray fault causes and treatment:

Insufficient low spraying quantity:

1, the spray regulator is set too low, and the spray regulator is raised.

2. If the glass filter in the preheating box is blocked, please clean the glass filter.

3. Check whether the nozzle is partially blocked. If it is blocked, please discharge the sundries.

4, the pressure setting is too low, adjust the pressure regulating valve.

● Unable to spray:

1. The air compressor is not running. Turn on the air compressor button and check whether the air pipe of the air compressor is connected correctly.

2. Check whether the pressure of the pressure regulating valve is open. Please adjust to the normal pressure value.

3. Check whether the nozzle is blocked. Nozzle is a consumable. Generally, it is damaged normally after being used for more than 1500 hours. The nozzle should be replaced.

4. Check whether the spray switch is damaged. If damaged, please replace the switch.

5. Check whether the spray solenoid valve is damaged. If there is an air inlet but no air outlet, remove the solenoid valve and clean it. If the coil is burnt, the coil matching the solenoid valve needs to be replaced, otherwise the entire solenoid valve will be replaced.

6. Check whether there is reagent brine. If there is no brine, add an appropriate amount of reagent brine.

Second, the salt spray test box heating failure causes and treatment:

● The salt spray test box cannot be heated:

1. The heating solid state relay has no output. Replace the solid state relay.

2. If the instrument has no output, replace the instrument.

3. If the heating pipe is damaged, check the resistance of the heating pipe, and replace it if it is abnormal.

4, lack of water leads to heating shielding, check whether the water level is normal and whether the floating ball is correct.

5. If the overtemperature protection malfunctions, adjust the protection temperature value. If it still cannot be solved, please replace the overtemperature protection.

● Abnormal heating temperature of salt spray test box:

1. The temperature setting of the laboratory temperature controller is too low. Set the temperature controller at the required temperature.

2. The safety protection switch in the laboratory is set too low. Please set the safety protection switch at the required temperature.

3. If the temperature of the temperature controller of the saturated barrel is too low, set the temperature controller at the required temperature.

4. The safety protection switch of the saturated barrel is set too low, so set the safety protection switch at the required temperature.

Three, salt spray test box instrument no display:

1. Is there a power supply for the salt spray test box? If there is no power supply, please have it checked by a professional electrician.

2. Is the power switch damaged? If so, please replace the power switch.

3. Is the power circuit breaker damaged? If so, please replace the circuit breaker.

4. Whether the power supply terminal of the instrument has power supply, if so, the instrument is damaged and needs to be replaced.

5. Check the wiring terminals of instrument power supply of salt fog box for signs of blackening. If it turns black, it means that the instrument may be burned and should be replaced.

Sample placement

The salt spray test box uses a certain concentration of salt solution or acidic salt solution to carry out accelerated salt spray corrosion test at a certain temperature and relative humidity. The salt spray test box is mainly used to evaluate the salt spray corrosion resistance of sample materials and their coatings, electroplating layers and other protective layers, and to compare the process quality between similar and identical protective layers.

The working temperature of the salt spray test box is between room temperature and 55℃ and can be kept constant. Under the condition of constant relative humidity and temperature, carry out salt spray corrosion test on materials or products in a salt spray test box with specified working room volume (generally 150L, 270L, 1000L, etc.). ). Then, how to put the test sample in the salt spray test box when testing? The scientific resettlement method is:

1. Place the sample in the salt spray test box with the test surface facing upward, so that the salt spray generated during spraying in the salt spray test box can freely settle and deposit on the test surface of the sample, instead of being directly sprayed on the test surface of the sample.

2, the test sample should generally level off. In the salt spray test box, the test surface of the sample should be15 ~ 30 from the vertical, and 20 as far as possible, and the irregular sample (such as the whole workpiece) should be as close as possible to the above requirements.

3. The test samples can be placed on different levels of Wuhan salt spray test box, but they must not touch the test box or touch each other. The distance between the test samples shall not affect the free fall of salt spray on the test surface, and the salt spray droplets gathered on the test samples shall not drop on other test samples. For a new salt spray test with a total test time of more than 96 hours, the sample can be moved.

4. The sample rack is made of glass, plastic and other materials that are resistant to salt fog and acid and alkali corrosion. If it is necessary to hang the sample on the bracket, the material for hanging the sample should not be metal, and nonmetallic materials, such as cotton fiber, man-made fiber or other insulating materials, are generally used.

The general test support number is 8- 10, and the V-shaped sample support number is 8- 10. Of course, it can be increased or decreased according to the quantity, size and test cycle of the customer's test samples, and it should be stated when ordering.

The above method solves the problem of how to place the test samples in the salt spray test box, please refer to it. 1. The back of the salt spray test box is about 50cm away from the wall. Leave proper maintenance space on the left and right sides.

Second, before the main power cord of the machine, please install a fuse-free switch or a knife switch.

Third, the fog exhaust pipe can be extended to the outside along the PVC rigid pipe with a diameter of 50. Pay attention to the installation of the mist exhaust pipe, which should be inclined downward from the height of the nozzle.

Four, the installation position of salt spray test box, please avoid direct sunlight, so as not to affect the test conditions.

Five, the box is made of PVC plastic to prevent collision, and the use temperature cannot exceed the test standard range to avoid overheating and deformation.

6. Overtemperature indicator: When the overtemperature indicator is on, the overtemperature of the laboratory is protected. Please check whether the temperature setting of the temperature instrument is too high or whether the temperature control setting is too low.

Seven. Low water level indicator lamp: When the low water level indicator lamp is on, the laboratory or saturator is short of water protection and the working power supply will be cut off. At this point, check whether the laboratory or saturator leaks water.

8. End indicator: When this indicator is on, it means that the test is over.

9. Salt spray test box power supply: 380 V/220 V 50 Hz;

Adjustment of air pressure

Answer: The inlet pressure is manually adjusted by the first-stage pressure regulating valve, which is generally controlled at 2~4kg/cm2.

B: Adjust the spray pressure from the pressure reducing valve to 0.5~ 1.7kg/cm2. Upstream adjustment has been adjusted before leaving the factory, and users generally do not need to adjust.

Preparation scheme

Preparation of neutral salt spray solution

Dissolve analytically pure sodium chloride in pure water with the concentration of (50 10) g/L, and measure the PH value of the test solution at 25℃ with a PH test paper. When it exceeds the range, it can be adjusted by adding analytically pure hydrochloric acid or sodium hydroxide solution.

Preparation of acetate mist solution

Firstly, analytically pure sodium chloride was dissolved in pure water with the concentration of (50 10) g/L, and then the PH value of the solution was adjusted to 3. 1 ~ 3.3 with acetic acid, and the salt spray samples were collected for determination. The PH value should be determined at 25℃, and the prepared solution should be filtered before use.

Copper accelerated solution preparation

The first step is to put analytically pure sodium chloride solution into water conforming to GB6682XX, and the concentration is (5010) g/L. ..

Step 2: Add reagent grade copper chloride into 3.8 liters of salt water to dissolve and mix thoroughly.

(3) using acetic acid to adjust the PH value of the solution within the range of 3. 1 ~ 3.2, using