JPH0371063B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention is applicable to various electrical contacts, connection terminals, metals, painted metals, and parts and products made from these materials that are free from corrosive gases. Regarding corrosion test equipment.

b. Problems to be solved by conventional technology and the invention Gas corrosion tests that have been performed in the past have been conducted by subjecting metal corrosive highly concentrated gases such as sulfur dioxide, nitrogen oxide, hydrogen sulfide, carbon dioxide, and ammonia to air, nitrogen, etc. This is done in an atmosphere where the metal is mixed and diluted with a non-corrosive gas to maintain a constant concentration. It is known that there is a close relationship between the gas concentration and the corrosion rate of corrosive gases, especially at low concentrations.

Although the gas concentration greatly influences the test results, conventional gas corrosion test equipment only uses various techniques to keep the gas concentration fed into the test tank constant, and the gas concentration in the tank It was insufficient in responding to fluctuations in In addition, in the conventional technology that detects fluctuations in the gas concentration in the tank and can adjust the amount of gas to be fed, the gas feeding mechanism is an intermittent type, takes several minutes to respond, and may not work at certain times of the day. The operation was repeated intermittently, with high-concentration gas being pumped in and then completely stopped during the following period. Therefore, even though the gas concentration in the tank is approximately at the predetermined concentration on average, the range of concentration fluctuation is quite large and is within ±5.
The current situation is that around 20% is considered unavoidable. This is the main reason for questioning the reproducibility of gas corrosion test results.

Further, the corrosive dilute gas used in the gas corrosion tester is sent to the test tank as a synthetic gas for testing, which is a mixture of high concentration gas diluted with air, nitrogen, etc. at a certain ratio. For example, the specific gravity of sulfur dioxide is
Although it is difficult to homogeneously mix gases with such a large difference in specific gravity or gases with poor compatibility, conventional test equipment does not carefully consider this mixing. Not yet. For this reason, the concentration of the corrosive gas sent to the test chamber is unstable, which is one of the causes of insufficient reproducibility of test results.

c. Means and Effects for Solving the Problems As explained above, the present invention always maintains the corrosive gas concentration in the test tank constant, which is the biggest factor in worsening the reproducibility of gas corrosion test results. We provide highly reliable test equipment.

Below, before describing the configuration of the present invention, the meanings of terms will be defined.

Corrosive gases: Chemically active gases mainly for metal materials, such as sulfur dioxide, nitrogen oxide, hydrogen sulfide, carbon dioxide, ammonia, and chlorine.

Reference gas: High purity and high concentration standard gas with known concentration of corrosive gas. Raw material gas used to create diluted gas by diluting with air, etc.

Dilution gas: A non-corrosive gas that is diluted with the reference gas. air, nitrogen, etc.

Dilution gas: The reference gas was uniformly mixed and diluted with a dilution gas.

The present invention is constituted by the following three requirements. (1)
Most of the required standard gas volume (approximately 90% or more) is always fed in a constant amount continuously, and the remainder (approximately 10% or less)
It is sent in a state that can be adjusted according to the concentration in the test tank. (2)
In order to maintain the gas concentration in the tank constant, a detection adjustment triangular bridge as shown in FIG. 1 is formed. This triangular bridge first detects the concentration in the tank with a detection cell,
This is sent as a quantitative electrical signal to the adjustment control section, and the control section compares and calculates the electrical quantity corresponding to the set concentration with this signal electrical quantity. If there is a difference, this is immediately sent as an electrical signal to the flow rate regulator, and the regulator automatically adjusts the valve so that a reference gas equal to the amount of the electrical signal flows. In this way, as soon as the concentration in the tank begins to fluctuate, the detection and adjustment triangular bridge is activated to constantly adjust the concentration in the tank so that it does not fluctuate.
(3) Since it is difficult to uniformly mix sulfur dioxide, which has a high specific gravity, or gases that are poorly compatible with the dilution gas, a specially constructed mixer is installed in front of the test chamber to increase mixing efficiency. Provided for.

d Example An embodiment of the present invention will be explained with reference to FIG.

In the figure, the test tank 20 adopts a generally known structure for corrosion testing machines, etc., and has a cubic shape, for example, so that the temperature and humidity inside the tank can be controlled, and the gas introduced into the tank can be prevented from leaking. It has a sealed structure to prevent it from happening. The corrosive gas is sent into the tank through the exhaust pipe of the secondary mixer (described later). Further, the exhaust gas treatment device is placed close to the test tank 20, and performs chemical treatment depending on the gas, for example, in order to release the corrosive gas discharged from the tank into the atmosphere as a safe gas. It is something.

A gas cylinder 1 is filled with a corrosive gas, such as sulfur dioxide, and is connected to a pressure reducing valve 2 and a precision pressure reducing valve 3 in order to accurately reduce the pressure to a predetermined pressure. In addition, in order to flow most of the corrosive gas at a constant rate, the decompressed corrosive gas is divided into a route A, in which a flow rate control valve 4, a solenoid valve 5, and a quantitative flowmeter 6 are arranged in order, and the remainder that flows through the route A. A flow rate control valve 8 and a control flow meter 9 are arranged in this order to allow the flow of the water to flow in a controlled manner. Both lines are connected to a primary mixer 10 (described later).

The air compressor 11 supplies a certain amount of air to dilute the above gas to a predetermined concentration, and various devices (described later) are arranged in the system that feeds the gas to the primary mixer 10. be.

In addition, a gas concentration detection section 21 having a detection cell is provided in the test chamber 20 and is arranged outside the test chamber 20, and the amount of current generated by the gas concentration detection section 21 is compared with the amount of current stored in advance. An adjustment control section 22 that sends the difference to the flow rate adjustment section 7 is provided. The flow rate adjustment section 7 is connected to the flow rate adjustment valve 8 of the B line.

Next, the operation of this device will be explained.

An example will be explained in which the gas concentration in the test chamber is maintained at 10 ppm by using a standard gas (concentration guaranteed) of sulfur dioxide (10000 ppm) in a cylinder as the reference gas and compressed air from an air compressor as the dilution gas. Air 99.9/min and reference gas 0.1
Calculatedly, 10 ppm of sulfur dioxide can be obtained by mixing the standard gas at 0.1/min to the following two routes.

A system: constant flow rate of 0.1/min x 0.9 = 0.09/min B system: adjustable flow rate of 0.1/min x 0.1 = 0.01/min A system constantly supplies an amount equivalent to approximately 90% of the reference gas This is a system for sending gas at a constant flow rate, and the gas leaving the gas cylinder 1 passes through a pressure reducing valve 2 and a precision pressure reducing valve 3, and the pressure is reduced to 0.15.
Precisely adjust the flow rate to Kg/cm ³ , and adjust the flow rate control valve 4 so that the reading on the quantitative flowmeter 6 is 0.09/min.

The B line is a line that automatically adjusts and sends an amount equivalent to about 10% of the reference gas, and under normal conditions
Since a flow rate of 0.01/min is required, the flow rate adjustment valve 8 must be set to the control flow meter 9 so that the flow can flow to about 2 to 3 times this value, that is, 0.02 to 0.03/min, and the flow rate should be 0.01/min when properly adjusted. /min flow rate. The solenoid valves 5 and 16 open when the device is turned on and close when the device is stopped.

The reference gas for both the A and B lines is connected to the primary mixer 10.
to go into. On the other hand, the air for dilution is air compressor 1.
1, the pressure is further adjusted by the pressure reducing valve 15 through the pressure reducing valve 12, the oil/water separator 13, and the activated carbon filter 14.
The gas flows through the electromagnetic valve 16, is accurately adjusted to 99.9/min by the flow control valve 17 and the flow meter 18, enters the primary mixer 10, and is mixed with the reference gas. Although not shown in detail, the primary mixer is a sealed cylindrical container, in which a pipe connecting to the A and B systems is inserted into one end, and a diluent gas system and a secondary mixer are inserted into the other end. (described later) A tube is inserted that connects to the This mixed gas enters a secondary mixer 19 for further uniform mixing. FIG. 3 shows an example of the structure of the secondary mixer 19. In the figure, the secondary mixer has a cylindrical shape with both end faces closed, and a narrow central pipe a is inserted into the center of one end face for feeding the mixed gas from the primary mixer into the cylinder. Furthermore, an exhaust pipe communicating with the test chamber 20 is fixed to this end face. The end of the central pipe a is located near the other end surface of the cylinder, and T-shaped branch pipes b and b', which have discharge ports facing in opposite directions toward the inner circumferential wall of the cylinder, are attached at right angles to this end. be. The first funnel-shaped partition umbrella c is inserted into the center tube a with a uniform gap, with its tip end facing the penetration end surface of the center tube a;
The periphery of the cylinder is fixed in close contact with the inner wall at the center of the cylinder. The second funnel-shaped bulkhead d has a substantially similar shape to the first funnel-shaped bulkhead c, and is inserted into the center tube a symmetrically with the first funnel-shaped bulkhead c. The protruding end portion is fixed in close contact with the center tube a so that the peripheral edge portion has a uniform distance from the cylindrical inner wall circumference at an approximately intermediate position with the penetrating end surface. Therefore, it has the function of forcibly and uniformly mixing sulfur dioxide with a high specific gravity ratio and air. The mixed gas from the primary mixer reaches the bottom of the mixer through a thin tubular center pipe a that penetrates the center of the cylindrical secondary mixer with both ends closed, and here it reaches the bottom of the mixer at right angles to the center pipe a. T-shaped branch pipes b and b' are provided in mutually opposite directions, and the tips of each branch pipe are parallel to the mixer wall and the flow is in mutually opposite directions. After the gases exiting from b and b' collide with the inner wall of the mixer at their respective angles, they turn into a vortex as they flow toward the outlet while rotating around the central pipe a.
It is compressed at the tip of the first funnel-shaped bulkhead c, then rapidly expands and diffuses, and repeats the compression and expansion at the second funnel-shaped bulkhead d. By repeating this vortexing, compression, expansion and diffusion, sulfur dioxide and air are mixed completely and uniformly. The mixed gas then enters the test chamber 20 approximately.
Continuously fed at 100/min at a concentration of 10 ppm. In the test tank, the test sample is placed at the specified temperature and humidity, and as the sulfur dioxide is consumed and the concentration in the tank decreases locally, a stirring fan is installed to stir the gas concentration in the tank to make it uniform. keep.

Furthermore, the test chamber is provided with a detection cell in the gas concentration detection section 21, and in this embodiment is equipped with an electrolyzer that converts a change in composition due to a chemical reaction of a reaction liquid that reacts with sulfur dioxide into an amount of electrochemically generated electric current.
In the case of sulfur dioxide, a cell known as a commonly used chromometry method can be used as the detection cell. The current generated in this cell is exactly proportional to the sulfur dioxide concentration in the bath. The current generated by the detection cell is controlled by the adjustment control section (including an automatic concentration adjustment recorder) 2.
2, where the amount of current generated when the gas concentration in the test chamber is exactly 10 ppm is stored.
The value is compared with the amount of current sent from the detection unit 21, and the difference becomes an electric signal again to the flow rate adjustment unit 7.
The flow rate control valve 8 is adjusted according to the signal amount. That is, as soon as the detection cell 21 detects the gas concentration in the tank, the reference gas flow rate in the B line is adjusted by an electric signal.

In the device of the present invention, in this way, approximately 90% of the reference gas supply amount is constantly sent through the A line, and even if the gas concentration in the test chamber slightly fluctuates, the remaining approximately 10% remains. The control valve in the B line that sends the amount of gas operates to adjust the amount of incoming gas, so the concentration inside the test tank is always maintained at a constant concentration.

In addition, as a method for detecting the gas concentration in the test chamber, it is possible to use the above-mentioned detection cell's infrared absorption method, ultraviolet absorption method, solution conductivity method, flame photometric detection method, etc. In this case, the gas flow rate can also be adjusted by sending a response electric signal proportional to the gas concentration to the flow rate adjustment section 7.

e Effects of the Invention In the device of the present invention, the gas concentration fed into the test tank is accurately adjusted to a predetermined concentration and a uniformly mixed gas is fed, so fluctuations in the gas concentration inside the test tank are reduced. , the variation in corrosion test results is small, and test results that accurately correspond to the test gas concentration can be obtained.

In the conventional technology, even if the average value of the gas concentration in the test tank is a predetermined concentration, the gas concentration in the test tank may fluctuate because the gas with adjusted concentration is fed intermittently and in a non-uniformly mixed state. Because of this large amount, the test results varied greatly, making it unclear to judge the results. There are even cases in which the results of the Japanese Industrial Standard H8502 ``Plating Corrosion Resistance Test Method'' vary within the range of 2 to 4 regarding the ``Rating Number Table by Total Corrosion Area Ratio'' of the test sample. In addition, for example, the gas concentration often used in normal corrosion tests using sulfur dioxide gas, nitrogen oxide gas, etc.
It is considered that the concentration error around 25 ppm is unavoidable at about ±5 to 20%.

However, recent research has revealed that the degree of corrosion of metals caused by these gases is particularly highly dependent on the gas concentration in the vicinity of 5 to 20 ppm. Corrosion tests centered around 10ppm are becoming more important. Therefore, maintaining the gas concentration in the test chamber as accurately as possible is an essential condition for improving the performance of test machines in the future.

When using the apparatus of the present invention, the variation in the gas concentration in the test chamber is ±0.2 ppm at a set concentration of 5 ppm, and the range of variation in the rating number is 1 to 1.5 if other conditions are kept constant.

[Brief explanation of drawings]

Figure 1 shows the detection adjustment triangular bridge of the present invention, the second
The figure is an explanatory diagram of the gas concentration adjustment mechanism of the present invention, and FIG. 3 is an explanatory diagram of the structure of the secondary mixer according to the present invention. 1...Gas cylinder, 6...Quantitative flow meter, 7...
Flow rate adjustment unit, 8...Flow rate control valve, 9...Adjustment flow meter, 10...Primary mixer, 19...Secondary mixer,
20...Test tank, 21...Gas concentration detection section, 22
...adjustment control unit, 23...exhaust gas treatment device.

Claims (1)

[Claims] 1. In a device that accelerates the corrosion of a sample by sending a corrosive gas into the test tank, the system A, through which most of the highly concentrated corrosive gas flows at a constant flow rate, and a portion of the highly concentrated corrosive gas are connected to the test tank. Gas consists of a B system line which has a flow rate adjustment section for adjusting the flow rate according to the internal gas concentration, and a dilution gas line line that allows air to flow at a constant flow rate to dilute the highly concentrated corrosive gas to a predetermined concentration. The difference between the mixing system, the gas concentration detection section installed in the test chamber, and the amount of electricity from the gas concentration detection section that corresponds to fluctuations in the gas concentration in the test chamber and the amount of electricity that corresponds to the preset gas concentration in the test chamber. an adjustment control unit that sends a signal to the flow rate adjustment unit, a primary mixer in which each system of the gas mixing system communicates and naturally mixes each gas, and an intermediate mixer between the primary mixer and the test tank, It consists of a secondary mixer that forcibly mixes the gas from the primary mixer and sends it into the test chamber, and the secondary mixer is further comprised of a cylinder with both end faces closed, and a cylinder that penetrates from one end face of the cylinder. T-shaped branch pipes b and b' have outlet ports in opposite directions toward the inner circumferential wall of the cylinder on the other end surface thereof, and are thin tube-shaped tubes for feeding the mixed gas from the primary mixer into the cylinder. A central tube a is disposed in the center of the cylinder with a protruding end facing the penetrating end surface of the central tube a, a peripheral edge is fixed to the inner wall of the cylinder, and the central tube a is connected to the protruding end with a gap. A first funnel-shaped bulkhead umbrella c to be inserted, having a shape substantially similar to the first bulkhead umbrella c, and fixing the tip end to the central tube a so that the peripheral edge has a gap with the cylindrical inner wall circumference; and a second funnel-shaped bulkhead umbrella d disposed symmetrically with the first bulkhead umbrella c, and an exhaust pipe connected to the test chamber provided on one end surface of a cylinder penetrating the central tube a; A gas corrosion test device that controls the gas concentration in the test chamber and also supplies a uniformly mixed gas into the test chamber.