JPS6162840A - Gas corrosion testing apparatus performing adjustment of flow amount by two-route gas feeding - Google Patents

Abstract

PURPOSE:To always keep the concn. of the corrosive gas in a testing tank constant, by controlling a flow regulation part by the difference between the signal value from a gas concn. detection part and the signal value to the concn. of the predetermined gas in the testing tank. CONSTITUTION:In a testing tank, a detection cell is provided to a gas concn. detection part 21. The current generated in this cell is accurately proportional to the concn. of SO2 in the tank. The current generated in the detection cell is sent to an adjustment controll part 22, where the concn. of the gas in the testing tank is accurately stored, and the value of said concn. is compared with the quantity of the current sent from the detection part 21 and the difference therebetween is sent to a flow regulation part 7 and a flow regulation valve 8 is regulated corresponding to the signal quantity thereof. As a result, about 90% of the supply amount of reference gas is steadily sent in a constant amount by an A-route and, even if the concn. in the tank varies minutely, the regulation valve of a B-route is operated to keep the concn. in the tank always constant.

Description

[Detailed Description of the Invention] a. Field of Industrial Use The present invention is applicable to various electrical contacts, connection terminals, metals, painted metals,
Or, it relates to a corrosion test device using corrosive gas for parts and various products made by these talented people 1.

b. Problems to be solved by the conventional technology and the invention The conventional gas corrosion test uses sulfur dioxide, nitrogen oxide,
The process is carried out in an atmosphere where highly concentrated gases that corrode metals, such as hydrogen sulfide, carbon dioxide, and ammonia, are mixed and diluted with gases that do not corrode metals, such as air and nitrogen, to a constant concentration. It is generally known that there is a close relationship between gas concentration and corrosion rate of corrosive gases, especially at low concentrations.

this. Despite the fact that gas concentration greatly affects 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 cannot be controlled. It was insufficient in responding to fluctuations. In addition, with conventional technology that detects fluctuations in the gas concentration in the tank and can adjust the amount of gas fed, the gas feeding mechanism is intermittent and takes several minutes to respond, and during periods when the gas concentration is high. The operation was repeated intermittently, with gas being pumped in and then completely stopped for the next period of time. Therefore, even if the gas concentration in the tank is approximately a predetermined concentration on average, the concentration fluctuation range is quite large and is considered to be unavoidable within the range of ±5 to 20%. This is the main reason for questioning the reproducibility of gas corrosion test results.

In addition, the corrosive diluted 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, air, nitrogen, etc. at a constant ratio and dilution. For example, the specific gravity of sulfur dioxide is 226 times that of dry air, and although it is difficult to uniformly mix gases with such a large difference in specific gravity or gases with poor compatibility, No careful consideration was given to this mixing in the test equipment of A1. Therefore, the concentration of the corrosive gas sent to the test tank is unstable, which is one of the reasons why the Furukawa characteristics of the test results are insufficient.

Means and Effects for Solving Problem C The present invention, as explained above, 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 structure of the present invention, the term ``child'' will be defined.

Corrosive gases, chemically active gases such as carbon dioxide, nitrogen oxide, hydrogen sulfide, carbon dioxide, ammonia, and chlorine, mainly for metals.

Reference gas: High purity or 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: A gas obtained by uniformly mixing and diluting the reference gas with a diluent gas.

The present invention is constituted by the following three requirements.

(1) Most of the required amount of reference gas (approximately 90% or more) is always sent in a constant constant amount, and the remainder (approximately 10% or less) is sent in an adjustable state depending on 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, sends this as a quantitative electric signal to the adjustment control section, and the control section compares and calculates the amount of electricity corresponding to the set concentration with this signal amount of electricity. 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 starts to fluctuate, the detection and adjustment triangular burr is activated, and the concentration in the tank is always adjusted so as not to fluctuate. (3) Since it is difficult to uniformly mix gases such as sulfur dioxide with high specific gravity or gases with poor compatibility with the dilution gas, a specially constructed mixer to increase mixing efficiency is installed in front of the test chamber. Provided for.

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

Sulfur dioxide 5 (] 0.OOOppm as reference gas
An example will be explained in which the gas concentration in the test chamber is maintained at 10 ppm by using a standard gas (with guaranteed concentration) in a cylinder as the dilution gas and compressed air from a near compressor as the dilution gas. Air 99.9 l/min and reference gas 0.1
10 ppm of sulfur dioxide is calculated by mixing 0.1 l/m of this reference gas.
In is divided and supplied to the following two routes.

A route: 0.1 l/min x 0.9 = 0.
091) /min constant flow rate B line: 0.1 l/min x 0.1 = 0.
The A line with an adjustable flow rate of 0.01 l/min is a thread line that constantly sends an amount equivalent to about 90% of the reference gas at a constant flow rate. Precisely adjust the pressure to 9/Cn1 to 0.15 through the pressure reducing valve 3, and use the flow rate adjustment valve 4 to ensure that the reading on the quantitative flow meter 6 is 0.
．． Adjust to 09 l/min.

The B line is a thread path that automatically adjusts and sends an amount equivalent to about 10% of the reference gas, and under normal conditions, the amount is 0.01 l/
min is required, so the setting for the control flow meter 9 by the flow control valve 8 should be approximately 2 to 3 times this value, that is, 0.0
The structure should be such that it can flow up to 2 to 0.03 l/min, and the flow rate should be O, O] l/min when properly adjusted.

The solenoid valves 5 and 16 open when the device is turned on and close when the device is stopped.

The reference gases from both the A and B paths enter the primary mixer 10.

On the other hand, dilution air is supplied from the air compressor 11 to the pressure reducing valve 12.
, an oil/water separator 13, an activated carbon filter 14, the pressure is further adjusted by a pressure reducing valve 15, and a solenoid valve 16 is passed through a flow rate regulating valve 1.
7 and flow meter 18 exactly 99.9 l/min
The gas flows into the primary mixer 10 and is mixed with the reference gas. 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, which has a function of forcibly and uniformly mixing sulfur dioxide and air with a large difference in specific gravity. The bottom of the mixer is reached via a tube a penetrating the center of the closed cylindrical secondary mixer, where T-shaped branches are formed at right angles to the tube a and in mutually opposite directions.

b' so that the ends of each branch and tube are parallel to the mixer wall and flow in opposite directions. b, b
After colliding with the inner wall of the mixer at different angles, the gas coming out of 'A' becomes a vortex while rotating around the central pipe a and flowing towards the outlet, is compressed at the tip of the partition umbrella C, and then rapidly expands and diffuses. Then, the compression and expansion are repeated again using the umbrella d. Through this repetition of swirling, compression, and expansion/diffusion, sulfur dioxide and air are mixed completely and uniformly. The mixed gas is then fed into the test chamber 20 at approximately 100 l/min.

Continuously fed at a concentration of 10 ppm. In the test tank, the test sample is placed at the specified temperature and humidity, and since the sulfur dioxide is consumed and the concentration in the tank decreases locally, a stirring device is installed to stir the gas concentration in the tank to make it uniform. keep.

Furthermore, a detection cell is provided in the gas concentration detection section 21 in the test chamber,
In this embodiment, an electrolytic device is provided which converts a change in composition due to a chemical reaction of a reaction liquid reacting 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 sent to the adjustment control unit (including an automatic concentration adjustment recorder) 22, where the current generated when the gas concentration in the test chamber was exactly 10 ppm is stored, and the value is recorded. and the amount of current sent from the detection unit 21,
The difference is again in the air.

The signal is sent to the flow rate adjustment section 7, where the flow rate adjustment 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 path is adjusted by an electric signal.

In the apparatus of the present invention, 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% is supplied. Since the control valve of the B line is operated to adjust the amount of gas flowing in, the concentration inside the test tank is always maintained at a constant concentration.

In addition to the above-mentioned detection cell, infrared absorption method, ultraviolet absorption method, solution conductivity method, flame photometric detection method, etc. can be used as a method for detecting the gas concentration in the test chamber. 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 apparatus of the present invention, since fluctuations in the gas concentration in the test tank are small, variations in corrosion test results are 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 concentration fluctuations are large, so that the test results have a large error rate, making it unclear to judge the results. In the judgment of the results according to the Japanese Industrial Standard H8502 "Corrosion resistance test method for plating", there are even cases where the test sample's "ratein number according to total corrosion area ratio" varies in the range of about 2 to 4 with respect to Table 1. In ordinary corrosion tests using gases, nitrogen oxide gas, etc., it is considered that an error in concentration of about ±5 to 20% is unavoidable at a gas concentration of around 25 ppm, which is often used.

However, according to recent research, the degree of corrosion of metals caused by these gases is
It has recently become clear that the dependence on gas concentration is large. 10
Corrosion tests centered around ppm 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 future testing machines.

In the case of the device of the present invention, the fluctuation in the gas concentration in the test chamber is ±0.2 ppm at a set concentration of 5 ppm, and if other conditions are kept constant, the rating number fluctuation range is 1 to 1.
It is 15.

[Brief explanation of the drawing]

Fig. 1 is a detection adjustment triangular bridge of the present invention, Fig. 2 is an explanatory diagram of the gas concentration adjustment mechanism of the present invention, and Fig. 3 is a bridge according to the present invention.
It is a structural explanatory diagram of a secondary mixer.

Claims (2)

[Claims] (1) Consisting of a system A through which most of the highly concentrated corrosive gas flows in a constant amount, a system B through which a portion of the gas flows at a variable rate according to the gas concentration in the test chamber, and a dilution gas system path. A gas mixing system to be used, a gas concentration detection section installed in the test chamber, an electric signal value emitted from the gas concentration detection section in response to fluctuations in the gas concentration in the test chamber, and a signal corresponding to a predetermined gas concentration in the test chamber. A gas corrosion test apparatus comprising: an adjustment control section that sends a signal to a flow rate adjustment section based on the difference between the flow rate and the flow rate adjustment section; and the flow rate adjustment section connected to the control valve in the B line. (2) A central pipe (a) for feeding mixed gas that penetrates from one end of a cylinder with both ends closed forms a T-shaped branch at the other end inside the cylinder,
The directions of the openings of the branch pipes (b, b') are along the inner wall of the cylinder and in opposite directions, and the openings of the central pipe (a
) A funnel-shaped bulkhead umbrella (c) is provided in the center, the peripheral edge of which is fixed to the cylindrical wall, and the tip of which opens along the central pipe near the penetrating end;
Furthermore, another partition umbrella (d) having a shape opposite to this is provided so that its tip end is fixed to the center pipe and its peripheral edge opens along the cylindrical wall, and an exhaust pipe is provided at the end where the center pipe penetrates. 2. The gas corrosion test apparatus according to claim 1, wherein a secondary mixer is provided in the gas mixing system.