JP2002241976A - Method for preventing and removing patina in metallic member using copper or copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of patina in copper or a copper alloy widely used for piping and faucet apparatuses for water supply, and further, to remove generated patina. SOLUTION: In the method for preventing and removing patina in a metallic member using copper or a copper alloy used for a water path, the water path is provided with a controlling means for controlling the concentration of dissolved oxygen in water at least on remaining to 6 to 7.5 mg/l, and the concentration of free carbonic acid to the outside of the range of 5 to 30 mg/l.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing and removing patina generated in copper or copper alloy water supply piping, faucet equipment, hot water supply equipment and cooling tower piping.

[0002]

2. Description of the Related Art Copper and copper alloys are materials having excellent corrosion resistance and are widely used for water supply piping and faucet equipment. However, even if it is a copper alloy material having excellent corrosion resistance, a long-term use causes corrosive and greenish blue to occur, which causes blue water. Patina grows gradually as it is produced for a long period of time, and drops off due to water currents. The fallen patina may bite into the sliding portion of the valve, causing the valve to malfunction and water to be unable to stop or discharge. In addition, when biting into the sliding portion of the temperature controller, there is a possibility that the temperature cannot be adjusted properly.

[0003]

SUMMARY OF THE INVENTION The present invention has been made based on the above-mentioned problems, and is directed to a method for preventing patina of a metal member using copper or a copper alloy used in a water path. Dissolved oxygen concentration of 6-7.5 mg /
The method for preventing patina according to the present invention is characterized in that an adjusting means for adjusting the concentration of l and free carbonic acid out of the range of 5 to 30 mg / l is provided in the water path.

[0004] Copper alloys generally used for water supply pipes, faucets and the like produce patina due to their corrosion. As a result of our intensive studies, it has been found that the occurrence of patina is less likely to occur in water with significantly high corrosiveness, and the dissolved oxygen concentration in the water is 6-7.
Use of water with a concentration of 5 mg / l and a free carbonic acid concentration of 5 to 30 mg / l, discover that green-blue is likely to be generated and generated, and adjust the water quality so that it is out of the range where green-blue is easily generated. Then, a method of minimizing the occurrence of patina is proposed. FIG. 1 shows the concentration of dissolved oxygen, the concentration of free carbonic acid, and the state of generation of patina, since the state of patina generation differs depending on various water qualities. As shown in FIG. The water quality conditions that can be achieved, namely, the dissolved oxygen concentration of 6 to 7.5 mg / l and the free carbonic acid concentration of 5 to 30 mg / l, are on a delicate balance.

In the process of producing patina, first, the copper alloy is corroded and eluted in the water as Cu ⁺ ions. Eluted C
The u ⁺ ions are oxidized and mostly cuprous oxide: Cu ₂ O
, And a part thereof generates copper oxide: CuO to form an oxide film on the surface of the copper alloy. The oxide film re-elutes and elutes in water as Cu ²⁺ ions. Cu ²⁺ ions react with oxygen, carbon dioxide, and water to produce patina: Cu ₂ CO ₃
(OH) ₂ is produced.

The above reaction is more likely to occur as the concentration of dissolved oxygen and free carbonic acid in water is higher, and the reaction is more likely to occur as the concentration of dissolved oxygen is higher. But,
The patina produced by the reaction of (1) becomes easier to elute into water as the dissolved oxygen concentration or the free carbonic acid concentration becomes higher, and the patina produced by the reaction (1) flows out together with the water.

[0007] That is, for the production of patina, the dissolved oxygen and free carbonic acid in the water need to have a certain concentration, but if the concentration is too high, the production of patina is suppressed.

The generation of patina greatly depends on the dissolved oxygen and free carbonic acid concentration in the water.
Groundwater such as underground water generally has a low dissolved oxygen concentration of 5 mg / l or less. On the other hand, tap water that uses surface water such as river water as a water source generally has a high dissolved oxygen concentration of about 8 mg / l or more, and often contains almost no free carbonic acid.
For example, when exposed to the air atmosphere, the dissolved oxygen concentration increases, and the water becomes almost free of free carbonic acid. That is,
Even for water with a water quality condition that can produce patina, the concentration of free carbonic acid can be reduced by a relatively simple method such as positively contacting the atmosphere, making it possible to change to water that is resistant to patina. It is.

The production of patina proceeds by a series of reactions (1) to (3), but this reaction cannot be established unless water remains. In other words, the conditions for the green-blue production are the presence of the indicated water quality conditions under which the reaction proceeds and the time during which the water stays, such as at night. In the state where water is continuously flowing through the pipes and faucets that are always in the water path using water, or in the state where water is used regularly, the pipes must be connected before the reaction is completed. ， Water in the faucet equipment leaks out, and patina is not easily generated.

[0010] The adjusting means may be an oxygen supply means and / or a carbon dioxide supply means, and may be prevented by increasing the concentration, or may be an oxygen removal means and / or a carbon dioxide removal means. It can also be prevented by lowering the concentration.

Further, in the method for removing patina from a metal member using copper or a copper alloy used in a water path, at least a dissolved oxygen concentration of water at the time of residence is 6 to 7.5 mg / l and a free carbonic acid concentration is 5 to 30 mg. A method for removing a patina of a metal member using copper or a copper alloy, wherein a water quality adjusting means for adjusting the water quality outside the range of / l is provided in the water supply path.

By linking the means for measuring the dissolved oxygen concentration and the free carbonic acid concentration in the water with the water quality adjusting means, it is possible to efficiently prevent patina.

Further, in the method for removing a patina from a metal member using copper or a copper alloy used in a water path, at least a dissolved oxygen concentration of water at the time of residence is 6 to 7.5 mg / l and a free carbonic acid concentration is 5 to 30 mg. A method for removing a patina of a metal member using copper or a copper alloy, wherein a water quality adjusting means for adjusting the water quality outside the range of / l is provided in the water supply path.

When the dissolved oxygen concentration or free carbonic acid concentration in the water is out of the applicable range of the patina production, the patina dissolution rate becomes faster than the patina production rate, so that the resulting patina is easily eluted and the patina is eluted. It can be removed.

The water quality adjusting means is an oxygen supply means and / or a carbon dioxide supply means.

Furthermore, the higher the above-mentioned respective concentrations, the more green and blue are eluted, so that the dissolved oxygen concentration is adjusted to 7.5 by the adjusting means.
It is desirable that the concentration of free carbonic acid be higher than 30 mg / l, or that the concentration of free carbonic acid be higher than 7.5 mg / l and that the concentration of free carbonic acid be higher than 30 mg / l. .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the concept of the method for preventing patina and the removal of patina according to the present invention is to adjust the dissolved oxygen concentration and the free carbonic acid concentration in water, which are the conditions for patina, to a concentration setting at which patina is difficult to generate. Or controlling the concentration at which the produced patina is eluted.

Water flowing through water supply pipes and faucet equipment follows a closed path except for a receiving tank and an elevated water tank.
Gases such as oxygen and carbon dioxide remain dissolved in water until they flow out to an open tap end. Even in the water in the receiving tank and the elevated water tank, the movement of gas occurs only at the interface between water and the atmosphere, and the movement speed is relatively slow. Therefore, in a state in which water stays or in a state close thereto, gas exchange is unlikely to occur.

Therefore, even if water supplied from a well or a tap is introduced into a water receiving tank, an elevated water tank, or another tank to be used, the water quality depending on the dissolved gas hardly changes.

Therefore, as a method for positively causing a change in water quality in which greenish blue is unlikely to occur, for example, in equipment using a tank such as a water receiving tank or an elevated water tank, the water in the tank is used as a means for adjusting the water quality. Bubbling gas other than carbon dioxide, such as air, nitrogen, argon, etc., or using a stirrer to increase the amount of water that can come into contact with air can increase the free carbon dioxide dissolved in the water. The concentration can be reduced, the dissolved oxygen concentration can be increased, and the generation of patina can be prevented.

If there is no tank equipment such as a water receiving tank or an elevated water tank, a device for bubbling is installed in a water supply pipe or a faucet device to reduce the concentration of free carbonic acid dissolved in water in the same manner, thereby dissolving dissolved water. What is necessary is just to raise oxygen concentration. In addition, monitoring of the dissolved oxygen concentration of water does not always perform bubbling, but can perform a minimum bubbling operation for performing necessary water quality change, thereby enabling efficient water quality control.

The gas dissolved in water is determined by Henry's law.
If the temperature is high, the amount will decrease. If the water temperature is raised in a place where water is open, such as in a tank, the dissolved free carbonic acid can be easily removed and its concentration can be reduced, and if the water temperature is raised, the diffusion of water will increase. Since the exchange of the dissolved gas can be accelerated, the concentration can be adjusted outside the range where the green and blue are easily generated. For example, a heating device such as a sheathed heater may be provided in equipment of a tank such as a water receiving tank or an elevated water tank to adjust the temperature.

In general, the frequency of use of water is closely linked to human life. Water is used during the day from morning to night, but during the night from late night to early morning, almost no water is used, and the water in the pipes and faucets, which are water paths, stays for a long time, Pale blue is produced in water and adheres to the inner surface of pipes and faucets and grows easily. Therefore, at night when the water tends to stay, use the above-mentioned means and continuously prevent water from staying as much as possible. Alternatively, the generation of patina can also be suppressed by periodically flowing water.

Further, once patina is formed in the water supply pipe or faucet equipment, it is difficult to remove the patina. However, if the free carbonic acid concentration of the used water is increased, the corrosiveness to copper and copper alloy is increased. As described above, the amount of green and blue elution also increases,
Green and blue can be removed.

FIG. 2 shows the free carbonic acid concentration and the amount of generated and removed patina, and when the free carbonic acid concentration is higher than 30 mg / l, the removed amount exceeds the generated amount. Since it becomes dominant, it is desirable to set the density higher when removing patina. In this case, the dissolved oxygen concentration is a concentration at which patina is easily generated. Also, the dissolved oxygen concentration shows the same tendency. When the concentration exceeds the concentration range in which green and blue are easily generated, the green and blue is removed, and the removal amount becomes larger at a higher concentration.

It should be noted that water having an increased free carbonic acid concentration is not toxic to the human body and can be adapted for use in water supply facilities used for drinking water and the like. The free carbon concentration in the water gradually decreases only by leaving the water in an open place, and it is no different from the quality of the water before the treatment. A method of bubbling carbon dioxide gas in a tank such as a water tank or an elevated water tank is effective. Alternatively, if the gas phase portion in the tank is filled with carbon dioxide, the carbon dioxide dissolves in the water and the free carbon dioxide concentration can be increased. In addition, even if the dissolved oxygen in the water is increased, the effect of suppressing patina can be expected. Further, when the dissolved oxygen concentration is increased, patina can be eluted similarly to free carbonic acid. May be dissolved by similar means.

When it is difficult to install a carbon dioxide gas bubbling facility as described above, a carbonate such as sodium bicarbonate or sodium carbonate is put into water to generate carbon dioxide in the water and release it. Carbon dioxide concentration can be increased. In addition, when an acid is simultaneously introduced into water as a neutralizing agent, carbon dioxide can be generated more efficiently, and the concentration of free carbon dioxide can be increased.

In order to increase the amount of green and blue eluted, it is possible not only to increase the concentration of free carbonic acid but also to lower the pH. FIG. 3 is a graph showing the solubility of pH and patina. The lower the pH, the higher the solubility, which is desirable for removal of patina. As a method for lowering the pH, the addition of an acid to water or the electrolysis of water and the flow of acidic water through a piping system can remove patina in piping and faucets.

Since the removal of patina which increases the concentration of dissolved oxygen and free carbonic acid is also a condition under which corrosion proceeds, it is necessary to confirm that removal from the start of removal, for example, the outflow of blue water from the water discharge port is stopped. If possible, it is desirable to readjust the water quality to a range that contributes to prevention of generation at low concentrations. That is, when the generation of green and blue has progressed, removal is performed to increase the density. In the early stage of the generation, it is desirable to remove gradually while suppressing the generation at a low concentration.

Now, the present invention will be described in further detail with reference to Examples. Table 1 shows that when a bronze disk having a diameter of 25 mm shown in FIG. 4 was immersed for 30 days in a pipe route in an environment where patina was likely to occur, an elevated water tank connected to the pipe route was used. It shows the results of a case where a bubbling device (air was supplied at 1 to 5 L / min) was installed and water quality was improved and a case where water quality was not improved. 4 shows a state before immersion, FIG. 5 shows a state without bubbling, and FIG. 6 shows a state with bubbling. FIG. 2B is a diagram schematically showing the state of FIG. It can be seen that patina was not observed in the water quality improved.

[0031]

[Table 1]

The present invention can be suitably used for a water supply system using tap water, a cooling tower, hot water heating, and the like, and can be applied to a system using medium water such as rainwater.

[0033]

According to the present invention, by controlling the concentration of dissolved oxygen and the concentration of free carbonic acid, the generation of patina can be prevented, and the generated patina can also be removed. Can be done.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing a relationship among a dissolved oxygen concentration, a free carbonic acid concentration, and water quality at which patina is generated.

FIG. 2 is a diagram showing the relationship between the concentration of free carbonic acid and the amount of green and blue produced and removed.

FIG. 3 is a graph showing the relationship between the solubility of patina and pH.

FIG. 4 is a diagram showing a sample used in an example of the present invention, and FIG. 4 (B) is a diagram schematically showing FIG.

FIG. 5 is a diagram showing a sample after the sample of the example of the present invention is immersed in water that is not improved in water quality, and FIG.
(A) It is the figure which showed the figure typically.

FIG. 6 is a diagram showing a sample after the sample of the example of the present invention is immersed in water with improved water quality, and FIG. 6 (B) is a diagram schematically showing FIG.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Hiroshi Sato Inventor Hiroshi Nojima 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture (72) Inventor Hiroshi Nojima 2 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture 1-chome No. 1-1 Toto Kiki Co., Ltd. F-term (reference) 3H024 DA01 DA10 4K062 AA10 CA10 DA10 FA05 FA16 GA01

Claims (9)

[Claims] 1. A method for preventing a patina of a metal member using copper or a copper alloy used in a water path, wherein at least the dissolved oxygen concentration of water at the time of residence is 6 to 7.5 mg / l and the free carbonic acid concentration is 5 to 30 mg. A patina prevention method, characterized in that an adjusting means for adjusting out of the range of / l is provided in the water path. 2. An apparatus according to claim 1, wherein said adjusting means is an oxygen supply means and / or a carbon dioxide supply means.
A method for preventing patina of a metal member as described in the above. 3. An apparatus according to claim 1, wherein said adjusting means is an oxygen removing means and / or a carbon dioxide removing means.
A method for preventing patina of a metal member using the copper or copper alloy described in the above. 4. A means for measuring the concentration of dissolved oxygen and the concentration of free carbonic acid in water, and the dissolved oxygen concentration as a result of the measurement is 6 to 7.
A patina of a metal member made of copper or a copper alloy, which is activated when the concentration of 5 mg / l and the free carbonic acid are in the range of 5 to 30 mg / l, and has water quality control means controlled to control the water quality outside the range. Prevention method. 5. A method for removing a patina of a metal member using copper or a copper alloy used in a water path, wherein at least a dissolved oxygen concentration of water at the time of residence is 6 to 7.5 mg / l and a free carbonic acid concentration is 5 to 30 mg. A method for removing patina from a metal member using copper or a copper alloy, wherein a water quality adjusting means for adjusting the water quality to outside the range of / l is provided in the water supply path. 6. The control device according to claim 5, wherein the adjusting device is an oxygen supplying device and / or a carbon dioxide supplying device.
A method for removing patina from a metal member using the copper or copper alloy described in the above. 7. The dissolved oxygen concentration is adjusted to 7.
7. The method according to claim 5, wherein the amount is higher than 5 mg / l.
A method for removing patina from a metal member using the copper or copper alloy described in the above. 8. The free carbonic acid concentration of 30 by the adjusting means.
7. The method for removing a patina from a metal member using copper or a copper alloy according to claim 5, wherein the concentration is higher than mg / l. 9. A method for adjusting the dissolved oxygen concentration to 7.
5 mg / l and the free carbonic acid concentration is 30 mg / l
7. The method for removing patina of a metal member using copper or a copper alloy according to claim 5, wherein the value is set to be higher than 1.