JP3398806B2 - How to prevent water pipe corrosion - Google Patents
How to prevent water pipe corrosionInfo
- Publication number
- JP3398806B2 JP3398806B2 JP20919994A JP20919994A JP3398806B2 JP 3398806 B2 JP3398806 B2 JP 3398806B2 JP 20919994 A JP20919994 A JP 20919994A JP 20919994 A JP20919994 A JP 20919994A JP 3398806 B2 JP3398806 B2 JP 3398806B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- thickness
- hydrogen carbonate
- pipe
- calcium hydrogen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
- F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
- F16L58/04—Coatings characterised by the materials used
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Protection Of Pipes Against Damage, Friction, And Corrosion (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【発明の詳細な説明】Detailed Description of the Invention
【０００１】[0001]
【産業上の利用方法】本発明は水道配管に炭酸カルシウ
ムを主成分とする被膜を形成させて水道配管の腐食を防
止する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing corrosion of a water pipe by forming a film containing calcium carbonate as a main component on the water pipe.
【０００２】[0002]
【従来の技術】従来、水道水に赤水が発生するのは主と
して水道配管が腐食するためであり、赤水発生防止のた
めに種々の対策が採られている。赤水発生防止技術とし
ては苛性ソーダ注入法、ソーダ灰注入法、消石灰注入法
などがある。なかでも、消石灰注入法は単に水道水のｐ
Ｈを調整するだけでなく、カルシウムが配管内の壁面に
おいて炭酸カルシウムを主成分とする膜を形成し、赤水
発生を防止すると推察されている。2. Description of the Related Art Conventionally, red water is generated in tap water mainly because the water pipe is corroded, and various measures are taken to prevent the generation of red water. Red water generation prevention techniques include caustic soda injection method, soda ash injection method, and slaked lime injection method. Among them, the slaked lime injection method is simply p
It is presumed that not only H is adjusted, but also calcium forms a film containing calcium carbonate as a main component on the wall surface in the pipe to prevent the generation of red water.
【０００３】そのため、ｐＨの向上を水質基準内に抑え
ながらカルシウム濃度を大きくするために、先ず、浄水
処理された水道水に炭酸ガスを吹き込み溶解させ遊離炭
酸濃度の大きい水とした後に、消石灰水溶液を注入して
水道水のランゲリア指数を０〜１の所望値にすることが
提案されている（特開平2-194893号公報）。ランゲリア
指数が＋なら水中から炭酸カルシウムが析出する状態、
ーなら水中へ溶出する状態、０なら析出と溶解が同時に
起こっている平衡状態であるとされている。Therefore, in order to increase the calcium concentration while suppressing the improvement in pH within the water quality standard, first, carbon dioxide gas is blown into the purified tap water to dissolve it into water having a high free carbonic acid concentration, and then a slaked lime aqueous solution. Has been proposed to make the Langerian index of tap water to a desired value of 0 to 1 (Japanese Patent Laid-Open No. 2-194893). If the Langerian index is +, the state where calcium carbonate precipitates from water,
If it is −, it is considered to be a state of elution into water, and if it is 0, it is considered to be an equilibrium state in which precipitation and dissolution occur simultaneously.
【０００４】しかし、単にランゲリア指数を一定にする
だけでは、水道配管に炭酸カルシウムを主成分とする被
膜が充分形成されなかったり、過剰な被膜が形成される
不都合がある。However, simply making the Langeria index constant does not lead to insufficient formation of a coating containing calcium carbonate as a main component in the water pipe or an excessive coating.
【０００５】[0005]
【発明が解決しようとする課題】上述のように、消石灰
を注入することにより、形成される炭酸カルシウムを主
成分とする被膜が配管の腐食防止に有効なことが知られ
ている。しかし、炭酸カルシウムを主成分とする被膜は
形成の過程により膜の緻密さが異なることなどから、配
管腐食防止のために被膜の厚みがどの程度必要であるか
については知られておらず、また一旦形成された被膜も
配管内を流れる水道水の性状により容易に消失する。従
って、保護被膜が水道配管内に常に腐食防止に有効でか
つ通水抵抗に影響しない略一定の厚みで存在させ得るよ
うな配水方法が望まれる。As described above, it is known that the film containing calcium carbonate as a main component formed by injecting slaked lime is effective in preventing corrosion of piping. However, since the film containing calcium carbonate as the main component has different denseness depending on the process of formation, it is not known how thick the film is to prevent pipe corrosion, and The coating film once formed easily disappears due to the property of tap water flowing in the pipe. Therefore, there is a demand for a water distribution method in which the protective coating is always effective in preventing corrosion in the water pipe and can be present in a substantially constant thickness that does not affect the water flow resistance.
【０００６】大阪水道局の報告によると、消石灰を注入
し平均２４μの炭酸カルシウムを主成分とする被膜を形
成させたが、消石灰を注入しない場合に比べ１０％程度
しか腐食防止の効果がなかった。According to a report from the Osaka Waterworks Bureau, slaked lime was injected to form an average film of 24 μm containing calcium carbonate as a main component, but the effect of preventing corrosion was only about 10% as compared with the case where slaked lime was not injected. .
【０００７】本発明者等は、種々のカルシウム濃度の水
を通水し、水道配管内に形成される被膜の厚みと腐食に
ついて鋭意研究した結果、炭酸カルシウムを主成分とす
る被膜の厚みが５０μ以上あれば腐食防止に有効なこと
を見出した。The present inventors have conducted diligent research on the thickness and corrosion of a coating formed in a water pipe by passing water having various calcium concentrations, and as a result, the thickness of the coating containing calcium carbonate as a main component is 50 μm. It was found that the above is effective in preventing corrosion.
【０００８】[0008]
【課題を解決するための手段】本発明は、上述の知見に
基づいてなされたものであり、浄水場で浄水処理された
水道水に炭酸水素カルシウムを含有させながら配水する
に当たり、炭酸水素カルシウムで該配水のランゲリア指
数をー１．２〜０．５の範囲に維持しながら、かつ、配
管末端部における炭酸カルシウムを主成分として形成さ
れる被膜の厚みが所定の最大厚みに達した段階で該ラン
ゲリア指数が小さくなるように炭酸水素カルシウムの含
有量を調節し、被膜が溶解して厚みが所定の最小の厚み
に減少した段階で該ランゲリア指数が大きくなるように
炭酸水素カルシウムの含有量を調節することを特徴とす
る水道配管の腐食防止方法である。Means for Solving the Problems The present invention has been made on the basis of the above-mentioned findings. When water is distributed while containing calcium hydrogen carbonate in tap water purified by a water purification plant, calcium hydrogen carbonate is used. While maintaining the Langerian index of the water distribution in the range of -1.2 to 0.5, and at the stage when the thickness of the coating formed mainly of calcium carbonate at the end of the pipe reaches a predetermined maximum thickness, The content of calcium hydrogen carbonate is adjusted so that the Langeria index becomes smaller, and the content of calcium hydrogen carbonate is adjusted so as to increase when the film is dissolved and the thickness is reduced to a predetermined minimum thickness. This is a method for preventing corrosion of water pipes.
【０００９】以下、本発明を詳しく説明する。The present invention will be described in detail below.
【００１０】水道水は、種々の水源より取水した水を浄
水場で水質基準を満たすべく浄水処理され配水池より配
水される。しかし、この水も多くの場合ランゲリア指数
がー１以下であり、水道配管を腐食し赤水が発生するお
それがある。このため消石灰を注入して水質改善をして
配管内に保護膜を形成させるようにするが、遊離炭酸濃
度が低くｐＨ緩衝能が小さい水では、水質基準に定めら
れるｐＨ値から注入する消石灰の量に限度がある。従っ
て、本発明では消石灰および炭酸ガスを用い炭酸水素カ
ルシウムとしてカルシウムを含有させる。こうして水道
水のランゲリア指数をー１．２〜０．５に調整して配水
する。一方、水道配管内の被膜の状態を所定の最小厚み
から所定の最大厚み、即ち腐食を防止するに充分にして
通水抵抗に影響しない厚みに維持するように配管内の被
膜の厚みを監視し、通水する水のランゲリア指数を上記
範囲内で調整する。即ち、一例を示せば、通水初期は比
較的ランゲリア指数の大きい水を配水し、配管壁に炭酸
カルシウムを主成分とする保護膜が形成され易い状態に
するが、配管末端部における被膜の厚みが所定の最大厚
みを越える状態、即ち２００μを越え２５０μに達する
前に該配水のランゲリア指数が小さくなる量、すなわ
ち、ランゲリア指数がー１．２〜ー０．８、好ましくは
ー０．６〜ー０．４になるように炭酸水素カルシウムの
含有量を調節し、被膜がそれ以上成長しないようにす
る。しかし、この操作だけで被膜を一定に維持させるこ
とは極めて困難である。The tap water is purified from the water taken from various water sources at the water purification plant so as to meet the water quality standard, and then distributed from the distribution reservoir. However, in many cases, this water also has a Langerian index of -1 or less, which may corrode water pipes and generate red water. For this reason, slaked lime is injected to improve the water quality to form a protective film in the pipe, but in the case of water with a low free carbon dioxide concentration and a small pH buffering capacity, slaked lime of There is a limit to the amount. Therefore, in the present invention, calcium is contained as calcium hydrogen carbonate using slaked lime and carbon dioxide. In this way, the Langeria index of tap water is adjusted to -1.2 to 0.5 and water is distributed. On the other hand, the thickness of the coating film in the pipe is monitored so that the state of the coating film in the water supply pipe is maintained from the predetermined minimum thickness to the predetermined maximum thickness, that is, the thickness that is sufficient to prevent corrosion and does not affect the water flow resistance. , Adjust the Langerian index of water to be passed within the above range. That is, to give an example, in the initial stage of water flow, water with a relatively large Langerian index is distributed so that a protective film mainly composed of calcium carbonate is easily formed on the pipe wall. Exceeds a predetermined maximum thickness, that is, the amount by which the Langerian index of the distribution water becomes smaller before reaching more than 200μ and 250μ, that is, the Langerian index is -1.2 to -0.8, preferably -0.6 to The content of calcium hydrogen carbonate is adjusted to −0.4 so that the film does not grow any more. However, it is extremely difficult to keep the coating constant only by this operation.
【００１１】このため、配管末端の枝管に形成される被
膜の厚みを定期的に測定することにより、炭酸水素カル
シウムの注入量を調整する。配管内に一旦形成された被
膜が溶解する傾向にあるときは、所定の最小厚みが５０
μに減少する前に、好ましくは１００μ以下になったと
きに、被膜が形成されるよう炭酸水素カルシウムの含有
量を増加し水道水のランゲリア指数が大きくなる量、す
なわち、ランゲリア指数をー０．５〜＋０．４、好まし
くはー０．２〜＋０．２になるように炭酸水素カルシウ
ムの含有量を調節し、被膜厚みを増加させる。Therefore, the injection amount of calcium hydrogen carbonate is adjusted by periodically measuring the thickness of the film formed on the branch pipe at the end of the pipe. If the coating once formed in the pipe tends to dissolve, the prescribed minimum thickness is 50
Before decreasing to 100 μ, preferably when it becomes 100 μ or less, the amount by which the content of calcium hydrogen carbonate is increased so that the film is formed and the Langeria index of tap water becomes large, that is, the Langerian index is −0. The content of calcium hydrogen carbonate is adjusted so as to be 5 to +0.4, preferably -0.2 to +0.2 to increase the film thickness.
【００１２】このように水道水のランゲリア指数を調節
するために必要な炭酸水素カルシウムの含有量は、予め
原水の性状（ランゲリア指数、ｐＨなど）から実験的に
求めておくことにより、消石灰および炭酸ガスの添加量
を随時変更させればよい。Thus, the content of calcium hydrogen carbonate necessary for controlling the Langerian index of tap water is experimentally obtained in advance from the properties of the raw water (Langeria index, pH, etc.) to obtain slaked lime and carbonate. The amount of gas added may be changed at any time.
【００１３】被膜の厚みの測定は、例えば配管の一部に
両端に止水弁を備えたバイパスを設け、該バイパス管を
取り外し行うことができる。その他配管外部より電気的
に或いは超音波を用いるなどして測定することもでき
る。なお、被膜は配水池近傍でやや厚く形成される傾向
があるが、数キロ先の末端枝管においても被膜の厚みは
余り変わらない。適当な末端枝管を決めて定期的に測定
すればよい。口径１３mmの末端管においても形成される
被膜の厚みが２５０μあっても通水抵抗に影響はない
が、被膜の厚みはこの程度に止めるのが好ましい。The thickness of the coating can be measured, for example, by providing a bypass with a water shutoff valve at both ends in a part of the pipe and removing the bypass pipe. Alternatively, the measurement can be performed electrically from outside the pipe or by using ultrasonic waves. The coating tends to be slightly thicker in the vicinity of the reservoir, but the thickness of the coating does not change much even in the terminal branch pipe several kilometers away. A proper end branch tube may be determined and measured periodically. Even if the thickness of the coating formed on the terminal tube having a diameter of 13 mm is 250 μ, it does not affect the water flow resistance, but the thickness of the coating is preferably limited to this level.
【００１４】水道水中に炭酸水素カルシウムを含有させ
る方法としては、予め炭酸水素カルシウム水溶液を製造
して注入する方法がある。炭酸水素カルシウム水溶液の
製造は、例えば先ず消石灰を攪拌手段を有する溶解槽に
投入し、攪拌下槽下部より水供給し槽上部より消石灰の
略飽和水溶液を取り出すことにより消石灰略飽和水溶液
を製造し、これに炭酸含有水を注入することにより行い
得る。また消石灰または炭酸カルシウムの１〜１５％ス
ラリーに炭酸ガスを吹き込むか炭酸含有水を注入するこ
とにより1000ｐｐｍ程度またはそれ以上の炭酸水素カル
シウム水溶液を得ることができる。As a method of containing calcium hydrogen carbonate in tap water, there is a method of previously preparing and injecting an aqueous solution of calcium hydrogen carbonate. The production of calcium hydrogen carbonate aqueous solution, for example, first put slaked lime in a dissolution tank having a stirring means, to produce a substantially saturated aqueous solution of slaked lime by supplying water from the lower portion of the tank under stirring and taking out a substantially saturated aqueous solution of slaked lime, This can be done by injecting carbonated water. Further, by blowing carbon dioxide gas or injecting carbonic acid-containing water into a 1 to 15% slurry of slaked lime or calcium carbonate, an aqueous solution of calcium hydrogen carbonate of about 1000 ppm or more can be obtained.
【００１５】本発明方法は、好ましくは浄水場で行う。
浄水処理された水のｐＨ調整を炭酸水素カルシウム水溶
液または炭酸水素カルシウム水溶液と消石灰水溶液を併
用して行い、水質基準で定められるｐＨ値内でカルシウ
ム濃度を大きくし、水道配管内に保護被膜が形成される
ようにする。尤も、このときの水道水のランゲリア指数
はー１．２〜０．５の範囲内で調整し、被膜が形成され
過ぎたり、急激に溶解しないようにする。被膜の厚みが
２５０μを越すような場合であっても、通水のランゲリ
ア指数をマイナス側に大きくすると短時日のうちに溶解
消失する。従って、通水のランゲリア指数は上記の範囲
内で調整するのが好ましい。The method of the present invention is preferably carried out in a water purification plant.
The pH of purified water is adjusted by using an aqueous solution of calcium hydrogen carbonate or an aqueous solution of calcium hydrogen carbonate together with an aqueous solution of slaked lime to increase the calcium concentration within the pH value specified by the water quality standard, and a protective film is formed in the water pipe. To be done. However, the Langeria index of tap water at this time is adjusted within a range of -1.2 to 0.5 so that the film is not overly formed or is not rapidly dissolved. Even when the thickness of the coating exceeds 250 μ, when the Langeria index of water flow is increased to the negative side, dissolution disappears within a short time. Therefore, it is preferable to adjust the Langerian index of water flow within the above range.
【００１６】他の方法としては、予め炭酸水素カルシウ
ム水溶液を準備することなく、消石灰水溶液と炭酸ガス
または炭酸含有水を注入し（その順序は問わない）、水
道水中で炭酸水素カルシウムを生成させてもよい。As another method, without preparing an aqueous solution of calcium hydrogen carbonate in advance, an aqueous solution of slaked lime and water containing carbon dioxide or carbonic acid are injected (the order does not matter) to produce calcium hydrogen carbonate in tap water. Good.
【００１７】なお、本発明方法は浄水場の配水池出口水
について行われる場合ばかりでなく、高層ビルなどで市
水を受水槽で受けた後高架槽に送り、高架槽から水使用
先に配水するような場合に受水槽から高架槽に至る過程
において、水道水に炭酸水素カルシウム水溶液を注入す
ることにより、或いは消石灰水溶液と炭酸ガスまたは炭
酸含有水を注入することにより行うこともできる。The method of the present invention is not limited to the case of the outlet water of a water distribution reservoir of a water purification plant, but also receives city water in a high-rise building or the like in a receiving tank and then sends it to an elevated tank to distribute the water from the elevated tank to the destination of use. In such a case, in the process from the water receiving tank to the elevated tank, it can be performed by injecting a calcium hydrogen carbonate aqueous solution into tap water or by injecting a slaked lime aqueous solution and carbon dioxide gas or carbonic acid-containing water.
【００１８】[0018]
【実施例】浄水場で浄水処理された水道水はｐＨ７．
０、総アルカリ度２０ｐｐｍ、カルシウム硬度２１ｐｐ
ｍでランゲリア指数ー２．４であった。この水道水を受
水した受水槽から高架槽に送られる水に炭酸ガスおよび
消石灰水溶液を注入して、高架槽から水使用先に通水し
た。水使用先の手前の配管に、両端に止水弁を有する該
配管と同じ口径の長さ３０cmのバイパス管（鉄管）を取
り付け４ヶ月毎に取り外し被膜の状態を観察した。Example: The tap water treated at the water purification plant has a pH of 7.
0, total alkalinity 20ppm, calcium hardness 21pp
The m / m was Langerian index of -2.4. Carbon dioxide gas and a slaked lime aqueous solution were injected into the water sent from the water receiving tank that received this tap water to the elevated tank, and water was passed from the elevated tank to the water use destination. A bypass pipe (iron pipe) having a diameter of 30 cm and having the same diameter as the pipe having water shut-off valves at both ends was attached to the pipe before the water use destination, and the state of the coating film was observed every 4 months.
【００１９】最初水量１０ｍ3／Ｈに対し、炭酸ガスを
３５ｐｐｍ，消石灰を３０ｐｐｍ注入してｐＨ８．３、
カルシウム硬度６２ｐｐｍ、アルカリ度６０ｐｐｍ、ラ
ンゲリア指数０の水として通水した。Initially, with respect to a water amount of 10 m 3 / H, carbon dioxide gas of 35 ppm and slaked lime of 30 ppm were injected to obtain a pH of 8.3.
Water having a calcium hardness of 62 ppm, an alkalinity of 60 ppm and a Langerian index of 0 was passed.
【００２０】４ヶ月後におけるバイパス管に形成された
被膜の厚みは約２００μであった。そこで炭酸ガスの注
入を止め、消石灰の注入量を５ｐｐｍに減らし、ランゲ
リア指数−１．０の水として通水を続けた。４ヶ月後の
被膜の厚みは約６０μであっ た。さらに、炭酸注入量
を２０ｐｐｍ、消石灰注入量を１８ｐｐｍとしランゲリ
ア指数ー０．２の水を通水した。４ヶ月後の被膜の厚み
は約１００μであった。そして、この間の赤水発生は観
測されなかった。The thickness of the coating formed on the bypass pipe after 4 months was about 200 μm. Therefore, the injection of carbon dioxide gas was stopped, the injection amount of slaked lime was reduced to 5 ppm, and water was continued as water with a Langerian index of -1.0. The thickness of the coating after 4 months was about 60μ. Further, the carbon dioxide injection amount was 20 ppm and the slaked lime injection amount was 18 ppm, and water having a Langerian index of -0.2 was passed. The thickness of the coating film after 4 months was about 100 μm. No red water generation was observed during this period.
【００２１】[0021]
【発明の効果】水道水のｐＨ調整を消石灰水溶液を用い
て行うこと、また消石灰水溶液と炭酸含有水を用いて炭
酸水素カルシウムに転換して水道水のランゲリア指数を
調整することも知られている。しかし、単にランゲリア
指数を一定にするだけでは、水道配管に炭酸カルシウム
を主成分とする被膜が充分形成されなかったり、過剰な
被膜が形成される不都合がある。It is also known that the pH of tap water is adjusted using an aqueous slaked lime solution and that the Langerian index of the tap water is adjusted by converting the aqueous slaked lime solution and carbonated water into calcium hydrogen carbonate. . However, if the Langerian index is simply kept constant, there is a problem that a coating film containing calcium carbonate as a main component is not sufficiently formed in the water pipe or an excessive coating film is formed.
【００２２】本発明によれば、水道配管内に腐食を防止
するに充分にして、かつ、通水抵抗に影響しない厚みの
被膜を配管ないに維持することができる。その結果、水
道管の腐食が防止され赤水が生じることがない。According to the present invention, it is possible to maintain a coating film in a water pipe having a thickness sufficient to prevent corrosion and not affecting the water flow resistance. As a result, corrosion of the water pipe is prevented and red water is not produced.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) C23F 11/18 C02F 1/00 F16L 58/04 ─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. 7 , DB name) C23F 11/18 C02F 1/00 F16L 58/04
Claims (2)
カルシウムを含有させ配水するに当たり、該配水のラン
ゲリア指数をー１．２〜０．５の範囲に維持しながら、
かつ、配管末端部における炭酸カルシウムを主成分とし
て形成される被膜の厚みが所定の最大厚みに達した段階
で該ランゲリア指数が小さくなるように炭酸水素カルシ
ウムの含有量を調節し、該被膜が溶解して厚みが所定の
最小厚みに減少した段階で該ランゲリア指数が大きくな
るように炭酸水素カルシウムの含有量を調節することを
特徴とする水道配管の腐食防止方法。1. When tap water treated at a water purification plant contains calcium hydrogen carbonate and is distributed, while maintaining the Langerian index of the distribution water in the range of -1.2 to 0.5,
Moreover, when the thickness of the coating formed mainly of calcium carbonate at the end of the pipe reaches a predetermined maximum thickness, the calcium hydrogen carbonate content is adjusted so that the Langerian index becomes small, and the coating dissolves. Then, the content of calcium hydrogen carbonate is adjusted so that the Langerian index becomes large when the thickness is reduced to a predetermined minimum thickness.
び、所定の最小厚みが１００〜５０μである請求項１に
記載の水道配管の腐食防止方法。2. The method for preventing corrosion of water pipes according to claim 1, wherein the predetermined maximum thickness is 150 to 250 μ and the predetermined minimum thickness is 100 to 50 μ.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20919994A JP3398806B2 (en) | 1994-08-09 | 1994-08-09 | How to prevent water pipe corrosion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20919994A JP3398806B2 (en) | 1994-08-09 | 1994-08-09 | How to prevent water pipe corrosion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0853782A JPH0853782A (en) | 1996-02-27 |
| JP3398806B2 true JP3398806B2 (en) | 2003-04-21 |
Family
ID=16569000
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20919994A Expired - Fee Related JP3398806B2 (en) | 1994-08-09 | 1994-08-09 | How to prevent water pipe corrosion |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3398806B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010137224A (en) * | 2010-02-12 | 2010-06-24 | Kureha Engineering Co Ltd | Method for cleaning water |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3105309B2 (en) * | 1991-10-09 | 2000-10-30 | 呉羽化学工業株式会社 | Method and apparatus for improving tap water |
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1994
- 1994-08-09 JP JP20919994A patent/JP3398806B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0853782A (en) | 1996-02-27 |
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