JP2021188884A - Pipe cleaning method - Google Patents

Abstract

To provide a pipe cleaning method capable of efficiently and reliably cleaning dirt derived from the biofilm of pipes, such as a pipe connected to a facility such as a bathtub, and also capable of suppressing foaming during cleaning and rinsing of pipes.SOLUTION: A pipe cleaning method comprises, after contacting dirt adhering to the inside of a pipe with a cleaning solution containing (a) percarbonate, (b) reducing agent and water for a predetermined time, rinsing the inside of the pipe with water having more than twice the total capacity of the pipe.SELECTED DRAWING: None

Description

The present invention relates to a method for cleaning pipes.

Large bathtubs used in hospitals, occupancy facilities, hot spring inns, public baths, etc. are generally subjected to circulation purification treatment in order to effectively use bathtub water (hot water). The circulation of bathtub water is performed, for example, by connecting two water passages bored in the bottom surface or the side surface of the bathtub with a circulation pipe and using a circulation pump. Filters (hair catchers), filters, heat exchangers, etc. that remove foreign substances such as hair, towel cloth, and dust are provided in the circulation path composed of pumps and pipes. In addition, chlorine disinfection may be performed to suppress the growth of pathogenic bacteria such as Legionella spp.

The pipes arranged in the circulation path are generally installed in a narrow machine room, are difficult to wash, and cannot be washed frequently like a bathtub, so slime and scale adhering to the inside of the pipes tend to grow. Adhesion of slime and scale in the pipe leads to the generation of germs, so efficient cleaning is desired to maintain a hygienic environment.

Patent Document 1 describes a step of treating scales and slimes adhering to the inner surface of water-based equipment, devices, pipes, etc. with an aqueous solution of an inorganic acid or an organic acid, and without discharging the liquid used in the step from the system. A method for chemically removing scale and slime is disclosed, which comprises a step of adding and mixing a solution of sodium percarbonate in sodium peroxide, sodium percarbonate or stabilized chlorine dioxide water.
Patent Document 2 discloses a bath kettle cleaning agent composed of an acid or an acid salt and a percarbonate.
In Patent Document 3, in a method for cleaning the inside of a pipe, the inside of the pipe is brought into contact with a persulfate or an aqueous solution containing a persulfate and a surfactant, and then the persulfate, a surfactant and an alkali percarbonate are described. A method for cleaning a pipe in contact with an aqueous solution containing salt is disclosed.
Patent Document 4 discloses a solid cleaning composition for a hard surface having bactericidal activity, which contains a predetermined inorganic peroxide, a cationic bactericide, a carbonate or a foaming agent composed of a bicarbonate or a solid acid, and has bactericidal performance. Has been done.

Japanese Unexamined Patent Publication No. 51-037870 Japanese Unexamined Patent Publication No. 61-207500 Japanese Unexamined Patent Publication No. 2006-110213 Japanese Unexamined Patent Publication No. 11-035987

INDUSTRIAL APPLICABILITY The present invention can efficiently and reliably clean pipes, for example, stains derived from biofilms of pipes connected to equipment such as bathtubs, and suppress foaming during cleaning and rinsing of pipes. Provide a method of cleaning pipes that can be used.

In the present invention, a cleaning liquid containing (a) a percarbonate, (b) a reducing agent and water [hereinafter, also referred to as a cleaning liquid of the present invention] is brought into contact with the dirt adhering to the inside of the pipe for a predetermined time, and then the above-mentioned pipe is used. The present invention relates to a method of cleaning the pipe by rinsing the inside of the pipe with an amount of water more than twice the total capacity.

Further, the present invention contains (a) a percarbonate [hereinafter referred to as (a) component] and (b) a reducing agent [hereinafter referred to as (b) component], and is used in the cleaning method of the present invention. Regarding the cleaning agent composition for piping.

According to the present invention, dirt derived from biofilm of pipes, for example, pipes connected to equipment such as bathtubs, can be efficiently and surely washed, and foaming during washing and rinsing of pipes. A method for cleaning a pipe and a composition for cleaning a pipe used for the method are provided.
In the present invention, the biofilm of the pipe can be efficiently washed, and foaming during cleaning and rinsing of the pipe can be suppressed. Disadvantages such as deterioration of workability such as air lock are reduced, and for example, the number of rinses can be reduced.

Schematic diagram showing an example of a circulation bath system for cleaning the piping of the present invention.

The component (a) is a percarbonate. The component (a) is a percarbonate alkali metal salt from the viewpoint of detergency against stains derived from biofilm (hereinafter, also referred to as detergency) and suppression of foaming during work (hereinafter, also referred to as foaming inhibitory property). preferable. As the component (a), sodium percarbonate is more preferable.

The concentration of the component (a) in the cleaning liquid of the present invention is preferably 100 ppm or more, more preferably 200 ppm or more, still more preferably 500 ppm or more, still more preferably 800 ppm or more, and from the viewpoint of detergency and foaming inhibitory property. It is preferably 10000 ppm or less, more preferably 8000 ppm or less, still more preferably 6000 ppm or less, still more preferably 4000 ppm or less.

(B) The component is a reducing agent. The reducing agent referred to in the present invention may be a compound having a reducing action of a transition metal.
The component (b) includes (b1) a compound having an endiol structure, for example, ascorbic acid or a salt thereof, vitamin C, tannic acid, erythorbic acid or a salt thereof, and (b2) a hydroxylamine, for example, N, N-diethylhydroxylamine. , (B3) phenolic reducing agents such as gallic acid, methylhydroquinone, dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, methoxyhydroquinone, chlorohydroquinone, and (b4) other reducing agents such as ascorbic acid derivatives or salts thereof. Examples thereof include a reducing agent selected from hydrosulfite, pyrosulfite, sulfite, hydrogen sulfite, thiosulfate, and thiourea dioxide.
As the component (b), ascorbic acid and a salt thereof, and one or more compounds selected from vitamin C are preferable from the viewpoints of detergency, foaming inhibitory property, and ease of application in commercialization.

The concentration of the component (b) in the cleaning liquid of the present invention is preferably 10 ppm or more, more preferably 50 ppm or more, still more preferably 100 ppm or more, still more preferably 300 ppm or more, still more, from the viewpoint of detergency and foaming inhibitory property. It is preferably 500 ppm or more, more preferably 1000 ppm or more, still more preferably 2500 ppm or more, and preferably 100,000 ppm or less, more preferably 50,000 ppm or less, still more preferably 30,000 ppm or less, still more preferably 10,000 ppm or less, still more preferably 5000 ppm. It is as follows.

From the viewpoint of detergency and foaming inhibitory property, the cleaning liquid of the present invention preferably further contains (c) one or more compounds selected from organic acids and salts thereof [hereinafter referred to as (c) component]. Examples of the component (c) include malonic acid, malic acid, 3-hydroxypropionic acid, succinic acid, lactic acid, tartrate acid, glycolic acid, maleic acid, and fumaric acid. As the component (c), one or more compounds selected from tartaric acid, succinic acid, malic acid and salts thereof are preferable from the viewpoint of detergency and foaming inhibitory property.

When the cleaning liquid of the present invention contains the component (c), the concentration of the component (c) in the cleaning liquid is preferably 100 ppm or more, more preferably 500 ppm or more, still more preferably 1000 ppm or more, and more, from the viewpoint of cleaning property. It is more preferably 2500 ppm or more, and from the viewpoint of foaming inhibitory property, it is preferably 10000 ppm or less, more preferably 8000 ppm or less, still more preferably 6000 ppm or less, still more preferably 4000 ppm or less.

In addition to the components (a), (b), and (c), the cleaning solution of the present invention contains, for example, components such as a surfactant, a chelating agent, an enzyme, and an antifoaming agent, as long as the effects of the present invention are not impaired. Can be contained.

The pH of the cleaning solution of the present invention is preferably 3 or more, more preferably 3.5 or more, still more preferably 3.8 or more, and preferably 11 or less, more preferably 6 from the viewpoint of detergency and foaming inhibitory property. Below, it is more preferably 5 or less.

The temperature of the cleaning liquid of the present invention is preferably 20 ° C. or higher, more preferably 35 ° C. or higher, and preferably 60 ° C. or lower, more preferably 45 ° C. or lower.

In the cleaning method of the present invention, the cleaning liquid of the present invention is brought into contact with the dirt adhering to the inside of the pipe for a predetermined time. The stain may be a stain containing a biofilm. Therefore, the cleaning method of the present invention may be a cleaning method in which the cleaning liquid of the present invention is brought into contact with the dirt containing the biofilm adhering to the inside of the pipe for a predetermined time. The predetermined time, that is, the time for contacting the cleaning liquid of the present invention with the dirt is preferably 5 minutes or more, more preferably 10 minutes or more, still more preferably 20 minutes or more, and from the viewpoint of detergency and foaming inhibitory property. It is preferably 100 minutes or less, more preferably 60 minutes or less, still more preferably 45 minutes or less.

In the cleaning method of the present invention, it is preferable that the cleaning liquid after cleaning is adjusted to pH 5 or more, further 6 or more, 9 or less, and further 8 or less, and then discharged from the pipe.

In the cleaning method of the present invention, for example, in the case of a pipe connected to a drainage tank, a bathtub, or the like, the pH of the cleaning liquid is preferably 3 or more and 6 or less, more preferably 3 or more and 5 or less, and then the pipe is brought into contact with the pipe. It is preferable that the washing drainage liquid is discharged from the water and stored in a drainage tank, a bathtub, or the like, and the pH of the washing drainage liquid is preferably adjusted to 5 or more and 9 or less, more preferably 6 or more and 8 or less, and then discharged. In this method, the dirt in the pipe is dissolved in the washing water at the initial stage, and then the dirt dissolved by adjusting the pH is deposited as a water-insoluble matter of an appropriate size, so that the dirt is less likely to remain in the pipe, and the dirt is less likely to remain in the pipe. It is considered that the waste can be easily discharged to the outside of the pipe, the cleaning efficiency can be further improved, the post-treatment such as separating the dirty portion from the discharged liquid as sludge can be facilitated, and the load on the environment can be reduced.

In the cleaning method of the present invention, the cleaning liquid of the present invention is brought into contact with the dirt adhering to the inside of the pipe to be cleaned for a predetermined time, and then the inside of the pipe is rinsed with water in an amount of at least twice the total capacity of the pipe. Rinsing is preferably performed multiple times. After cleaning the pipes, for example, in a circulating bathtub, when restarting the operation, the operation is performed while maintaining a low concentration of hypochlorite or the like and disinfecting the bathtub water. At that time, if the operation is performed with the cleaning solution of the present invention remaining excessively, the effect of hypochlorite is reduced, so it is necessary to rinse until the effect of hypochlorite is not affected. In the cleaning method of the present invention, suppressing foaming of the cleaning liquid leads to suppression of excessive foaming that occurs when rinsing with a certain amount of water, and even if the number of rinses increases, the rinsing efficiency may be impaired. No.
In the present invention, rinsing is performed a plurality of times, and the amount of water used for each rinsing is 1 times or more, further 2 times or more, further 3 times or more the total capacity of the pipe from the viewpoint of foaming inhibition, and It is preferably 4 times or less, and more preferably 5 times or less.
The temperature of the water to be rinsed can be, for example, 5 ° C. or higher and 60 ° C. or lower from the viewpoint of detergency and foaming inhibitory property.

The water used for the cleaning liquid and the rinsing water of the present invention is not particularly limited, but tap water, groundwater, hot spring water, ion-exchanged water, distilled water and the like can be used.

The piping may form at least part of the circulation path.
The circulation path may include a bathtub connected to the pipe.
The circulation path may include a heat exchanger connected to the piping.
The circulation path may include dust collecting means and / or filtering means connected to the pipe.
As these bathtubs, heat exchangers, dust collecting means, and filtering means, known ones used in hot water supply systems and the like can be adopted.

In the cleaning method of the present invention, the piping forms at least a part of the circulation path, and the cleaning liquid can be circulated and brought into contact with each other. Further, after the pipe forms at least a part of the circulation path and the cleaning liquid is circulated and brought into contact with the pipe, the cleaning liquid can be discharged from the pipe and then rinsed.

The present invention will be described with reference to FIG. FIG. 1 is a schematic view showing an example of a circulation bath system that performs the method for cleaning pipes of the present invention. In FIG. 1, 1 is a pipe, 2 is a bathtub, 3 is a heat exchanger, 4 is a filter, 5 is a hair catcher, 6 is a sealing plug, and 7 is a separating device installed as needed (for example, Filters, centrifuges, etc.), and the arrows indicate the direction of travel of wash water or water for rinsing (hereinafter, also referred to as rinse water). In the system of FIG. 1, the pipe 1 and the bathtub 2 are connected to form a circulation path. A heat exchanger 3 connected to a pipe, a filter 4, and a hair catcher 5 as a dust collecting means are arranged in the circulation path. In the system of FIG. 1, a pump (not shown) is set to send out wash water and rinse water. In FIG. 1, the washing water is conveyed from the pipe 1 to the bathtub 2, further discharged from the bathtub 2 and conveyed to the pipe 1, and moves along the circulation path in the direction of the arrow to wash the pipe. The circulation time may be the contact time and can be selected from the above range. The pH and temperature of the cleaning solution can be selected from the above ranges. In the present invention, the pH of the circulating cleaning liquid is preferably 3 or more and 5 or less. After the cleaning liquid has been contacted for a predetermined time, the circulation is stopped, a pH adjuster is added as necessary to adjust the pH to more than 5 and 9 or less, and then the sealing stopper 6 is released to precipitate a solid. Minutes are discharged from the bathtub 2, for example, removed by filtration or the like with a separator 7 if necessary, and then discharged from this system. After the cleaning liquid is discharged, the amount of rinse water that is at least twice the total capacity of the pipe 1 is supplied to the circulation path to rinse the pipe 1, the bathtub 2, and the like. When the pipes form a circulation path as shown in FIG. 1, the supply of the rinse water is temporarily stopped when the amount corresponding to the total capacity of the pipe 1 is supplied from the point where the supply of the rinse water is started, and the rinse water is supplied. It may be circulated and rinsed for a predetermined time. This one-time circulation rinsing corresponds to rinsing with an amount of water that is once the total capacity of the pipe 1. After the circulation rinsing for a predetermined time is completed, the rinse water is discharged, and by performing an additional rinse at least once in the same manner, the pipe can be rinsed with more than twice the total capacity of the pipe 1. Will be done. As the rinse water, tap water or the like can be used. The temperature of the rinse water is not particularly limited, but can be, for example, 5 ° C. or higher and 60 ° C. or lower. In FIG. 1, the shaded portion of the pipe 1 is the total capacity. When the rinse water is circulated, the sealing stopper 6 is closed.

<Example 1>
(1) Cleaning liquid As a cleaning liquid
(A) Sodium percarbonate 1000ppm
(B) Ascorbic acid 1000ppm
(C) Tartaric acid 1000ppm
A cleaning solution containing water (the balance is water, pH 4.1) was used.

(2) Biofilm removal test (piping model)
A test piece on which a biofilm was formed was immersed in a 6-well plate containing 5 mL of a cleaning solution or control (ultrapure water) and shaken at 40 ° C. and 60 rpm for a predetermined time (BioShaker BR-43FL manufactured by TAITEC). The shaking time is shown as the washing time in Table 1. Sodium carbonate was used to neutralize the washing liquid after shaking, and the pH was adjusted to 7. The pH of the present invention is a value measured by a pH meter using a glass electrode.
After leaving 1 mL of the cleaning solution and adding 2 mL of ultrapure water, it was rinsed once by shaking at 60 rpm for 5 minutes. This single rinse corresponds to rinsing with water in an amount of 1 times the total capacity of the pipe. In this test, 3/5 of the total capacity here corresponds to the total capacity of the piping, and 2/5 of the total capacity corresponds to the bathtub capacity. This was carried out using a piping model that assumes actual equipment that remains in the system.
After each rinse, the rinse water was discarded, and fresh ultrapure water was used to repeat the rinse up to the number shown in Table 1. The second and subsequent rinses were carried out by leaving 1 mL of rinse water and adding 2 mL of fresh ultrapure water to it. After a predetermined number of rinses, each test piece is immersed in a 0.1% crystal violet solution, stained with a biofilm, washed with ultrapure water to remove any excess crystal violet, and then washed with ultrapure water. The crystal violet dye that had been stained by binding to the biofilm of the test piece was extracted with 1 mL of ethanol, and the absorbance (OD570) was measured to determine the residual amount of the biofilm.
Based on the measured OD570, the biofilm removal rate was measured according to the following formula. The results are shown in Table 1.
Biofilm removal rate (%) = {(Control OD570-Blank OD570)-(Example OD570-Blank OD570)} x 100 / (Control OD570-Blank OD570)
The control is a crystal violet treatment without cleaning the test piece on which the biofilm is formed, and the blank refers to ethanol OD570.

<Example 2>
The biofilm removal test was carried out in the same manner as in Example 1, except that the treatment conditions were as shown in Table 2. In addition, the foaming inhibitory properties of the cleaning liquids shown in Table 2 were evaluated by the following methods. In addition, the reactivity with sodium hypochlorite (indicated as "reactivity with Na hypochlorite" in the table) of the rinse water for the final rinse performed in the biofilm removal test was determined by the following method. evaluated. The results are shown in Table 2.

* Evaluation of foaming inhibitory property 30 mL of cleaning solution was added to a 50 mL centrifuge tube, and the foam volume after vigorous shaking for 20 reciprocations was calculated from the scale of the centrifuge tube.
Foam volume (mL) = (scale at the top of the layer consisting of bubbles)-(scale at the boundary between the liquid part and the foam part)

* Evaluation of reactivity of rinse water with sodium hypochlorite To 1 mL of rinse water for the final rinse, an aqueous solution of sodium hypochlorite was added so as to be 2 ppm. The total chlorine concentration was measured by the DPD method, and if it was 1.9 ppm or more, it was judged that there was no reactivity with sodium hypochlorite, and it is indicated by ◯ in Table 2. When the concentration was less than 1.9 ppm, it was judged to be reactive, and is indicated by x in Table 2. That is, when there is no reactivity with sodium dichlorite (when it is expressed as 〇 as an evaluation), it indicates that rinsing is performed well.

<Example 3>
A biofilm removal test was performed in the same manner as in Example 2, but with the conditions as shown in Table 3. At that time, the state of precipitation of stains due to the presence or absence of neutralization after cleaning was visually observed. In the case of neutralization, sodium carbonate was added to the washing liquid after shaking to adjust the pH to 7. The results are shown in Table 3.

<Example 4 and Comparative Example 4>
A biofilm removal test was carried out in the same manner as in Example 1 using the cleaning solution having the composition shown in Table 4 under the conditions shown in Table 4. Moreover, about the cleaning liquid of Table 4, the foaming inhibitory property was evaluated by the same method as in Example 2. The results are shown in Table 4.

Claims (18)

After contacting the dirt adhering to the inside of the pipe with a cleaning liquid containing (a) a percarbonate, (b) a reducing agent and water for a predetermined time, the inside of the pipe is filled with water in an amount of at least twice the total capacity of the pipe. How to rinse and clean the pipes. The method for cleaning pipes according to claim 1, wherein the predetermined time is 10 minutes or more. The method for cleaning a pipe according to claim 1 or 2, wherein the pipe forms at least a part of a circulation path. The cleaning of the pipe according to any one of claims 1 to 3, wherein the pipe forms at least a part of the circulation path, the cleaning liquid is circulated and brought into contact with the pipe, and then the cleaning liquid is discharged from the pipe and then rinsed. Method. The method for cleaning pipes according to claim 3 or 4, wherein the circulation route includes a bathtub connected to the pipes. The method for cleaning a pipe according to any one of claims 1 to 5, wherein the rinsing is performed a plurality of times and the amount of water used for each rinsing is 1 times or more the total capacity of the pipe. (A) The method for cleaning a pipe according to any one of claims 1 to 6, wherein the component is sodium percarbonate. The method for cleaning a pipe according to any one of claims 1 to 7, wherein the concentration of the component (a) in the cleaning liquid is 100 ppm or more and 3000 ppm or less. (B) The method for cleaning a pipe according to any one of claims 1 to 8, wherein the component is ascorbic acid and a salt thereof, and one or more compounds selected from vitamin C. The method for cleaning a pipe according to any one of claims 1 to 9, wherein the concentration of the component (b) in the cleaning liquid is 100 ppm or more and 3000 ppm or less. The method for cleaning a pipe according to any one of claims 1 to 10, wherein the cleaning liquid further contains (c) one or more compounds selected from an organic acid and a salt thereof [hereinafter referred to as (c) component]. The method for cleaning a pipe according to claim 11, wherein the component (c) is one or more compounds selected from tartaric acid, succinic acid, malic acid and salts thereof. The method for cleaning a pipe according to claim 11 or 12, wherein the concentration of the component (c) in the cleaning liquid is 100 ppm or more and 3000 ppm or less. The method for cleaning a pipe according to any one of claims 1 to 13, wherein the pH of the cleaning liquid is 3 or more and 5 or less. The method for cleaning a pipe according to any one of claims 1 to 14, wherein the pH of the cleaning liquid after cleaning is adjusted to 5 or more and 9 or less, and then discharged from the pipe. The method for cleaning a pipe according to any one of claims 1 to 15, wherein the dirt contains a biofilm. A cleaning agent composition for piping, which contains (a) a percarbonate and (b) a reducing agent, and is used in the cleaning method according to any one of claims 1 to 16. (C) The cleaning agent composition for piping according to claim 17, further comprising (c) one or more compounds selected from an organic acid and a salt thereof.

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