JP2024011088A - Freezing prevention pipe and freezing prevention method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezing prevention pipe and a freezing prevention method, that are low cost and can prevent a water supply pipe from freezing even in an extremely low temperature environment.

SOLUTION: A freezing prevention pipe 1 comprises: a water supply pipe 2 made of resin; a cylindrical resin foamed body 3 that covers an outer peripheral surface of the water supply pipe 2; and an exterior pipe 4 made of resin that covers the outer peripheral surface of the resin foamed body 3, wherein a foaming ratio of the resin foamed body 3 is 20 to 50 times, the resin foamed body 3 is in close contact with the outer peripheral surface of the water supply pipe 2 and the inner peripheral surface of the exterior pipe 4 due to a press-fit structure, the resin foamed body 3 is a polystyrene foamed body, and the exterior pipe 4 is made of polyvinyl chloride.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to antifreeze pipes and antifreeze methods for preventing water pipes from freezing in cold regions.

Traditionally, iron pipes, which have excellent durability, have been widely used for water pipes. However, iron pipes tend to rust over long periods of use, so in recent years resin water pipes have become mainstream. While resin water pipes have the advantage of not rusting, they are less durable than iron pipes. Therefore, in cold regions, plastic water pipes may break if the tap water in the pipes freezes. In particular, resin water pipes installed above ground in homes and facilities are susceptible to the effects of outside temperature, so anti-freezing measures are important.

Known measures to prevent freezing include, for example, leaving a small amount of water out and wrapping a heating element around water pipes. Patent Document 1 describes a method of preventing freezing by wrapping a heating element, which is made up of a chip array in which a plurality of LED chips are lined up as a heat source and covering it with a covering material such as a soft plastic, around a water pipe. There is.

However, the above-mentioned measures require high water and electricity bills, and the cost of freezing prevention tends to be high. On the other hand, one low-cost measure is to cover the outer circumferential surface of water pipes with a heat insulating material such as styrofoam. For example, Patent Document 2 describes a heat-insulating plastic pipe in which a plastic pipe is coated with a foamed plastic layer and a protective metal layer is coated on top of the foamed plastic layer. Furthermore, Patent Document 3 describes a pipe with a heat insulating material in which the outer circumferential surface of a water pipe is covered with a heat insulating material and further covered with an exterior pipe made of resin.

Japanese Patent Application Publication No. 2014-148863 JP2002-295788A Japanese Patent Application Publication No. 2013-19506

By the way, in cold regions or mountainous regions, the outside temperature in winter may be well below 0°C (for example, -10°C or lower). It is desirable to have measures that can prevent water pipes from freezing even in such extremely low temperature environments. For example, in Patent Document 3, there is no study on the anti-freezing performance of the tube with heat insulating material described in the document.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an anti-freeze pipe and an anti-freeze method that are low-cost and can prevent water pipes from freezing even in an extremely low temperature environment. .

The antifreeze pipe of the present invention includes a water pipe made of resin, a cylindrical resin foam covering the outer peripheral surface of the water pipe, and a resin exterior pipe covering the outer peripheral surface of the resin foam, The resin foam is characterized in that the expansion ratio is 20 to 50 times.

The resin foam is characterized in that it is in close contact with the outer circumferential surface of the water pipe and the inner circumferential surface of the armored pipe due to a press-fit structure.

The amount of press-fitting of the resin foam into the water pipe is larger than the amount of press-fitting of the resin foam into the exterior pipe.

The antifreeze pipe is characterized in that an air layer is provided at least between the water pipe and the resin foam and between the resin foam and the exterior pipe.

The resin foam is a polystyrene foam, and the outer tube is made of polyvinyl chloride.

The method for preventing freezing of water pipes of the present invention is characterized in that water pipes are prevented from freezing using the antifreezing pipe of the present invention.

The antifreeze pipe of the present invention includes a water pipe made of resin, a cylindrical resin foam covering the outer peripheral surface of the water pipe, and a resin exterior pipe covering the outer peripheral surface of the resin foam, Since the foaming ratio of the resin foam is 20 to 50 times, the closed cells in the resin foam have an appropriate size, and the air inside the closed cells can effectively exert a heat insulation effect, and the outside temperature can be reduced. If it is extremely low, it can be dealt with by lowering the foaming ratio of the resin foam. Thereby, it is possible to prevent water pipes from freezing even in an extremely low temperature environment at low cost and as shown in the examples.

In one form, the resin foam is in close contact with the outer circumferential surface of the water pipe and the inner circumferential surface of the exterior pipe due to the press-fit structure, so the resin foam can be attached to the water pipe or the exterior pipe without using any other components. axial movement can be prevented. As a result, it is possible to prevent the generation of an axial gap due to the movement, and it becomes easier to prevent the water pipe from freezing.

As another form, in the antifreeze pipe, an air layer is provided between the water pipe and the resin foam, and between the resin foam and the exterior pipe, so the air layer provides insulation. The effectiveness can be increased, making it easier to prevent water pipes from freezing.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows one embodiment of the antifreeze tube of this invention. FIG. 2 is an enlarged sectional view of the antifreeze tube of FIG. 1; FIG. 3 is an enlarged sectional view of another embodiment of the antifreeze tube of the present invention. It is a figure showing an example of the freeze prevention method of the present invention. FIG. 2 is a diagram for explaining the structure of a test tube used in Examples.

FIG. 1 shows an embodiment of the antifreeze tube of the present invention. As shown in FIG. 1, the antifreeze pipe 1 includes a water pipe 2 made of resin, a resin foam 3 that covers the outer peripheral surface of the water pipe 2, and an exterior pipe 4 made of resin that covers the outer peripheral surface of the resin foam 3. and has. The resin foam 3 is not integrally molded with the water pipe 2 or the exterior pipe 4, and the antifreeze pipe 1 is a straight composite pipe made by combining three members.

In the antifreeze pipe 1, both ends of the water pipe 2 are configured to protrude from both end surfaces of the resin foam 3 and the exterior pipe 4. The protrusion 2a is inserted into, for example, an existing water pipe joint, and is used to fix the antifreeze pipe 1. Note that the protrusion 2a of the water pipe 2 can be omitted if necessary. For example, the axial length of the water pipe 2 may be made to be approximately the same as the axial lengths of the resin foam 3 and the exterior pipe 4.

As the water pipe 2, a commonly used water pipe made of resin can be used. As the resin constituting the water pipe, polyvinyl chloride, polyethylene, polybutene, crosslinked products of these, etc. can be used, and more specifically, impact-resistant hard vinyl chloride pipe (HIVP) and polyethylene for water supply are used. A double-layer pipe is used. Although the size and thickness of the water pipe 2 are not particularly limited, for example, the outer diameter φ ₁ (see FIG. 2) is about 10 mm to 400 mm, and the thickness is about 1 mm to 10 mm.

For example, many household water pipes are used in nominal size 13 (inner diameter 13 mm), nominal size 20 (inner diameter 20 mm), nominal size 25 (inner diameter 25 mm), and nominal size 40 (inner diameter 40 mm). In this case, the outer diameter _φ1 is about 18 mm to 48 mm, and the thickness is about 2 mm to 5 mm. Further, in the case of nominal sizes 13 to 25, the outer diameter _φ1 is 18 mm to 32 mm.

The resin foam 3 is a cylindrical member having a predetermined thickness in the radial direction, and the water pipe 2 is installed in the hole. In FIG. 1, the resin foam 3 is not divided into a plurality of parts on a plane including the central axis, but is made of a single member. The expansion ratio of the resin foam 3 is set to 20 to 50 times from the viewpoint of preventing freezing in an extremely low temperature environment. The resin foam 3 is formed by foam molding, and has a large number of closed cells partitioned by resin films inside. In the resin foam 3, heat (cold air) is transmitted by air convection within closed cells. By setting the expansion ratio within the above range, the closed cells have an appropriate size, and the air within the closed cells can effectively exhibit a heat insulating effect. On the other hand, when the magnification is high (for example, 60 times), adjacent closed cells tend to connect with each other due to the bulge and become large bubbles. As a result, heat conduction tends to become faster, and it is thought that the anti-freezing performance deteriorates, especially in extremely low temperature environments. The expansion ratio of the resin foam 3 is preferably 30 to 50 times, more preferably 35 to 45 times.

Further, by setting the expansion ratio of the resin foam 3 within the above range, the resin foam 3 can be given appropriate flexibility, which also leads to improvement in the ease of assembling the antifreeze tube. The resin foam 3 has lower rigidity than the water pipe 2 and the exterior pipe 4.

Although well-known methods can be applied to foam molding the resin foam 3, the foam bead method is preferred because it allows easy control of the expansion ratio after molding. An example of a foamed bead method using resin beads (expandable particles) as a raw material will be described below.

Resin beads (expandable particles) are obtained by impregnating a thermoplastic resin with an organic blowing agent by a well-known method. For example, polystyrene resin beads impregnated with an organic blowing agent can be obtained by stirring and polymerizing styrene monomer in water and adding an organic blowing agent thereto.

Thermoplastic resins include polystyrene resins; polyolefin resins such as polypropylene resins and polyethylene resins; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polylactic acid; polycarbonate resins; copolymers of these. Combination etc. can be used. Moreover, a plurality of resins can be used in combination as the thermoplastic resin. For example, a combination of polystyrene resin and polyolefin resin can be used.

Examples of organic blowing agents include aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, neopentane, and hexane, alicyclic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane, ethyl chloride, Examples include halogenated hydrocarbons such as methylene chloride, and dialkyl ethers such as dimethyl ether and diethyl ether.

The resin beads are foamed to form foamed particles. The foaming method is not particularly limited, and well-known methods can be employed, such as a method in which the organic foaming agent dissolved in the resin beads is expanded and foamed by heating with water vapor or the like (heat foaming). Then, by heating and fusing the obtained expanded particles in a cylindrical mold, a resin foam 3 of a desired size can be obtained.

Returning to FIG. 1, the exterior tube 4 is a resin tube, and the resin foam 3 is installed in the hole of the exterior tube 4. The exterior tube 4 has a role of protecting the resin foam 3 and is made of resin or the like having excellent weather resistance. As the resin, for example, polyvinyl chloride, polyethylene, polybutene, etc. can be used. Although the size and thickness of the exterior pipe 4 are not particularly limited, for example, the thickness is about 1 mm to 10 mm, and may be larger than the thickness of the water pipe 2.

In the antifreeze pipe 1, the resin constituting the water pipe 2 and the resin constituting the exterior pipe 4 may be different types of resins or may be the same type of resin. For example, polyvinyl chloride pipes can be used as the water pipe 2 and the exterior pipe 4.

FIG. 2 shows a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, in this form, the resin foam 3 is in close contact with the outer peripheral surface of the water pipe 2 and the inner peripheral surface of the exterior pipe 4. For example, the resin foam 3 has an allowance for press-fitting into the water pipe 2 and an allowance for press-fitting into the exterior pipe 4 before installation. In this case, the resin foam 3 is in close contact with the outer circumferential surface of the water pipe 2 and the inner circumferential surface of the exterior pipe 4 due to the press-fit structure. The resin foam 3 is softer than the water pipe 2 and the exterior pipe 4, and for example, the water pipe 2 and the exterior pipe 4 are press-fitted into the resin foam 3, respectively.

This press-fit structure prevents the water pipe 2 from moving in the axial direction and the exterior pipe 4 from moving in the axial direction with respect to the resin foam 3 without using other members such as seals or adhesives. Can be done. As a result, it is possible to prevent the generation of an axial gap due to the movement, and it becomes easier to prevent the water pipe 2 from freezing.

Here, assuming that the inner diameter of the resin foam 3 before being attached to the antifreeze pipe 1 is φ ₃ and the outer diameter is φ ₄ , the press-fitting allowance A of the resin foam 3 into the water pipe 2 is (φ ₁ − φ ₃ ). The press-fitting allowance A is, for example, 1 mm to 10 mm. Further, the press-fitting allowance B of the resin foam 3 into the exterior tube 4 is expressed as (φ ₄ −φ ₂ ). The press-fitting allowance B is, for example, 1 mm to 10 mm. For example, the press-fitting allowance A may be larger than the press-fitting allowance B. In this case, the adhesiveness of the resin foam 3 to the water pipe 2 can be further improved.

Note that the form in which the resin foam 3 is brought into close contact with the outer circumferential surface of the water pipe 2 and the inner circumferential surface of the exterior pipe 4 is not limited to a press-fit structure. For example, the outer diameter φ ₁ of the water pipe 2 and the inner diameter φ ₃ of the resin foam 3 may be made the same, and the water pipe 2 may be inserted into the resin foam 3. The resin foam 3 may be inserted into the outer tube 4 by making φ ₄ and the inner diameter φ ₂ of the outer tube 4 the same.

Next, FIG. 3 shows an enlarged sectional view of another embodiment of the antifreeze tube of the present invention. In this form, an air layer 5 is provided between the water pipe 2 and the resin foam 3, and an air layer 6 is provided between the resin foam 3 and the exterior pipe 4 in the antifreeze pipe 1'. . Since the air layers 5 and 6 also function as a heat insulating layer, they work effectively to prevent freezing.

In this form, the dimensions of the resin foam 3 do not change before and after mounting. In FIG. 3, the dimensional difference A between the outer diameter φ ₁ of the water pipe 2 and the inner diameter φ ₃ of the resin foam 3 is expressed as (φ ₃ −φ ₁ ). The dimensional difference A is, for example, 1 mm to 10 mm. Further, the dimensional difference B between the outer diameter φ ₄ of the resin foam 3 and the inner diameter φ ₂ of the outer tube 4 is expressed as (φ ₂ −φ ₄ ). The dimensional difference B is, for example, 1 mm to 10 mm. For example, the dimensional difference A can be made larger than the dimensional difference B. That is, in this case, the thickness of the air layer 5 is made larger than the thickness of the air layer 6.

The radial thickness t of the resin foam 3 is, for example, 10 mm to 50 mm. The thickness t is preferably larger than the thickness of the water pipe 2 and the thickness of the exterior pipe 4. In relation to the thickness of the water pipe 2, the thickness t is, for example, 2 to 10 times the thickness of the water pipe 2, and may be 2 to 5 times the thickness of the water pipe 2.

As described above, FIG. 2 shows a form in which the resin foam 3 is in close contact with the water pipe 2 and the exterior pipe 4, and in FIG. 3 has been shown in which it is attached with a gap, but these forms may be combined as appropriate. For example, while the resin foam 3 is in close contact with the water pipe 2 by a press-fit structure, the resin foam 3 may be attached to the exterior pipe 4 so as to form an air layer 6 therebetween. In this case, it is possible to prevent the water pipe 2 from moving in the axial direction with respect to the resin foam 3, and to obtain a heat insulating effect due to the air layer 6.

FIG. 4 shows an outline of the freezing prevention method of the present invention. This method is a method for preventing water pipes from freezing using the antifreeze pipe of the present invention. Specifically, as shown in FIG. 4, this is done by replacing an existing water pipe (for example, a water pipe laid above the ground and exposed to the outside air) with an antifreeze pipe 1. The length of the antifreeze pipe 1 is changed as appropriate depending on the length of the existing water pipe and the installation position. With such a method, it is possible to easily take measures to prevent water pipes from freezing. Furthermore, weather resistance and appearance can be further improved by utilizing vertical gutters.

The antifreeze tube of the present invention is not limited to the configurations shown in FIGS. 1 to 4 above. For example, the resin foam may be divided into a plurality of parts (for example, two parts) along a plane including the central axis. In the case of splitting into two, a cylindrical resin foam can be obtained by combining two arcuate members. Further, a gap may be provided in a part of the outer tube in the circumferential direction. With this configuration, by widening the joint, the resin foam can be assembled from the outside. After assembly, a fixture or the like may be used to secure the abutment in a closed state. By configuring the resin foam and the exterior pipe in this way, it is possible to take measures to prevent existing water pipes from freezing, for example, without replacing the existing water pipes.

Example 1, Comparative Example 1
A polyvinyl chloride pipe with a nominal size of 20 (inner diameter 20 mm, outer diameter φ ₁ 26 mm, thickness 3 mm) was prepared as a water pipe.
A polystyrene foam was prepared as the resin foam. The expansion ratio of the polystyrene foam used was 40 times in Example 1 and 60 times in Comparative Example 1.
A polyvinyl chloride pipe was prepared as an exterior pipe.

Using each of the prepared members, a test tube was produced as shown in FIG. 5. First, a water pipe was press-fitted into the hole of the resin foam (FIG. 5(a)). Then, one side of the protrusions on both sides of the water pipe was covered with a cap formed with the same expansion ratio as the resin foam. Thereafter, water was poured into the water pipe, and the other side of the protrusion was covered with a cap to obtain a cylindrical body (FIG. 5(b)). Next, this cylindrical body was press-fitted into the hole of the outer tube (Fig. 5(c)), and finally, both ends were covered with caps made of the same material as the outer tube to obtain a test tube ( Figure 5(d)).

In the test tubes of Example 1 and Comparative Example 1, the resin foam was in close contact with the water pipe and the exterior pipe without any gaps.

The test tubes of Example 1 and Comparative Example 1 were placed in a freezer and allowed to stand at -15°C for 10 hours. Thereafter, the test tube was taken out of the freezer and the condition of the water inside the water pipe and the condition of the water pipe was confirmed.

As a result, in Comparative Example 1, which used a resin foam with an expansion ratio of 60 times, the water inside was frozen, whereas in Example 1, which used a resin foam with an expansion ratio of 40 times, The water inside was not frozen, and the water pipes were in good condition.

The antifreeze pipe of the present invention is low cost and can prevent water pipes from freezing even in extremely low temperature environments, so it is useful as an antifreeze measure in cold regions.

1, 1' Antifreeze pipe 2 Water pipe 3 Resin foam 4 Exterior pipe 5 Air layer 6 Air layer

Claims (6)

It has a water pipe made of resin, a cylindrical resin foam covering the outer peripheral surface of the water pipe, and an exterior pipe made of resin covering the outer peripheral surface of the resin foam, and the foaming ratio of the resin foam is An antifreeze tube characterized by being 20 to 50 times more durable. 2. The antifreeze pipe according to claim 1, wherein the resin foam is in close contact with the outer peripheral surface of the water pipe and the inner peripheral surface of the exterior pipe by a press-fit structure. 3. The antifreeze pipe according to claim 2, wherein the amount of press-fitting of the resin foam into the water pipe is larger than the amount of press-fitting of the resin foam into the exterior pipe. Claim characterized in that, in the antifreeze pipe, an air layer is provided between at least one of the water pipe and the resin foam and between the resin foam and the exterior pipe. 1. The antifreeze tube according to 1. 3. The antifreeze tube according to claim 1, wherein the resin foam is a polystyrene foam, and the outer tube is made of polyvinyl chloride. A method for preventing freezing, comprising preventing the water pipe from freezing using the antifreeze pipe according to claim 1 or 2.

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