JP2010078194A - Method and device for cleaning refrigerant pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for cleaning a refrigerant pipe securely and easily cleaning the refrigerant pipe when an old refrigerant is replaced with a new refrigerant in a separate type air conditioner using the old refrigerant. <P>SOLUTION: In this method and device for cleaning the refrigerant pipe, by removing an outdoor unit and an indoor unit, a cleaning pipe line for the refrigerant pipe is formed. By decompressing inside of a storage cylinder, the new refrigerant is sucked. Nitrogen gas is pressed inside the storage cylinder and mixed fluid with the new refrigerant is produced. The mixed fluid is pressed into the cleaning pipe line, and inside of the refrigerant piping is cleaned. After the cleaning, the old refrigerant, mineral oil and the new refrigerant are collected to a refrigerant collecting cylinder, and then, the nitrogen gas is sent out to the cleaning pipe line to clean inside of the refrigerant pipe. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for cleaning a refrigerant pipe when a separate air conditioner using an old refrigerant is replaced with a new refrigerant.

  Conventionally, a fluorocarbon refrigerant containing chlorine called a so-called old refrigerant such as a CFC type or HCFC type has been used as a refrigerant of a separate type air conditioner. It is necessary to replace with a separate air conditioner compatible with a new HFC-based refrigerant that does not contain chlorine, which is called a new refrigerant. In this case, it is difficult to replace the refrigerant pipe connecting the indoor unit and the outdoor unit of the separate type air conditioner when the length of the pipe is long, or when it is buried in the wall surface or the ceiling. Even if it can be replaced, it is advantageous to reuse existing refrigerant piping for economic reasons. When replacing old refrigerant equipment with new refrigerant equipment, clean the existing refrigerant piping. Then, processing is performed and reused so as to obtain the same function as that of the newly installed refrigerant pipe.

As such a refrigerant pipe cleaning method and cleaning apparatus, there is one disclosed in JP-A-2005-188825. According to the present invention, "the old refrigerant machine is replaced with a new refrigerant machine with an air-cooled separate type air conditioner, so that residual oil and dust in the existing pipe can be reliably and efficiently removed when washing the existing refrigerant pipe after collecting the refrigerant. The process of connecting a cleaning device having means for mixing and dissolving nitrogen gas into the cleaning liquid and flowing into the piping instead of the old outdoor unit, and replacing the old indoor unit with Connecting the connecting pipe to the existing pipe, pressurizing the cleaning liquid from the cleaning device into the existing pipe and flowing it in one direction to sequentially clean and wash the inside of the pipe, and from the cleaning device to the existing pipe in the opposite direction. A process of cleaning and cleaning the inside of the pipe in order by pressurizing and flowing the cleaning liquid, a process of removing foreign matters remaining in the existing pipe, and a nitrogen gas from a nitrogen gas cylinder under pressure into the existing pipe, And sampling collected by. "How to clean the existing pipe through the step of simultaneously discharging the foreign material in the tube is obtained by a means for solving the above-described problem.
JP 2005-188825 A

  However, in the cleaning method disclosed in Japanese Patent Application Laid-Open No. 2005-188825, the cleaning liquid is pressurized from the cleaning device to the existing piping and is allowed to flow in one direction to sequentially clean and clean the inside of the pipe, and then the cleaning device returns to the existing piping again. In other words, the cleaning liquid is pressurized and flown in the opposite direction to sequentially clean and wash the inside of the pipe, and then nitrogen gas is pressurized and flowed into the existing piping, and the washing process must be complicated. In addition, “the cleaning device is configured to include each member such as a cleaning liquid tank, a pump, a nitrogen gas cylinder, a recovery tank, a recovery can, a spare tank, a tray, etc. These components are connected to each other by piping. In the state, it is stored on the carriage and can be used by carrying it to an appropriate place as one unit ”(described in paragraph [0024]).“ The cleaning liquid tank is a stainless steel tank with a lid of an appropriate capacity. Yes, as shown in the figure, the lid is provided with a mesh part in which through holes are arranged by punching, and a moisture removal filter made of activated carbon and silica gel is installed on the upper surface of the mesh part. '' As described in paragraph [0025], the structure of the cleaning liquid tank is complicated, and the cleaning apparatus itself is relatively large.

  Accordingly, the present invention provides a refrigerant pipe cleaning method and a cleaning apparatus capable of reliably and easily cleaning refrigerant pipes when replacing a separate air conditioner using an old refrigerant with a new refrigerant. For the purpose.

  In order to achieve the above object, the present inventor has earnestly studied, and as a result, obtained a knowledge that a new refrigerant and nitrogen gas can be used as a cleaning liquid by using a mixed fluid by a predetermined method. The present invention is based on this finding.

That is, in order to achieve the above-described object, the refrigerant pipe cleaning method according to claim 1 of the present application is a refrigerant for converting a separate air conditioner composed of an outdoor unit and an indoor unit from an old refrigerant device to a new refrigerant device. A method of removing and cleaning refrigerant and residual oil in a pipe, wherein an inlet pipe and a discharge pipe are connected to both ends of the refrigerant pipe from which one of the outdoor unit or the indoor unit is removed, and the outdoor unit or A connecting pipe that connects both ends of the refrigerant pipe from which the other end of the indoor unit is removed is connected, the other end of the injection pipe is connected to a storage cylinder, and the other end of the discharge pipe is connected to a refrigerant recovery cylinder. The storage cylinder is depressurized to a state close to absolute vacuum, the new refrigerant is sucked from a new refrigerant tank that stores new refrigerant, and the new cold is discharged from a nitrogen gas tank that stores nitrogen gas in the storage cylinder. Nitrogen gas having a predetermined volume ratio is flown into the mixed fluid of the new refrigerant and the nitrogen gas, and the storage cylinder is pressurized to a predetermined pressure by the nitrogen gas and the mixed fluid is injected. The refrigerant is injected into the refrigerant pipe through the pipe, the old refrigerant and the mixed fluid in the refrigerant pipe are collected into the refrigerant collection cylinder through the discharge pipe, and then nitrogen gas is supplied from the nitrogen gas tank to a predetermined amount. It is characterized by being injected into the refrigerant pipe at a stretch under pressure.
The “state close to absolute vacuum” refers to a state where the value when measured with a pressure gauge in MPa with the first decimal place as a significant figure is “0.0”. “At once” means, for example, that the installed on-off valve is “closed” and nitrogen gas is brought to a predetermined pressure, and then the on-off valve is instantly opened and nitrogen gas is injected into the refrigerant pipe. Say.
Moreover, the cleaning method of the refrigerant pipe according to claim 2 of the present application is the cleaning method of the refrigerant pipe according to claim 1, wherein the predetermined volume ratio under 1 atm is substantially less nitrogen gas than the new refrigerant 1. It is characterized by being 14-23.
The refrigerant pipe cleaning method according to claim 3 of the present application is the refrigerant pipe cleaning method according to claim 1 or 2, wherein the predetermined pressure at which the inside of the storage cylinder is pressurized is approximately 0. The predetermined pressure at which nitrogen gas is injected into the refrigerant pipe from the nitrogen gas tank at once is approximately 0.2 MPa to 0.3 MPa.
Furthermore, the refrigerant pipe cleaning method according to claim 4 of the present application is the refrigerant pipe cleaning method according to any one of claims 1 to 3, wherein the nitrogen gas is blown at a time under a predetermined pressure. In the step of being injected into the inside, the nitrogen gas tank is directly connected to the injection pipe.
In addition, the refrigerant pipe cleaning device according to claim 5 of the present application removes and cleans the refrigerant in the refrigerant pipe at the time of conversion from the old refrigerant device to the new refrigerant device of the separate air conditioner composed of the outdoor unit and the indoor unit. A refrigerant pipe cleaning apparatus, comprising a cylindrical storage cylinder connected via an injection pipe to one end of the refrigerant pipe from which one of the outdoor unit or the indoor unit is removed, and a switching valve connected to the storage cylinder A vacuum pump connected to the storage cylinder, a new refrigerant tank connected to the storage cylinder via a switching valve, a nitrogen gas cylinder connected to each of the storage cylinder and the injection pipe via a switching valve, and the outdoor unit Or a connecting pipe that connects both ends of the refrigerant pipe from which the other of the indoor unit is removed, and a discharge pipe to the other end of the refrigerant pipe from which one of the outdoor unit or the indoor unit is removed. A refrigerant recovery cylinder which is continued, made, said injection tube and said switching to drain valve is interposed, it is characterized in that.
The refrigerant pipe cleaning apparatus according to claim 6 of the present application is the refrigerant pipe cleaning apparatus according to claim 5, wherein the switching valve connected to the vacuum pump and the switching valve connected to the new refrigerant tank are one first A two-way switching valve, wherein a second two-way switching valve is interposed between the first two-way switching valve and the storage cylinder, and the nitrogen gas cylinder is placed in the second two-way switching valve. It is connected.
Further, the refrigerant pipe cleaning device according to claim 7 of the present application is the refrigerant pipe cleaning device according to claim 5 or claim 6, and the switching valve interposed in the injection pipe is a third two-way switching valve. The nitrogen gas cylinder is connected to the third two-way switching valve.

The present invention has the following effects by the above configuration.
(1) The storage cylinder is depressurized to suck in the new refrigerant, and then nitrogen gas is introduced to pressurize, so in the storage cylinder, the new refrigerant and fine bubbles of nitrogen gas are mixed evenly. Is made instantly.
The pressurized mixed fluid is injected into the refrigerant pipe all at once, and the mixed fluid is composed of new refrigerant and pressurized nitrogen gas in fine bubbles. A shock wave is generated when the pipe touches the wall surface of the pipe, decompresses, expands and repels, and the mineral oil adhering to the refrigerant pipe is peeled off. As a result, the old refrigerant in the refrigerant pipe is pushed out by the mixed fluid, and the mineral oil adhering to the refrigerant pipe is also pushed out.
(2) In the cleaning method of the present invention, since the mixed fluid of the new refrigerant and nitrogen gas is allowed to flow into the refrigerant pipe and then only the nitrogen gas is allowed to flow at once, the refrigerant pipe can be cleaned. The number of the refrigerant pipes is small and can be easily cleaned.
(3) Further, since a mixed fluid of new refrigerant and nitrogen gas is used as the cleaning liquid, even if the cleaning liquid remains in the refrigerant pipe, impurities may be generated due to the mixing of the old new refrigerant and the new refrigerant. In addition, since only nitrogen gas is allowed to flow in in the final process, no harmful residue remains in the cleaned refrigerant pipe.
(4) According to the applicant's knowledge, the volume of nitrogen gas at 1 atm with respect to the new refrigerant volume 1 is approximately 14 to 23, and the pressure in the storage cylinder is approximately 0.2 MPa to 0.3 MPa. As a result, the new refrigerant and the nitrogen gas in fine bubbles can be mixed evenly and instantaneously, and the repelling effect of the pressurized fine bubbles is increased, and the synergistic effect of the fluidity and detergency of the mixed fluid Is the maximum.
Further, the predetermined pressure for injecting nitrogen gas into the refrigerant pipe at a stroke is set to approximately 0.2 MPa to 0.3 MPa, and by injecting into the refrigerant pipe at once, the force with which the nitrogen gas in the refrigerant pipe blows away the residue is maximized. Become.
(5) In the step of injecting nitrogen gas into the refrigerant pipe at a time under a predetermined pressure, the nitrogen gas is directly injected into the refrigerant pipe by directly connecting the nitrogen gas tank to the injection pipe. Gas pressure loss is reduced.
(6) The main components of the refrigerant pipe cleaning device are a separate storage cylinder, a vacuum pump, a new refrigerant tank, a nitrogen gas cylinder, and a refrigerant recovery cylinder, and pipes and refrigerant pipes connecting the main components as accessory parts The storage cylinder is a pressure-resistant cylinder whose both ends are closed. Therefore, the refrigerant pipe cleaning device is extremely simple in configuration, and therefore is easy to maintain and manage, and is excellent in workability, transportability and economy.
(7) A second two-way switching valve is interposed between the storage cylinder and the new refrigerant tank and between the vacuum pump and the new refrigerant tank between the first two-way switching valve and the storage cylinder. When a third two-way switching valve is installed in the injection pipe,
(A) Unless the first two-way switching valve is switched, it is possible to prevent a malfunction in which nitrogen gas flows before the inside of the storage cylinder is depressurized.
(B) Unless the second two-way switching valve is switched, it is possible to prevent a malfunction that nitrogen gas flows before the new refrigerant flows into the storage cylinder.
(C) Unless the third two-way switching valve is switched, it is possible to prevent a malfunction in which nitrogen gas flows before the mixed fluid of the new refrigerant and nitrogen gas finishes flowing into the refrigerant pipe.

Hereinafter, an embodiment according to the best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of the refrigerant pipe cleaning device according to the embodiment, and FIG. 2 is a flowchart of the refrigerant pipe cleaning method according to the embodiment.
In FIG. 1, reference numeral 1 is a refrigerant pipe cleaning apparatus according to the embodiment, reference numeral 11 is a storage cylinder, reference numeral 13 is a vacuum pump, reference numeral 15 is a new refrigerant tank, reference numeral 17 is a nitrogen gas cylinder, reference numeral 19 is a refrigerant recovery cylinder, Reference numeral 31 is an injection pipe, reference numeral 33 is a connection pipe, reference numeral 35 is a discharge pipe, reference numeral 41 is a vacuum pump connection pipe, reference numeral 43 is a new refrigerant tank connection pipe, reference numeral 45 is a nitrogen gas cylinder connection pipe, reference numeral 51 is the first 2 Direction switching valve, reference numeral 52 is a second two-way switching valve, reference numeral 53 is a third two-way switching valve, reference numeral 55 is an exhaust switching valve, reference numeral 57 is a recovery switching valve, reference numeral 59 is a gas escape pipe, reference numeral 61 is Refrigerant piping, 63 is an outdoor unit, and 65 is an indoor unit.

  First, the structure of the refrigerant | coolant piping cleaning apparatus 1 which concerns on an Example is demonstrated based on FIG.

  The refrigerant pipe cleaning device 1 mainly includes a cylindrical storage cylinder 11 whose both ends are closed, a vacuum pump 13, a new refrigerant tank 15 that stores new refrigerant, a nitrogen gas cylinder 17 that stores nitrogen gas, The refrigerant recovery cylinder 19 and a connecting pipe that detachably connects the above-described components are configured. That is, the storage cylinder 11 and the vacuum pump 13 are detachably connected by a vacuum pump connection pipe 41, and the storage cylinder 11 and the new refrigerant tank 15 are detachably connected by a new refrigerant tank connection pipe 43, The nitrogen gas cylinder 17 is detachably connected by a nitrogen gas cylinder connection pipe 45, and the storage cylinder 11 and the refrigerant recovery cylinder 19 are detachably connected via an injection pipe 31, a refrigerant pipe 61, a connection pipe 33 and a discharge pipe 35. ing. Further, the nitrogen gas cylinder connection pipe 45 is branched from the middle, and the tip thereof is connected to the injection pipe 31.

A switching valve is interposed in the vacuum pump connection pipe 41, the new refrigerant tank connection pipe 43, and the nitrogen gas cylinder connection pipe 45. That is, the vacuum pump connection pipe 41 and the new refrigerant tank connection pipe 43 are provided with a first two-way switching valve 51, and the vacuum pump connection pipe 41 and the new refrigerant tank are interposed via the first two-way switching valve 51. The connecting pipe 43 is joined, and the joined connecting pipe extends in the direction of the storage cylinder 11 and is connected to the storage cylinder 11 via the second two-way switching valve 52. A nitrogen gas cylinder connection pipe 45 is connected to the second two-way switching valve 52.
The injection pipe 31 is provided with a third two-way switching valve 53, and the tip of the branch pipe branched from the nitrogen gas cylinder connection pipe 45 is connected to the third two-way switching valve 53 as described above. ing.
Further, the discharge pipe 35 is bifurcated in the direction of the refrigerant recovery cylinder 19, one of which is connected to the refrigerant recovery cylinder 19 via the recovery switching valve 57 and the other is connected to the exhaust switching valve 55. The tip of the lever is open. The exhaust switching valve 55 and the recovery switching valve 57 may be combined into a single two-way switching valve.

The tip of the injection pipe 31 is connected to one end of the refrigerant pipe 61 removed from the indoor unit 65, and the other end of the refrigerant pipe 61 removed from the indoor unit 65 is connected to the discharge pipe 35. Then, both ends of the refrigerant pipe 61 removed from the outdoor unit 63 are connected by the connecting pipe 33 to form a bypass pipe line including the refrigerant pipe 61 → the connecting pipe 33 → the refrigerant pipe 61.
The injection pipe 31 and the discharge pipe 35 are connected to the refrigerant pipe 61 removed from the indoor unit 65, and the connecting pipe 33 is connected to the refrigerant pipe 61 removed from the outdoor unit 63. Of course, the machine 63 may be replaced.

  As described above, the exhaust pipe 35 is connected to the refrigerant recovery cylinder 19 via the exhaust switching valve 55. However, in addition to the exhaust pipe 35, a gas escape pipe 59 is connected and its tip is opened to the outside. Has been.

  Next, a refrigerant pipe cleaning method using the refrigerant pipe cleaning apparatus 1 according to the embodiment will be described in order based on FIG. 1 and FIG.

An example of the procedure for cleaning the refrigerant piping is as follows:
(1) First, the old refrigerant in the outdoor unit 63, the indoor unit 65, and the refrigerant pipe 61 is recovered by pumping down (step 1). In addition, when the pump of a separate type air conditioner does not operate, step 1 is skipped and it starts from step 2.

(2) After collecting the old refrigerant by pumping down, the refrigerant pipe 61 is removed from the indoor unit 65, the injection pipe 31 is connected to one end thereof, the discharge pipe 35 is connected to the other end, and the refrigerant pipe 61 is connected to the outdoor unit 63. The connecting pipe 33 is connected to both ends thereof (step 2).

(3) The first two-way switching valve 51 and the second two-way switching valve 52 are operated to connect the vacuum pump 13 and the storage cylinder 11 and the third two-way switching valve 53 is operated. Then, the discharge port of the storage cylinder 11 is closed. And the vacuum pump 13 is operated and the inside of the storage cylinder 11 is pressure-reduced to the state close | similar to absolute vacuum (step 3).

(4) When the first two-way switching valve 51 is operated to cause the new refrigerant tank 15 and the storage cylinder 11 to communicate with each other, new refrigerant is sucked into the decompressed storage cylinder 11 from the new refrigerant tank 15. (Step 4). The amount of the new refrigerant sucked depends on the length of the existing refrigerant pipe 61, but is approximately 500 g to 800 g for a domestic separate air conditioner, and approximately 1 kg to 2 kg for a commercial separate air conditioner. It is.
In the examples, HFC-365mfc (hydrofluorocarbon-365mfc) is used as the new refrigerant. The connection between the vacuum pump 13 and the storage cylinder 11 is interrupted by the operation of the first two-way switching valve 51.

(5) When the second two-way switching valve 52 is operated to connect the nitrogen gas cylinder 17 and the storage cylinder 11, a predetermined amount of nitrogen gas pressurized from the nitrogen gas cylinder 17 flows into the storage cylinder 11. (Step 5). By this process, in the storage cylinder 11, a mixed fluid in which new refrigerant and fine bubble nitrogen gas are evenly mixed is instantly created.
In addition, it is preferable that the amount of nitrogen gas in the case of a home-use separate type air conditioner is approximately 9,000 cm ³ under 1 atm. Further, the operation of the second two-way switching valve 52 cuts off the connection between the vacuum pump 13 and the new refrigerant tank 15 and the storage cylinder 11.

(6) With the nitrogen gas cylinder 17 and the storage cylinder 11 connected, the third two-way switching valve 53 and the recovery switching valve 57 are operated to store the storage cylinder 11 → the injection pipe 31 → the third two-way switching valve 53. When the pipe for cleaning the refrigerant pipe composed of the injection pipe 31 → the refrigerant pipe 61 → the connection pipe 33 → the refrigerant pipe 61 → the discharge pipe 35 → the recovery switching valve 57 → the discharge pipe 35 → the refrigerant recovery cylinder 19 is opened, The mixed fluid of the new refrigerant and nitrogen gas flows into the cleaning conduit while being pressurized by the nitrogen gas, and is recovered in the refrigerant recovery cylinder 19 so as to be pushed out by the nitrogen gas (step 6). .
While the mixed fluid of the new refrigerant and nitrogen gas flows through the cleaning pipe, the fine bubbles of nitrogen gas bounce against the wall surface of the refrigerant pipe, and the mineral oil adhering to the refrigerant pipe 61 peels off. The mineral oil that has been dropped and adhered to the refrigerant pipe 61 together with the mixed fluid is also recovered in the refrigerant recovery cylinder 19. In this step, gaseous nitrogen gas is released out of the refrigerant recovery cylinder 19 by the gas escape pipe 59, and only the old refrigerant, new refrigerant and mineral oil are stored in the refrigerant recovery cylinder 19.
In the case of a defective compressor of a separate type air conditioner, the oil contained in the old refrigerant is often burnt. Therefore, in Step 6, approximately half of the mixed fluid is first injected into the refrigerant pipe 61. Then, the degree of contamination may be confirmed, and then the remaining substantially half amount may be injected into the refrigerant pipe 61 to clean the inside.

(7) The second two-way switching valve 52, the third two-way switching valve 53, the exhaust gas switching valve 55, and the recovery switching valve 57 are operated, and the nitrogen gas cylinder 17 → the nitrogen gas cylinder connection pipe 45 → the third two directions. A line for finishing cleaning of the refrigerant pipe composed of the switching valve 53 → the injection pipe 31 → the refrigerant pipe 61 → the connection pipe 33 → the refrigerant pipe 61 → the discharge pipe 35 → the exhaust gas switching valve 55 is opened. Then, after the nitrogen gas is introduced from the nitrogen gas cylinder 17 to a predetermined pressure with the third two-way switching valve 53 set to “closed”, the third two-way switching valve 53 is “fully opened” at once. The pressurized nitrogen gas flows into the finish cleaning pipe and is discharged to the outside through the exhaust switching valve 55 (step 7).
In addition, this process is repeated about 2-4 times as needed. Further, the operation of the second two-way switching valve 52 and the third two-way switching valve 53 disconnects the connection between the nitrogen gas cylinder 17 and the storage cylinder 11.
By the above procedure, the inside of the refrigerant pipe is cleaned.

FIG. 1 is a configuration diagram of a refrigerant pipe cleaning device according to an embodiment. FIG. 2 is a flowchart of the cleaning method for the refrigerant pipe according to the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drain pipe washing | cleaning apparatus which concerns on Example 11 Storage cylinder 13 Vacuum pump 15 New refrigerant tank 17 Nitrogen gas cylinder 19 Refrigerant recovery cylinder 31 Injection pipe 33 Connection pipe 35 Discharge pipe 51 First two-way switching valve 52 Second two-way switching Valve 53 Third two-way switching valve 57 Recovery switching valve 61 Refrigerant piping 63 Outdoor unit 65 Indoor unit

Claims (7)

A method for removing and cleaning refrigerant and residual oil in a refrigerant pipe when converting a separate air conditioner composed of an outdoor unit and an indoor unit from an old refrigerant device to a new refrigerant device,
An injection pipe and a discharge pipe are connected to both ends of the refrigerant pipe from which one of the outdoor unit or the indoor unit is removed, and both ends of the refrigerant pipe from which the other of the outdoor unit or the indoor unit is removed are connected. Connecting pipe is connected,
The other end of the injection pipe is connected to a storage cylinder and the other end of the discharge pipe is connected to a refrigerant recovery cylinder.
In the storage cylinder, the new refrigerant is sucked from a new refrigerant tank that is depressurized to a state close to absolute vacuum and stores the new refrigerant,
A nitrogen gas having a predetermined volume ratio to the new refrigerant is introduced from a nitrogen gas tank that stores the nitrogen gas in the storage cylinder to form a mixed fluid of the new refrigerant and the nitrogen gas;
The storage cylinder is pressurized to a predetermined pressure by the nitrogen gas, the mixed fluid is injected into the refrigerant pipe through the injection pipe, and the old refrigerant and the mixed fluid in the refrigerant pipe are discharged into the discharge pipe. Is recovered in the refrigerant recovery cylinder through
Thereafter, nitrogen gas is injected into the refrigerant pipe from the nitrogen gas tank at a stretch under a predetermined pressure.   The method for cleaning refrigerant piping according to claim 1, wherein the predetermined volume ratio under 1 atm is about 14 to 23 of nitrogen gas relative to the new refrigerant 1. The predetermined pressure at which the inside of the storage cylinder is pressurized is approximately 0.2 MPa to 0.3 MPa,
3. The refrigerant pipe cleaning according to claim 1, wherein a predetermined pressure at which nitrogen gas is injected into the refrigerant pipe from the nitrogen gas tank at a stroke is approximately 0.2 MPa to 0.3 MPa. 4. Method.   4. The nitrogen gas tank is directly connected to the injection pipe in the step of injecting the nitrogen gas into the refrigerant pipe at a time under a predetermined pressure. 5. The refrigerant piping cleaning method described. A refrigerant pipe cleaning device that removes and cleans refrigerant in the refrigerant pipe at the time of conversion from an old refrigerant device to a new refrigerant device of a separate type air conditioner composed of an outdoor unit and an indoor unit,
A cylindrical storage cylinder connected via an injection pipe to one end of the refrigerant pipe from which one of the outdoor unit or the indoor unit is removed;
A vacuum pump connected to the storage cylinder via a switching valve;
A new refrigerant tank connected to the storage cylinder via a switching valve;
A nitrogen gas cylinder connected to each of the storage cylinder and the injection pipe via a switching valve;
A connecting pipe that connects both ends of the refrigerant pipe from which the other of the outdoor unit or the indoor unit is removed;
A refrigerant recovery cylinder connected via a discharge pipe to the other end of the refrigerant pipe from which one of the outdoor unit or the indoor unit is removed,
A refrigerant pipe cleaning apparatus, wherein a switching valve is interposed in the injection pipe and the discharge pipe.   The switching valve connected to the vacuum pump and the switching valve connected to the new refrigerant tank are one first two-way switching valve, and a second valve is provided between the first two-way switching valve and the storage cylinder. The refrigerant pipe cleaning apparatus according to claim 5, wherein the two-way switching valve is interposed, and the nitrogen gas cylinder is connected to the second two-way switching valve.   The switching valve interposed in the injection pipe is a third two-way switching valve, and the nitrogen gas cylinder is connected to the third two-way switching valve. Item 7. The refrigerant pipe cleaning device according to Item 6.

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