JPH0591977A - Washing and disinfection system for endoscope - Google Patents

Abstract

PURPOSE:To prevent a disinfectant soln. from dilution, even when the number of repeating of washing and disinfection work for an endoscope is increased, by positioning the confluence of a channel-connecting pipe path and disinfectant soln. pipe path for feeding the disinfectant soln. on the downstream side of the confluence of the channel-connecting pipe path and an air pipe path for feeding air. CONSTITUTION:The confluence of a channel-connecting pipe path 9 and a disinfectant soln. pipe path 28 for feeding a disinfectant soln. is positioned on the downstream side of the confluence of the channel-connecting pipe path 9 and an air pipe path 24 for feeding air. The washing liq. remaining in a flow path for the disinfectant soln. in the channel-connecting pipe path 9 is removed by the air fed from the air pipe path 24 to the channel-connecting pipe path 9 when air-feed motion is performed at the last half of a washing process. The remaining water in the channel pipe path can be surely removed thereby and even when the number of repeating of washing and disinfection work for an endoscope is increased, the disinfectant soln. can be prevented from being diluted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope cleaning / disinfecting apparatus provided with a channel connecting pipe which leads into a channel of an endoscope.

[0002]

2. Description of the Related Art Generally, an endoscope cleaning / disinfecting apparatus is provided with a cleaning tank for cleaning the entire endoscope. In addition, a washing tube that connects to each channel such as the suction channel of the endoscope and the air / water feeding channel is installed in the washing tank, and this washing is performed at the time of cleaning / disinfecting each channel of the endoscope suction channel, air / water feeding channel, etc. The tube is connected to the channel of the endoscope, and the cleaning water, the disinfectant solution, etc. are supplied into the channel through the cleaning tube.

By the way, in the endoscope cleaning / disinfecting apparatus, it is necessary to circulate a pipe for supplying at least the cleaning liquid, the disinfecting liquid, and the air to the cleaning tube. In this case, in order to simplify the pipeline structure in the endoscope cleaning / disinfecting apparatus, the channels are joined into one shared pipeline and then guided to the cleaning tube.

[0004]

When the pipes for supplying the cleaning liquid, the disinfecting liquid, and the air are merged into one combined pipe and then the pipes are guided to the cleaning tube as in the conventional structure described above. In the cleaning process, the cleaning liquid circulated in the dual-purpose conduit may remain in the dual-purpose conduit even after the cleaning process is completed and the cleaning liquid is drained. In this case, there is a possibility that the liquid remaining in the dual-use conduit may be mixed with the disinfectant solution supplied in the subsequent disinfecting step to dilute the disinfectant solution.

Further, in this type of endoscope cleaning / disinfecting apparatus, generally, the disinfecting solution is repeatedly used. Therefore, the dilution of the disinfecting solution at least once causes the disinfecting effect to be gradually mixed by repeating the mixing of the cleaning solution. There was a problem of decline.
Therefore, it is difficult to always maintain the disinfecting effect of the endoscope at a certain level or more, and the disinfecting effect of the endoscope gradually decreases as the number of repetitions of the cleaning and disinfecting work of the endoscope gradually decreases, resulting in poor disinfection. It was likely to occur.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent dilution of a disinfecting solution even when the number of times of cleaning and disinfecting operations of an endoscope is increased. An object is to provide an endoscope cleaning / disinfecting apparatus.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a channel connecting pipe which communicates with a channel of an endoscope, a cleaning liquid pipe for supplying a cleaning liquid to the channel connecting pipe, and a disinfectant liquid for supplying a disinfectant liquid. In an endoscope cleaning / disinfecting apparatus to which a pipe line and an air pipe line for supplying air are respectively connected, a confluence point of the channel connecting pipe line and a disinfectant liquid pipe line for supplying a disinfectant liquid is defined as the channel connecting pipe. It is arranged on the downstream side with respect to the confluence of the passage and the air pipeline for supplying air.

[0008]

The cleaning liquid remaining in the flow path of the disinfecting liquid in the channel connecting conduit is removed by the air sent from the air conduit into the channel connecting conduit during the air feeding operation performed in the latter half of the cleaning process. It was done like this.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present invention will now be described with reference to FIG.
It will be described with reference to FIGS. FIG. 1 shows a schematic configuration of an endoscope cleaning / disinfecting apparatus, and 1 is a main body of the endoscope cleaning / disinfecting apparatus.

A cleaning tank 2 having an open front is arranged in the apparatus main body 1. Front opening 2 of this cleaning tank 2
As shown in FIGS. 3B and 3C, a is closed in a watertight state by an opening / closing door 2b.

Further, a rack 4 for accommodating the endoscope 3 is provided inside the cleaning tank 2. An upper surface of the rack 4 is opened, and the rack 4 is formed by a container having a depth that allows at least the entire endoscope 3 to be immersed. The rack 4 can be taken out of the cleaning tank 2.

Further, in the cleaning tank 2, a cleaning nozzle 5 is mounted on the ceiling surface, an injection pipe body 6 and a connection port body 10 are mounted on the side wall surface, and a drain port body 32 is mounted on the inner bottom surface. in this case,
The cleaning nozzle 5 and the injection port of the injection pipe body 6 are arranged above the rack 4.

As shown in FIG. 2, the rack 4 is provided with a first connecting portion 7 on the side wall surface and a second connecting portion 8 on the inner bottom surface. In this case, one end of the washing tube 9 in the rack 4 is detachably attached to the inside of the first connecting portion 7. Further, at the other end of the cleaning tube 9, there is provided a connection mouthpiece 9a detachably connected to a channel inside the endoscope 3. Also, the second connecting portion 8
The drain port 32 on the cleaning tank 2 side is detachably connected to the.

Further, a water supply tank 12 is provided in the apparatus body 1.
And a disinfectant solution tank 13 are provided respectively. A water supply hose 14 is connected to the water supply tank 12 via a water supply valve 15, and the detergent dispenser 1
6, the disinfectant solution dispenser 17, and the base end of the cleaning solution conduit 18 are connected to each other. A first liquid feed pump 19 is provided in the cleaning liquid conduit 18.

The tip of the cleaning liquid conduit 18 is connected to the cleaning nozzle 5. Further, the base end of the channel connecting pipe 11 and the base end of the auxiliary pipe 21 are connected to the downstream side of the first liquid feed pump 19 in the middle of the cleaning liquid pipe 18.

The tip of the channel connecting pipe 11 is connected to the first connecting portion 7 of the rack 4 via the connecting port 10 of the cleaning tank 2.
It is detachably connected to the outside of the. The tip of the auxiliary pipe 21 is connected to a joint 22 mounted on the outer surface of the case of the apparatus body 1. This joint part 2
2, a water supply joint 23 attached to the tip of the water supply hose 14 is detachably connected.
The water supply joint 23 is in an open state when connected to the joint portion 22 of the auxiliary pipeline 21. The auxiliary conduit 21 is arranged with an inclination in a direction in which the joint portion 22 is raised so that residual water does not occur in the conduit.

Further, one ends of an air conduit 24 for supplying air and a disinfecting liquid conduit 28 for supplying a disinfectant liquid are connected to a middle portion of the channel connecting conduit 11. In this case, a confluence point (second confluence point) 30 of the channel connection duct 11 and the disinfectant liquid duct 28 is a confluence point of the channel connection duct 11 and the air duct 24 (first confluence point). It is arranged on the downstream side with respect to 27.

The other end of the air conduit 24 is connected to an intake port 24a mounted on the outer surface of the case of the apparatus body 1. Further, an air filter 25 is provided in the middle of the air pipe 24, and an air supply pump 26 is provided downstream of the air filter 25.

The other end of the disinfectant solution line 28 is connected to the disinfectant solution tank 13. Furthermore, this disinfectant liquid line 2
A second liquid feed pump 29 is provided in the middle of 8, and one end of a branch pipe line 31 is connected to the downstream side of the second liquid feed pump 29. The other end of the branch pipe 31 is connected to the base end of the injection pipe 6 via a connection port 31a attached to the cleaning tank 2.

Further, the drainage port body 32 of the cleaning tank 2 is the drainage channel 3
3 to the inlet port of the three-way valve 34.
The first outlet port of the three-way valve 34 is connected to the disinfectant solution tank 13 via a connecting pipe 35.

Further, the second outlet port of the three-way valve 34 is connected via a drainage pipe 36 to a drainage port 36a mounted on the outer surface of the case of the apparatus body 1. A drainage pump 37 is provided in the middle of the drainage pipe 36. The three-way valve 34 closes the drainage channel 33, a collection position that communicates between the drainage channel 33 and the connection pipeline 35, and a drainage position that communicates between the drainage channel 33 and the drainage pipeline 36. It is designed to be switched to each.

In the middle of the channel connecting pipe 11, a second junction is formed between the first junction 27 and the second junction 30.
A first check valve 38 for preventing the reverse flow of fluid from the side of the confluence point 30 to the side of the first confluence point 27, and a reverse flow of the fluid from the side of the first confluence point 27 to the side of cleaning liquid pipeline 18. Each second check valve 39 is provided. Further, the channel connecting conduit 11 is set so that the inner diameter of the downstream conduit 11b of the second confluence 30 is smaller than the inner diameter of the upstream conduit 11c, and the second confluence 30 The narrowed portion 11a of the flow path is formed in the portion.

The first connecting portion 7 and the second connecting portion 8 of the rack 4 are connected to the tip of the channel connecting pipe 11 on the side of the cleaning tank 2 when the rack 4 is housed in the cleaning tank 2. The drainage port body 32 is automatically connected.

Next, the operation of the above configuration will be described.
First, when the endoscope cleaning / disinfecting apparatus is used, the opening / closing door 2b of the cleaning tank 2 is opened, and the rack 4 is taken out of the cleaning tank 2 as shown in FIG. Then, the washing tube 9 is attached to the first connecting portion 7 of the rack 4 outside the washing tank 2, and the endoscope 3 is installed. Further, the connection mouthpiece 9a of the cleaning tube 9 is set in a state of being connected to the channel in the endoscope 3.

After the endoscope 3 and the like are set in the rack 4, the rack 4 is housed in the cleaning tank 2 at a predetermined installation location through the front opening 2a of the cleaning tank 2. At this time, when the rack 4 is stored at a predetermined installation place in the cleaning tank 2, the first connecting portion 7 and the second connecting portion 8 of the rack 4 cause the tip of the channel connecting pipe line 11 on the cleaning tank 2 side. Part and drainage body 3
2 is automatically connected.

With the rack 4 housed inside the cleaning tank 2 as described above, the opening / closing door 2b of the cleaning tank 2 is closed, and the cleaning / disinfecting operation of the endoscope 3 by this endoscope cleaning / disinfecting apparatus is started. It In this case, the cleaning / disinfecting operation of the endoscope 3 is performed by sequentially performing the following three steps of cleaning / disinfecting / rinsing and, if necessary, in-apparatus disinfecting steps.

First, in the cleaning process, with the water supply joint 23 of the water supply hose 14 connected to, for example, a tap, the tap of the tap water is opened to supply tap water to the water supply tank 12 via the water supply hose 14. At the same time, the detergent concentrate is poured into the water supply tank 12 from the detergent dispenser 16. Then, the detergent concentrate is diluted with tap water to an appropriate concentration in the water supply tank 12, and the detergent liquid having the appropriate concentration is stored in the water supply tank 12.

Next, in this state, the three-way valve 34 is connected to the drainage channel 33.
The first liquid transfer pump 19 is driven while being switched to a drainage position that communicates between the drainage pipe 36 and the drainage pipe 36.
Then, the detergent liquid in the water supply tank 12 is passed through the washing liquid pipe 18 by the first liquid feeding pump 19 to the washing nozzle 5
And to the channel connecting pipe 11.

Then, as shown in FIG. 3B, the entire outer surface of the endoscope 3 is cleaned by the detergent liquid sprayed from the cleaning nozzle 5, and the channel connecting conduit 11 and the cleaning tube 9 are used. A detergent liquid is supplied to the channel in the endoscope 3 to clean the inside of the channel.

Further, the air supply pump 26 is driven in the latter half of this cleaning process. Then, the air sucked into the air conduit 24 from the intake port 24a by the air supply pump 26 is supplied to the channel connecting conduit 11 through the air filter 25 to drain the channel of the endoscope 3.

In the disinfection process, the three-way valve 34 is installed in the drainage channel 3
The second liquid feed pump 29 is driven while the switching operation is performed to the closing position where the third liquid is closed. Then, the disinfectant solution stored in the disinfectant solution tank 13 is supplied into the disinfectant solution conduit 28 by the second liquid sending pump 29, and further, from this disinfectant solution conduit 28, the branch conduit 31 and the channel connecting pipe. Each is supplied to the path 11.

Further, the disinfectant solution in the branch pipe 31 is shown in FIG.
As shown in (C), it is injected into the rack 4 from the injection port of the injection pipe body 6 and is stored in the rack 4 to immerse and disinfect the endoscope. Further, the disinfecting liquid supplied to the channel connecting pipes 11 is supplied to the channels in the endoscope 3 through the cleaning tube 9 and the channels are disinfected.

After the disinfection is completed, the three-way valve 34 is switched to the recovery position where the drainage channel 33 and the connecting duct 35 communicate with each other. Therefore, the disinfectant solution stored in the rack 4 is collected in the disinfectant solution tank 13 via the drainage channel 33 and the connecting pipe channel 35.

In the rinsing step, tap water is supplied to the water supply tank 12 via the water supply hose 14. Next, the three-way valve 34 is switched to the drainage position where the drainage channel 33 and the drainage channel 36 communicate with each other, and the first liquid feed pump 19 is driven. Then, this first liquid feed pump 19
Thus, the water in the water supply tank 12 is supplied to the cleaning nozzle 5 and the channel connecting pipe 11 via the cleaning liquid pipe 18.

Then, rinsing water is sprayed from the cleaning nozzle 5 onto the entire outer surface of the endoscope 3 to wash away the residual disinfecting liquid adhering to the outer surface of the endoscope 3. Further, the residual disinfectant solution in the channel is washed away by the rinse water supplied from the channel connecting conduit 11 to the channel in the endoscope 3 through the cleaning tube 9.

Further, in the latter half of this rinsing step, the air supply pump 26 is driven similarly to the cleaning step, and the air drawn into the air duct 24 from the intake port 24a by the air supply pump 26 passes through the air filter 25. The water is supplied to the channel connecting pipe 11 to drain the channel of the endoscope 3.

After the rinsing step is completed, an in-apparatus disinfection step is performed if necessary. In this in-apparatus disinfection process, for example, the tap of tap water such as a tap is closed, and the water supply joint 23 is removed from the tap. This water supply joint 2
3 is connected to the joint portion 22 of the auxiliary pipeline 21 with one touch. This joint part 22 is a water supply joint 23.
It is opened by connecting with.

In this state, when the in-apparatus disinfection step is subsequently performed, the concentrated disinfectant solution is first supplied from the disinfectant solution dispenser 17 to the water supply tank 12. Since tap water is stored in the water supply tank 12, the concentrated disinfectant solution is dissolved in the tap water, and the disinfectant solution having an appropriate concentration is generated in the water supply tank 12.

After that, by performing substantially the same operation as in the washing step, the disinfectant solution flows through each pipe line inside the apparatus main body 1, so that bacterial propagation in each pipe line inside the device main body 1 is prevented. can do.

Further, during the disinfection process in the apparatus, the auxiliary pipeline 2
Since the first joint portion 22 is open, part of the disinfectant liquid supplied by the first liquid feed pump 19 returns to the water supply tank 12 via the auxiliary pipeline 21 and the water supply hose 14. In this process, the water supply hose 14 is also disinfected. Then, when the disinfecting liquid in the water supply tank 12 is exhausted, the in-apparatus disinfecting process is completed.

In the apparatus disinfection step, the user can select whether or not to perform the apparatus disinfection step by operating an operation panel (not shown) mounted on the outer surface of the case of the apparatus body 1. In general, the in-apparatus disinfection step can be performed once at the end of the day to keep the inside of the apparatus main body 1 (mainly the rinse water circulation passage) clean.

The disinfecting solution used in the disinfecting process in the apparatus may be an inexpensive disinfecting solution such as amphoteric soap water or reverse soap water, as long as it has the effect of preventing the proliferation of various bacteria in the apparatus main body 1. ..

Therefore, in the above-described structure, the second confluence point 30 between the disinfectant liquid conduit 28 and the channel connecting conduit 11 is the first joining point between the air conduit 24 and the channel connecting conduit 11. Since it is disposed on the downstream side of the confluence point 27, the cleaning liquid remaining in the flow path of the disinfecting liquid in the channel connecting pipe line 11 is discharged from the air pipe line 24 to the channel during the air feeding operation performed in the latter half of the cleaning process. It is possible to surely remove the air by the air sent into the connecting pipe line 11. Therefore, even when the number of repetitions of the cleaning and disinfecting operation of the endoscope 3 increases, it is possible to prevent the disinfectant solution in the disinfectant solution tank 13 from being diluted.

Further, the channel connecting pipe 11 is the second
The inner diameter of the conduit 11b on the downstream side of the confluence point 30 is set to be smaller than the inner diameter of the conduit 11c on the upstream side,
Since the narrowed portion 11a of the flow passage is formed at the portion of the second junction point 30, the effect of removing the cleaning liquid remaining in the flow passage of the disinfecting liquid in the channel connecting pipe passage 11 can be further enhanced.

Further, since the cleaning tank 2 whose front opening 2a is opened / closed by the opening / closing door 2b is provided and the rack 4 having an open upper surface is removably accommodated in the cleaning tank 2, it is a side opening / closing type. It is possible to prevent problems such as leakage of the disinfectant solution to the outside of the cleaning tank 2. Therefore, it is possible to reduce the floor area of the cleaning tank 2 when performing the disinfection operation by the disinfecting liquid immersion method.

Further, since the rack 4 is provided with the watertight function when the disinfectant is immersed, the highly watertight structure of the opening / closing part of the cleaning tank 2 can be omitted. Therefore, a relatively inexpensive side opening / closing type cleaning tank 2 can be manufactured.

Further, since the cleaning liquid pipe 18 is provided with the auxiliary pipe 21 and the end of the water supply hose 14 is detachably connected to the auxiliary pipe 21, the apparatus main body 1 by the first liquid feed pump 19 is used. When supplying the disinfectant solution to the inside, supply water hose 14
The inside can be disinfected at the same time. Therefore, the inside of the water supply hose 14 can be easily and surely disinfected.

A heater and a temperature sensor are attached to the water supply hose 14, the water in the water supply hose 14 is heated by the heater as necessary, and the temperature of the water in the water supply hose 14 is kept at 60 ° C. or higher for a certain time or longer. Hold and water supply hose 14
You may make it the structure which kills the miscellaneous bacteria adhering to the inner surface of.

FIGS. 4 and 5 show a second embodiment of the present invention. Here, FIG. 4 shows a schematic configuration of the endoscope cleaning / disinfecting apparatus, and 41 is a cleaning tank.
A rack 42 for housing the endoscope 3 is provided in the cleaning tank 41, an upper nozzle 43 is provided at an upper portion of the cleaning tank 41, a lower nozzle 44 is provided at a lower portion thereof, and a water supply port 45 is provided at a side wall portion. Channel connecting pipes 46 are provided respectively.

Reference numeral 47 is a cleaning liquid conduit. The base end of the cleaning liquid conduit 47 is connected to the water faucet 48 via a water supply hose 49. Further, an upper nozzle 43, a lower nozzle 44, and a channel connecting pipe 46 are connected to the tip end side of the cleaning liquid pipe 47, respectively.

An unillustrated disinfectant liquid line for supplying the disinfectant solution and an unillustrated air line for supplying the air are connected to the channel connecting conduit line 46, respectively.
The confluence of the channel connecting pipe 46 and the disinfecting liquid pipe is arranged downstream of the confluence of the channel connecting pipe 46 and the air pipe.

Further, inside the water supply hose 49, as shown in FIG. 5, two water supply pipes 50 and 51 are formed.
Further, a solenoid valve 52 is provided at the water supply source mounting port of the water supply hose 49, and two pipe lines 50 in the water supply hose 49 are provided.
The base end portions of 51 are communicated with each other via a check valve 53 that prevents fluid from flowing from the water supply pipe line 50 side to the water supply pipe line 51 side.

The tip of one of the water supply conduits 50 is connected to the water supply port 45, and the tip of the other water supply conduit 51 is connected to the cleaning liquid conduit 47. Further, the cleaning liquid pipe 47 is connected to the drain port 54 of the cleaning tank 41, and the other end of a connecting pipe 55 is connected to the drain port 54. A washing pump 56 is provided in the middle of the connecting pipe 55.

Therefore, in the above-described structure, the cleaning liquid supplied from the cleaning pump 56 is sprayed from the upper nozzle 43 and the lower nozzle 44 to the endoscope 3 in the cleaning tank 41 through the cleaning liquid conduit 47 during the cleaning process. The outer surface of the endoscope 3 is washed. At the same time, it is supplied from the cleaning liquid conduit 47 into the channel of the endoscope through the channel connecting conduit 46, and the inside of the channel of the endoscope is cleaned.

On the other hand, part of the cleaning liquid ejected from the cleaning pump 56 passes through the water supply pipe line 51 in the water supply hose 49, the check valve 53, and the other water supply pipe line 50 in the water supply hose 49, and the cleaning tank 41. Will be recovered in. That is, all of the water supply pipelines and the cleaning pipeline system are cleaned.

After that, also in the disinfection process, the cleaning pump 5 is similarly used.
The disinfecting liquid supplied from 6 is sprayed onto the endoscope 3 to disinfect the endoscope 3, and at the same time, flows into all of the water supply and cleaning pipeline systems to disinfect each pipeline.

Further, in FIG. 6, a two-way switching solenoid valve 61 having a switching function is used in place of the solenoid valve 52 and the check valve 53 of the water supply hose 49 of FIG. In this case, the two-way switching solenoid valve 61 is switched to the b position during water supply and to the a position at other times. At the position a, the water supply from the water faucet 48 is stopped, and one water supply pipe 50 and the other water supply pipe 51 in the water supply hose 49 are in communication with each other. Then, at the time of cleaning and disinfecting processes, the liquid from the cleaning pump 56 passes through these pipes 51,
It returns to the inside of the washing tank 41 through 50 and is circulated.

Therefore, in this case, the water supply hose 49
Since the configuration of can be made simpler, the number of failures can be reduced and the cost can be reduced. Further, since the water supply hose 49 is cleaned and disinfected automatically at the same time as the cleaning and disinfection of the endoscope 3, the water supply hose 49 is not contaminated and the entire apparatus is kept clean. Therefore, it is not necessary to perform troublesome disinfection in the apparatus.

[0059]

According to the present invention, the confluence of the channel connecting conduit and the disinfectant liquid supplying the disinfectant solution is set to the confluence of the channel connecting conduit and the air supplying air conduit. Since it is placed on the downstream side, it is possible to reliably remove residual water in the channel conduit and prevent dilution of the disinfecting solution even when the number of times the endoscope cleaning and disinfecting work is repeated. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an endoscope cleaning / disinfecting apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a rack of a cleaning tank.

FIG. 3 is a view for explaining the operation of the first embodiment,
(A) is a schematic configuration diagram showing a state in which a rack is removed from a cleaning tank, (B) is a schematic configuration diagram showing a cleaning step, and (C) is a schematic configuration diagram showing a disinfection step.

FIG. 4 is a schematic configuration diagram of an endoscope cleaning / disinfecting apparatus according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a water supply hose.

FIG. 6 is a schematic configuration diagram showing a modified example of a water supply hose.

[Explanation of symbols]

9, 46 ... Channel connecting conduits, 18, 47 ... Cleaning liquid conduits, 24 ... Air conduits, 28 ... Disinfectant liquid conduits.

Claims (1)

[Claims] 1. A channel connecting pipe communicating with a channel of an endoscope is provided, and a cleaning liquid pipe supplying a cleaning liquid, a disinfecting liquid pipe supplying an antiseptic liquid, and air are supplied to the channel connecting pipe. In an endoscope cleaning / disinfecting apparatus to which air pipes are respectively connected, a confluence point between the channel connecting pipe and the disinfecting liquid pipe supplying the disinfectant liquid is determined by an air supplying air supplying the channel connecting pipe. An endoscope cleaning / disinfecting apparatus, which is arranged on a downstream side with respect to a confluence point with a pipeline.