JP7443736B2 - Piping system design method, piping system design support device, program, and piping system - Google Patents

Description

The present invention relates to a method for designing a piping system having branch pipes in which dead legs are formed, a piping system design support device, a program installed in the design support device, and a piping system.

Factories that produce pharmaceuticals, precision mechanical parts, electronic parts, etc. are equipped with piping systems that supply water to use points installed at various locations. The piping system includes a main pipe through which water supplied by a supply source flows and branch pipes branching from the main pipe. An example of a branch pipe is a pipe that is provided with an on-off valve as a closing mechanism at its tip and carries water to a point of use. Another example of a branch pipe is a pipe that is equipped with a meter at its tip as a closure mechanism. In such branch pipes, when water is in a stagnant state, dead legs are formed where there is a concern that water quality may deteriorate due to the stagnation of the water. In order to suppress the deterioration of water quality due to such dead legs, Non-Patent Document 1 states that the dead leg length, which indicates the distance from the center of the main pipe to the closing mechanism at the tip of the branch pipe, is set at 60% of the inner diameter of the branch pipe, as a guideline by the Japanese Ministry of Health, Labor and Welfare. It is stated that the amount should be increased within twice as much, and if possible, within 3 times.

Comparison of GMP structural and equipment requirements Manufacturing water equipment 001: Definition and setting of dead legs, [online], General Incorporated Association Society of Pharmaceutical Machinery Technology homepage, [Retrieved June 28, 2018] Internet, <URL: https://www. seikiken. or. jp/gmp/gmp_hikaku/hikaku. html#yousui001>

In the piping system described above, in order to improve the degree of freedom regarding the length of the branch pipes while complying with the guidelines of the Japanese Ministry of Health, Labor and Welfare, it is necessary to increase the diameter of the branch pipes. However, increasing the diameter of the branch pipe increases the cost of the entire system. Therefore, in such piping systems, it is required to suppress the increase in cost and the decrease in water quality caused by dead legs.

A method of designing a piping system that solves the above problem is a method of designing a piping system that includes a main pipe through which water supplied by a supply source flows, and a plurality of branch pipes branching from the main pipe and each having a closing mechanism at the tip. When the length from the center of the main pipe to the closing mechanism and expressed as a relative value to the inner diameter of the branch pipe is the dead leg length, the use of the piping system for each of the plurality of branch pipes is Based on the prediction, an individual minimum flow velocity of the water flowing through the connecting portion of the branch pipe in the main pipe is determined, and an allowable value for the dead leg length is set according to the individual minimum flow velocity.

A piping system design support device that solves the above problems is a piping system design support device that includes a main pipe through which water supplied by a supply source flows, and a plurality of branch pipes that branch from the main pipe and are provided with a closing mechanism at their tips. When the length from the center of the main pipe to the closing mechanism and expressed as a relative value to the inner diameter of the branch pipe is the dead leg length, the design support device determines the length of the plurality of branch pipes. a calculation unit that calculates the individual minimum flow rate of the water flowing through the connection portion of the branch pipes in the main pipe, based on the usage prediction of the piping system; an allowable value setting section that sets an allowable value for the dead leg length according to the above.

The program that solves the above problem is a design support device that supports the design of a piping system that includes a main pipe through which water supplied by a supply source flows, and a plurality of branch pipes that branch from the main pipe and are provided with a closing mechanism at the tip. , when the length from the center of the main pipe to the closing mechanism and expressed as a relative value to the inner diameter of the branch pipe is the dead leg length, use prediction of the piping system for each of the plurality of branch pipes. , a process of determining the individual minimum flow velocity of the water flowing through the connection portion of the branch pipes in the main pipe, and determining an allowable value of the dead leg length for each of the plurality of branch pipes according to the individual minimum flow velocity. This is a program that executes the settings.

A piping system that solves the above problems is a piping system that includes a main pipe through which water supplied by a supply source flows, and a plurality of branch pipes branched from the main pipe and each having a closing mechanism at its tip. For each of the branch pipes, when the dead leg length is the length from the center of the main pipe to the closing mechanism and expressed as a relative value to the inner diameter of the branch pipe, the length of the main pipe with respect to the supply source The dead leg length monotonically decreases from the branch pipe located most upstream of the main pipe to the branch pipe located most downstream of the main pipe.

According to the present invention, it is possible to suppress an increase in the cost of a piping system and a decrease in water quality caused by dead legs.

The figure which shows the schematic structure of the piping system for a test used for evaluation of dead leg length. A graph showing an example of measurement results when the flow velocity is 0.5 m/s. A graph showing an example of measurement results when the flow velocity is 1.0 m/s. A graph showing an example of measurement results when the flow velocity is 1.5 m/s. FIG. 1 is a diagram schematically showing an embodiment of a piping system. 1 is a flowchart showing an example of a piping system design procedure. FIG. 1 is a block diagram showing an embodiment of a design support system. (a) A diagram schematically showing a state in which a branch pipe is connected to the main pipe at an acute angle in a modified example, and (b) a diagram schematically showing a state in which a branch pipe is connected to the main pipe at an obtuse angle in a modified example.

A piping system design method, a piping system design support device, a program installed in the design support device, and an embodiment of the piping system will be described with reference to FIGS. 1 to 8.

In the piping system design method of this embodiment, the dead leg length is evaluated using a test piping system, and an allowable value for the dead leg length is set based on the evaluation result. Then, by designing the piping system based on the set allowable value of the dead leg length, an increase in cost and a decrease in water quality caused by the dead leg are suppressed.

(Test piping system)
As shown in FIG. 1, the test piping system 10 includes a source 11 that provides clean, colorless water. The supply source 11 includes a tank 12 that stores colorless water, and a pump 13 that supplies the colorless water in the tank 12 to the main pipe 15. The pump 13 is a metering pump, and supplies colorless water to the main pipe 15 at a preset flow rate. The main pipe 15 is a pipe having a constant cross-sectional area based on the main pipe inner diameter A, and is configured to be able to circulate colorless water using the supply source 11 as a reference. The test piping system 10 has a first bypass pipe 16 that connects the main pipe 15 downstream of the pump 13 and the tank 12 . A first bypass valve 17 is provided in the first bypass pipe 16 . The test piping system 10 is configured such that the flow rate of colorless water flowing through the main pipe 15 can be adjusted by adjusting the first bypass valve 17.

The test piping system 10 includes a flow rate measuring section 20 that measures the flow rate in the main pipe 15 on the downstream side of the connection portion of the first bypass pipe 16 to the main pipe 15 . The flow measurement section 20 of the test piping system 10 has a first flow measurement path 21 and a second flow measurement path 22, which are two flow paths branching from the main pipe 15. The first flow rate measurement path 21 is provided with a first flow meter 23 that is a flow meter for large flow rates, and a first regulating valve 24 that adjusts the first flow rate measurement path 21 on the upstream side of the first flow meter 23. It is set up. The second flow rate measurement path 22 is provided with a second flow meter 25 that is a flow meter for small flow rates and a second regulating valve 26 that adjusts the second flow rate measurement path 22 on the upstream side of the second flow meter 25. It is set up. The test piping system 10 is configured such that the flow rate measurement unit 20 is roughly adjusted by the first adjustment valve 24 and finely adjusted by the second adjustment valve 26 based on the measured values of the first flowmeter 23 and the second flowmeter 25. The flow rate of colorless water passing through is adjusted with precision.

The test piping system 10 has a test section 29 downstream of the flow rate measurement section 20 . The test section 29 has a branch pipe 30, a first cutoff valve 31, and a second cutoff valve 32. The branch pipe 30 serving as a closing mechanism whose tip is closed is a straight pipe connected to a connecting portion 35 of the main pipe 15 by a coupler. The branch pipe 30 is a pipe whose angle θ with respect to the main pipe 15 located upstream of the branch pipe 30 is set to 90°. Branch pipe 30 is a site where a dead leg is formed. The length of the part where this dead leg is formed is expressed as the dead leg length. The dead leg length is a length expressed as a relative value to the branch pipe inner diameter D, which is the inner diameter of the branch pipe 30, and is expressed as, for example, 6D.

The first cutoff valve 31 and the second cutoff valve 32 are on-off valves that can open and close the main pipe 15. The first cutoff valve 31 is disposed on the upstream side of the connection portion 35 of the main pipe 15, and the second cutoff valve 32 is disposed on the downstream side of the connection portion 35 of the main pipe 15.

The test section 29 has a first cutoff valve 31, a branch pipe 30, and a second bypass pipe 36 connected to the main pipe 15 so as to bypass the second cutoff valve 32. A second bypass valve 37 is provided in the second bypass pipe 36 . The second bypass valve 37 is controlled to be in the closed state when both the first cutoff valve 31 and the second cutoff valve 32 are in the open state, and both the first cutoff valve 31 and the second cutoff valve 32 are in the closed state. It is controlled to be open at certain times.

The test piping system 10 has a drain pipe 38 downstream of the test section 29 . The drain pipe 38 is a pipe that branches from the main pipe 15 and has an open downstream end. The drain pipe 38 is provided with a drain valve 39 that can open and close the drain pipe 38 . The test piping system 10 has a circulation valve 40 downstream of the connection portion of the drain pipe 38 to the main pipe 15 .

The test piping system 10 has a test state and a non-test state. In the test state, both the first cutoff valve 31 and the second cutoff valve 32 are in an open state, the second bypass valve 37 is in a closed state, the drain valve 39 is in an open state, and the circulation valve 40 is in a closed state. On the other hand, in the non-test state, both the first cutoff valve 31 and the second cutoff valve 32 are in a closed state, and the second bypass valve 37 is in an open state.

That is, the test piping system 10 is configured such that, in the test state, the colorless water that has flowed into the test section 29 flows through the connecting portion 35 of the main pipe 15 and is then drained to the outside through the drain pipe 38. In addition, in the test piping system 10, in a non-test state, the colorless water that has flowed into the test section 29 flows through the second bypass pipe 36 instead of the connecting part 35 of the main pipe 15, and the branch pipe 30 and the connecting part 35 are replaced. configured to be possible.

(Evaluation method)
A method for evaluating the dead leg length using the test piping system 10 described above will be described. In this embodiment, after controlling the connection part 35 and the branch pipe 30 to a non-test (non-circulation) state and filling them with colored water at a predetermined concentration, the test piping system 10 is controlled to the test state, and the subsequent branch The dead leg length was evaluated based on the change in the concentration of colored water in the tube 30.

Specifically, first, a branch pipe 30 having a dead leg length of a desired test length was filled with a methylene blue aqueous solution having an initial concentration of 2.4 mmol/L, and the test piping system 10 was controlled to a test state. Then, each time a desired measurement time elapsed, a test liquid was collected from the tip of the branch pipe 30, and the dead leg length was evaluated by measuring the concentration of methylene blue by spectroscopically measuring the collected test liquid. For spectroscopic measurement, a spectrometer with a lower limit of quantification of 0.00064 mmol/L was used.

In this embodiment, the main pipe 15 is made of a vinyl chloride pipe with a nominal diameter of 50A, and the branch pipe 30 is made of a vinyl chloride pipe with a nominal diameter of 40A. In addition, the test length of the dead leg length is 3D, 6D that meets the guidelines of the Japanese Ministry of Health, Labor and Welfare, and the test flow rate is 0.5 m/s, 1.0 m/s, 1.5 m, which is the flow speed that suppresses the corrosion rate of the main pipe 15. The dead leg length was evaluated as /s. The test flow rate was calculated based on the flow rate measured by the flow rate measuring section 20 and the flow path cross-sectional area S of the main pipe 15. For each test condition, pass/fail was determined depending on whether the measured concentration after 60 seconds was 1/10 or less of the initial concentration.

(Evaluation results)
Examples of measurement results are shown in Figures 2, 3, and 4. FIG. 2 shows the measurement results when the test flow rate is 0.5 m/s, and FIG. 3 shows the measurement results when the test flow rate is 1.0 m/s. FIG. 4 shows the measurement results when the test flow velocity was 1.5 m/s. Note that the plots shown in FIGS. 2 to 4 show main measurement results among the obtained measurement results. Further, the two-dot chain line in the figure indicates a pass/fail boundary line where the measured density after 60 seconds is 1/10 of the initial density. A plot located below this two-dot chain line is a plot that is judged to be good.

As shown in Figure 2, under the conditions of a test flow rate of 0.5 m/s and a dead leg length of 3D, the measured concentration after 30 seconds was lower than 1/10 of the initial concentration, and the measured concentration after 60 seconds was lower than 1/10 of the initial concentration. It was observed that the concentration was lower than 1/100 of the initial concentration. That is, a good judgment was obtained for the dead leg length 3D at a test flow rate of 0.5 m/s.

Furthermore, under the conditions of a test flow rate of 0.5 m/s and a dead leg length of 6D, the measured concentration after 60 seconds is higher than 1/10 of the initial concentration, and the measured concentration decreases to 1/10 or less of the initial concentration. It was recognized that about 120 seconds were required for this. That is, a negative determination was obtained regarding the dead leg length at a test flow rate of 0.5 m/s.

As shown in Figure 3, under the conditions of a test flow rate of 1.0 m/s and a dead leg length of 3D, the measured concentration decreased to 1/10 or less of the initial concentration after 15 seconds, and the measured concentration decreased to 1/10 of the initial concentration after 45 seconds. It was observed that the value decreased to /100 or less. Furthermore, under the conditions of a test flow rate of 1.0 m/s and a dead leg length of 6D, it was observed that the measured concentration decreased to 1/10 or less of the initial concentration after 60 seconds. That is, under the test flow velocity of 1.0 m/s, good judgments were obtained for both dead leg lengths of 3D and 6D.

As shown in Figure 4, under the conditions of a test flow rate of 1.5 m/s and a dead leg length of 3D, the measured concentration decreased to 1/10 or less of the initial concentration after 15 seconds, and the measured concentration decreased to 1/10 of the initial concentration after 45 seconds. It was observed that the value decreased to /100 or less. Furthermore, under the conditions of a test flow rate of 1.5 m/s and a dead leg length of 6D, it was observed that the measured concentration decreased to 1/10 or less of the initial concentration after 60 seconds. That is, under the test flow velocity of 1.5 m/s, good judgments were obtained for both dead leg lengths of 3D and 6D.

Through such evaluation of the dead leg length, the present inventors found that the higher the flow velocity in the connecting portion 35, the less likely the methylene blue aqueous solution is to stay in the branch pipe 30, that is, the easier it is to keep the water in the branch pipe 30 clean. . The present inventors evaluated the dead leg length under various conditions when the angle θ formed by the branch pipe 30 with respect to the main pipe 15 was 90°, and determined the flow velocity of the connecting portion 35 and the dead leg length. We found a relationship with the allowable value of .

(Piping system design procedure)
With reference to FIGS. 5 and 6, a procedure for designing a piping system will be described using an example of a piping system. FIG. 5 is a diagram showing a piping system to be designed in this embodiment. FIG. 6 is a flowchart illustrating an example of a piping system design procedure.

FIG. 5 shows a piping diagram of the usage state of the piping system, as well as usage prediction information indicating the amount of usage at each time for some use points. In addition, in the piping system shown in FIG. 5, parts having the same functions as those in the test piping system shown in FIG.

As shown in FIG. 5, in the piping system 41, water is supplied to the main pipe 15 by a supply source 11 composed of a tank 12 and a pump 13. Branch pipes 30 are connected to various parts of the main pipe 15. An example of the branch pipe 30 is a pipe through which water flows toward each use point, and an on-off valve 42A is provided as a closing mechanism at the tip thereof. Another example of the branch pipe 30 is a pipe for measuring the properties of the water flowing through the main pipe 15, and a meter 42B is disposed at the tip thereof as a closing mechanism. A flow control valve 43 that controls the flow of water in the main pipe 15 is disposed between the connection portion of the first bypass pipe 16 and the most upstream branch pipe 30 in the main pipe 15 . Note that an example of the main pipe 15 and the branch pipe 30 is a stainless steel pipe for piping specified in JIS.

As shown in FIG. 6, when designing the piping system 41, route design (step S101) is first performed. In the route design, the piping route of the main pipe 15 and the piping route of each branch pipe 30 are set so that, for example, the piping length (design length) of the branch pipe 30 to each use point is shorter.

In the next step S102, usage prediction is performed. In the usage prediction, usage prediction information that predicts the amount of water used at each time is set for each use point. The usage prediction information is set based on usage information that is information regarding usage prediction of each use point. The usage information includes, for example, the purpose of water at each use point. In addition, in the usage prediction, the amount of water used by the piping system 41 as a whole is calculated for each time based on the usage prediction information of each use point, and the maximum and minimum usage amounts in the piping system 41 are calculated from the usage amount for each time. The usage amount is set.

In the next step S103, main pipe design is performed. In the main pipe design, based on the minimum usage amount and maximum usage amount of the piping system 41, the supply amount Q of the pump 13 and the main pipe are adjusted so that both the minimum flow rate and the maximum flow rate of the main pipe 15 fall within the corrosion suppression range where the corrosion rate is suppressed. The main pipe inner diameter A, which is the inner diameter of No. 15, is set. Note that the supply amount Q of the pump 13 referred to here is an amount that does not include the water returned to the tank 12 by the first bypass pipe 16. Moreover, the main pipe inner diameter A is a value based on the size of a stainless steel pipe for piping specified in JIS, that is, a value based on the nominal diameter and nominal thickness.

Specifically, the supply amount Q and main pipe inner diameter A of the pump 13 are the values obtained by dividing the maximum flow rate Qd1 obtained by subtracting the supply amount Q of the pump 13 by the minimum usage amount Qu1 by the flow path cross-sectional area S based on the main pipe inner diameter A. The maximum flow velocity v1 (=Qd1/S) is set to be smaller than the upper limit of the corrosion suppression range. In addition, the supply amount Q and the main pipe inner diameter A of the pump 13 are the minimum flow rate Qd2, which is the supply amount Q of the pump 13 subtracted by the maximum usage amount Qu2, divided by the flow passage cross-sectional area S based on the main pipe inner diameter A. The flow velocity v2 (=Qd2/S) is set to be larger than the lower limit of the corrosion suppression range. In addition, when the main pipe 15 is a stainless steel pipe for piping, the lower limit of the corrosion suppression range is 0.3 m/s, preferably 0.5 m/s, and the upper limit of the corrosion suppression range is 2.0 m/s, preferably is 1.5 m/s.

When the main pipe design (step S103) is completed, branch pipe design (step S104) is performed. In branch pipe design, an allowable value for the dead leg length of each branch pipe 30 is set.
In the branch pipe design, the flow rate at each time is calculated for the connection part 35 of each branch pipe 30 to the main pipe 15 based on usage prediction information of the use point located upstream of the connection part 35, and The minimum value of the flow rate for each time is calculated as the individual minimum flow rate. Then, based on the individual minimum flow rate, an individual minimum flow velocity v3, which is an individual minimum flow velocity, is calculated. The individual minimum flow velocity v3 increases as the connection portion 35 is located upstream of the main pipe 15 with respect to the supply source 11. The allowable value of the dead leg length of each branch pipe 30 is set based on the individual minimum flow velocity v3 calculated in this way and the above-mentioned evaluation result.

Specifically, for example, use point P located nth from the upstream side is defined as use point P(n). At this time, since the supply amount Q of the pump 13 flows into the connecting portion 35 corresponding to the use point P(1) located on the most upstream side when the on-off valve 42A is in the closed state, the supply amount Q of the pump 13 flows. The individual minimum flow velocity v3(1) is calculated by setting the individual minimum flow rate Qd3(1) to the individual minimum flow rate Qd3(1). This individual minimum flow velocity v3(1) is equal to the maximum flow velocity v1 of the piping system 41. That is, for the connection portion 35 corresponding to the use point P(1), the allowable value of the dead leg length is set by setting the maximum flow velocity v1 of the piping system 41 as the individual minimum flow velocity v3(1).

In addition, for the connection part 35 corresponding to the use point P(n) where n is 2 or more, the partial maximum usage Qu2 based on the usage prediction information from the use point P(1) to the use point (n-1) The value obtained by subtracting (1 to n-1) from the supply amount Q of the pump 13 is calculated as the individual minimum flow rate Qd3(n). Then, the allowable value of the dead leg length is set as the individual minimum flow rate v3(n), which is the value obtained by dividing the individual minimum flow rate Qd3 (n) by the flow path cross-sectional area S of the main pipe 15 (=Qd3(n)/S). Ru.

The allowable value of the dead leg length is such that the individual minimum flow velocity v3 increases as the connection portion 35 is located on the upstream side of the main pipe 15 with respect to the supply source 11. It is set to monotonically decrease toward the branch pipe 30. The monotonous decrease here means that the dead leg length of the branch pipe 30 located at the most upstream position is greater than the dead leg length of the branch pipe 30 located at the most downstream position, and the dead leg length of each branch pipe 30 is only one position upstream. This means that the length is equal to or less than the dead leg length of the branch pipe 30 located on the side.

When the branch pipe design (step S104) is completed, detailed specifications are set (step S105). In setting detailed specifications, the installation position of each valve, the installation position of a joint, partial piping length, etc. are set for the main pipe 15. Further, the size of each branch pipe 30 is set based on the pipe length and the allowable value of the dead leg length.

As shown in FIG. 5, in the piping system 41 designed through such a design procedure, a branch pipe 30 with a dead leg length of 6D is connected to the upstream portion 15a of the main pipe 15 with respect to the supply source 11, and the main pipe 15 A branch pipe 30 with a dead leg length of 4.5D is connected to the midstream portion 15b of the pipe. Further, a branch pipe 30 having a dead leg length of 3D is connected to the downstream portion 15c of the main pipe 15. Note that among the branch pipes 30, the branch pipe 30 located at the most upstream position with respect to the supply source 11 is the first branch pipe, and the branch pipe 30 located at the most downstream position with respect to the supply source 11 is the second branch pipe. It's a tube.

(Design support system)
As shown in FIG. 7, among the design procedures described above, usage prediction (step S102), main pipe design (step S103), and branch pipe design (step S104) can be realized by the design support system 45. The design support system 45 is mainly configured with a design support device 48. The design support system 45 includes a design support device 48, an input device 46 for inputting various information to the design support device 48, and a display device 47 capable of displaying various information output from the design support device 48. Ru.

The input device 46 is electrically connected to the design support device 48 via an input interface (not shown). The input device 46 includes, for example, a keyboard and a mouse, and is configured to allow a designer to input various information to the design support device 48. The designer inputs necessary information, for example, usage information necessary for the usage prediction in step S102, into the design support device 48 through the input device 46.

The display device 47 is electrically connected to the design support device 48 via an output interface (not shown). The display device 47 displays the results of processing executed by the design support device 48 and the like. An example of the content displayed by the display device 47 is a usage information input screen. Other examples of display contents by the display device 47 include pump information indicating the supply amount Q of the pump 13, main pipe information indicating the size of the main pipe 15, maximum flow velocity v1, minimum flow velocity v2, etc., and individual minimum flow velocity v3 of each branch pipe 30. and branch pipe information indicating the allowable value of dead leg length.

The design support device 48 may be configured as a circuit including one or more dedicated hardware circuits such as an ASIC, one or more processors operating according to a computer program (software), or a combination thereof. A processor includes a CPU and memory, such as RAM and ROM, where the memory stores program codes or instructions configured to cause the CPU to perform processing. Memory or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer.

The design support device 48 is a computer in which a piping system design support program stored in the medium 49 is installed. The design support device 48 includes a control section 50 and a storage section 51. The control unit 50 executes various processes based on information input via the input device 46, various information stored in the storage unit 51, and a design support program.

The control unit 50 includes an acquisition unit 52, a processing unit 53, and an output unit 54 as functional units that function by executing the design support program.
The acquisition unit 52 acquires various types of information input through the input device 46 and stores the acquired various information in a predetermined area of the storage unit 51.

The processing unit 53 executes various processes according to the various information stored in the storage unit 51 and the design support program.
The processing unit 53 displays a usage information input screen on the display device 47, and generates usage prediction information for each use point based on the usage information input through the input screen. The processing unit 53 sets the minimum usage amount and maximum usage amount in the piping system 41 based on the generated usage prediction information.

The processing unit 53 sets the supply amount Q of the pump 13 and the main pipe inner diameter A based on the minimum usage amount and maximum usage amount of the piping system 41. The processing unit 53 functions as a calculation unit and calculates the individual minimum flow velocity v3 for each use point.

The processing unit 53 functions as a tolerance value setting unit, and sets the tolerance value of the dead leg length based on the calculated individual minimum flow velocity v3. Regarding the allowable value of the dead leg length, the storage unit 51 stores, as one of various pieces of information, allowable value data that associates the individual minimum flow velocity v3 with the allowable value of the dead leg length. The allowable value data is a table based on the dead leg length evaluation results described above, and the allowable value of the dead leg length is defined for each individual minimum flow velocity v3 or for each range of the individual minimum flow velocity v3. The processing unit 53 sets an allowable value of the dead leg length for each branch pipe 30 by selecting a value corresponding to the individual minimum flow velocity v3 from the allowable value data.

The output unit 54 displays on the display device 47, in addition to the usage information input screen, pump information, main pipe information, branch pipe information, etc. that are design support results based on the usage information, in accordance with each process executed by the processing unit 53. . Based on the pump information, main pipe information, branch pipe information, etc. thus displayed on the display device 47, the designer determines detailed specifications of the piping system 41.

The operation and effects of this embodiment will be explained.
(1) In the present embodiment, the allowable value of the dead leg length is set based on the individual minimum flow velocity v3 at the connection portion 35 of the main pipe 15. Specifically, the larger the individual minimum flow velocity v3, the larger the allowable value of the dead leg length. According to such a configuration, the branch pipe inner diameter D can be set to a minimum value that satisfies the design length of the branch pipe 30 within the range of allowable values based on the individual minimum flow velocity v3. Thereby, the diameter of the branch pipe 30 can be reduced while satisfying the design length of the branch pipe 30. As a result, it is possible to suppress an increase in cost and a decrease in water quality caused by dead legs.

(2) In this embodiment, the dead leg length at which the concentration of colored water in the branch pipe 30 is 1/10 of the initial concentration was determined to be good. According to this configuration, even if the closing mechanism provided at the tip of the branch pipe 30 is in a closed state, it is possible to sufficiently suppress the accumulation of water in the branch pipe 30. As a result, deterioration in water quality caused by dead legs can be more effectively suppressed.

(3) In the present embodiment, the design support device 48 sets the allowable value of the dead leg length by selecting a value based on the individual minimum flow velocity v3 calculated for each branch pipe 30 from the allowable value data. According to such a configuration, the allowable value of the dead leg length can be set with a simple configuration.

(4) In this embodiment, the allowable value of the dead leg length is set so that it monotonically decreases from the upstream side with respect to the supply source 11. According to such a configuration, it is possible to reduce the diameter of the branch pipe 30 located upstream with respect to the supply source 11. As a result, it is possible to suppress an increase in cost and a decrease in water quality caused by dead legs.

This embodiment can be modified and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- In this embodiment, the dead leg length is based on the result of flowing colorless water through the connecting part 35 and branch pipe 30 of the main pipe 15 filled with colored water of a predetermined concentration and measuring the concentration of colored water after 60 seconds. Dead leg length was evaluated. The dead leg length is not limited to this, and the dead leg length may be evaluated based on, for example, the time required for the concentration of colored water in the branch pipe 30 to decrease to the target concentration after starting the flow of colorless water.

- In this embodiment, the dead leg length is based on the result of flowing colorless water through the connecting part 35 and branch pipe 30 of the main pipe 15 filled with colored water of a predetermined concentration and measuring the concentration of colored water after 60 seconds. Dead leg length was evaluated. The dead leg length is not limited to this, and the dead leg length may be evaluated based on the salt concentration, for example.

- In this embodiment, the dead leg length was evaluated through an experiment using the test piping system 10. The present invention is not limited to this, and the dead leg length may be evaluated using fluid analysis, or may be evaluated using both experiment and fluid analysis.

- In this embodiment, the processing unit 53 of the design support device 48, as a tolerance value setting unit, sets the tolerance value of the dead leg length based on the tolerance data stored in the storage unit 51. However, the present invention is not limited to this, and the processing unit 53 may set the allowable value of the dead leg length using an arithmetic expression using the individual minimum flow velocity v3 as a variable.

- In this embodiment, the design support device 48 was used to perform usage prediction (step S102), main pipe design (step S103), and branch pipe design (step S104). The configuration is not limited to this, and various calculations in the usage prediction, main pipe design, and branch pipe design may be performed by the designer. For example, the design support device 48 may be configured to be able to execute route design (step S101) by inputting the coordinate space where piping is possible, the installation coordinates of the pump 13, the installation coordinates of the use points, and the like.

- In this embodiment, in the test piping system 10, the branch pipe 30 is a pipe extending in a direction perpendicular to the extending direction of the main pipe 15. The branch pipe 30 is not limited to this, but may be a pipe bent at an acute angle θa with respect to the main pipe 15 as shown in FIG. 8(a), or may be bent with respect to the main pipe 15 as shown in FIG. 8(b). The pipe may be bent by an obtuse angle θb. Even with such a configuration, the dead leg length can be evaluated for each angle θ based on the evaluation method described above, and the allowable value of the dead leg length can be set based on the evaluation result. This dramatically improves the degree of freedom regarding the piping of the piping system. In addition, in the design support by the design support device 48, it is preferable that the angle θ of each branch pipe 30 is input and that tolerance value data for each angle θ is stored in the storage unit 51.

- The main pipe 15 and the branch pipes 30 are not limited to stainless steel pipes for piping, but may be metal pipes such as copper or aluminum pipes, or resin pipes such as vinyl chloride pipes.

DESCRIPTION OF SYMBOLS 10... Test piping system, 11... Supply source, 12... Tank, 13... Pump, 15... Main pipe, 15a... Upstream part, 15b... Midstream part, 15c... Downstream part, 16... First bypass pipe, 17... First Bypass valve, 20...Flow rate measurement section, 21...First flow rate measurement path, 22...Second flow rate measurement path, 23...First flow meter, 24...First regulating valve, 25...Second flow meter, 26...Second Regulating valve, 29... Test section, 30... Branch pipe, 31... First shutoff valve, 32... Second shutoff valve, 35... Connection portion, 36... Second bypass pipe, 37... Second bypass valve, 38... Drain pipe , 39... Drain valve, 40... Circulation valve, 41... Piping system, 42A... Open/close valve, 42B... Instrument, 43... Distribution control valve, 45... Design support system, 46... Input device, 47... Display device, 48... Design Support device, 49... Medium, 50... Control unit, 51... Storage unit, 52... Acquisition unit, 53... Processing unit, 54... Output unit.

Claims (5)

A method for designing a piping system comprising a main pipe through which water supplied by a supply source flows, and a plurality of branch pipes branching from the main pipe and having a closing mechanism at their tips, the method comprising:
When the dead leg length is the length from the center of the main pipe to the closing mechanism, which is expressed as a relative value to the inner diameter of the branch pipe,
For each of the plurality of branch pipes,
Based on the usage prediction of the piping system, determine the individual minimum flow rate of the water flowing through the connection portion of the branch pipe in the main pipe,
A method for designing a piping system, wherein an allowable value of the dead leg length is set according to the individual minimum flow velocity. A design support device for a piping system comprising a main pipe through which water supplied by a supply source flows, and a plurality of branch pipes branched from the main pipe and each having a closing mechanism at its tip,
When the dead leg length is the length from the center of the main pipe to the closing mechanism, which is expressed as a relative value to the inner diameter of the branch pipe,
The design support device includes:
a calculation unit that calculates, for each of the plurality of branch pipes, an individual minimum flow velocity of the water flowing through a connecting portion of the branch pipes in the main pipe, based on a usage prediction of the piping system;
A piping system design support device, comprising: a tolerance setting unit that sets a tolerance value for the dead leg length in accordance with the individual minimum flow velocity for each of the plurality of branch pipes. further comprising a storage unit storing tolerance value data in which the individual minimum flow velocity and the tolerance value are associated with each other;
The piping system design support device according to claim 2, wherein the tolerance value setting unit sets the tolerance value to a value selected from the tolerance data based on the individual minimum flow velocity. A design support device that supports the design of a piping system that includes a main pipe through which water supplied by a supply source flows and a plurality of branch pipes that branch from the main pipe and are provided with a closing mechanism at their tips,
When the dead leg length is the length from the center of the main pipe to the closing mechanism, which is expressed as a relative value to the inner diameter of the branch pipe,
For each of the plurality of branch pipes, a process of determining an individual minimum flow velocity of the water flowing through a connecting portion of the branch pipes in the main pipe based on a usage prediction of the piping system;
A program that causes each of the plurality of branch pipes to execute a process of setting an allowable value of the dead leg length according to the individual minimum flow velocity. A main pipe through which water supplied by the supply source flows;
A piping system comprising a plurality of branch pipes branching from the main pipe and each having a closing mechanism at its tip,
For each of the plurality of branch pipes, when the dead leg length is the length from the center of the main pipe to the closing mechanism and is expressed as a relative value to the inner diameter of the branch pipe,
Each of the plurality of branch pipes has a flow velocity determined for each of the plurality of branch pipes, and is based on a usage prediction of the piping system, and is determined according to an individual minimum flow velocity of the water flowing through the connection portion to the main pipe. The dead leg length is set below the allowable value,
In the piping system, the dead leg length monotonically decreases from the branch pipe located most upstream of the main pipe to the branch pipe located most downstream of the main pipe with respect to the supply source. .