Pressure and flow of gas through the pipeline. How to calculate pipe capacity for different systems - examples and rules
For safe and trouble-free operation of gas supply, it must be designed and calculated. It is important to perfectly select pipes for lines of all types of pressure, ensuring a stable supply of gas to the devices. In order for the selection of pipes, fittings and equipment to be as accurate as possible, a hydraulic calculation of the pipeline is carried out. How to make it? Admit it, you are not too knowledgeable in this matter, let's figure it out.
We offer you to get acquainted with scrupulously selected and thoroughly processed information on the options for the production of hydraulic calculations for gas pipeline systems. Using the data presented by us will ensure the supply of blue fuel with the required pressure parameters to the devices. Carefully verified data is based on the regulation of regulatory documentation.
The author of the article talks in detail about the principles and schemes for performing calculations. Gives an example of performing calculations. Graphical applications and video instructions are used as a useful informative addition.
Any hydraulic calculation performed is a determination of the parameters of the future gas pipeline. This procedure is mandatory and also one of the milestones preparation for construction. Whether the gas pipeline will operate in the optimal mode depends on the correctness of the calculation.
When performing each hydraulic calculation, the following is determined:
- the required pipe diameter, which will ensure efficient and stable transportation the right amount gas;
- whether pressure losses will be acceptable when moving the required volume of blue fuel in pipes of a given diameter.
Pressure losses occur due to the fact that in any gas pipeline there is hydraulic resistance. If calculated incorrectly, it can lead to the fact that consumers will not have enough gas for normal operation in all modes or at the moments of its maximum consumption.
This table is the result of a hydraulic calculation based on the given values. To perform calculations, you will need to enter specific indicators in the columns
Such an operation is a procedure standardized by the state, which is performed in accordance with the formulas and requirements set forth in SP 42-101-2003.
Calculations must be carried out by the builder. Data is taken as a basis specifications pipelines, which can be obtained in your city gas.
Gas pipelines requiring calculations
The state requires that hydraulic calculations be performed for all types of pipelines related to the gas supply system. Since the processes occurring during the movement of gas are always the same.
These pipelines include the following types:
- low pressure;
- medium, high pressure.
The first are designed to transport fuel to residential facilities, all kinds of public buildings, household enterprises. Moreover, in private apartment buildings, cottages, gas pressure should not exceed 3 kPa, at household enterprises (non-industrial) this figure is higher and reaches 5 kPa.
The second type of pipelines is designed to supply networks, and all kinds of low, medium pressure through gas control points, as well as supplying gas to individual consumers.
These can be industrial, agricultural, various utilities, and even detached or attached to industrial buildings. But in the last two cases there will be significant pressure limitations.
The types of gas pipelines listed above are conventionally divided by specialists into the following categories:
- intra-house, intrashop, that is, transporting blue fuel inside a building and delivering it to individual units, devices;
- subscriber branches used to supply gas from some distribution network to all available consumers;
- distribution used to supply gas to certain territories, for example, cities, their individual districts, industrial enterprises. Their configuration is different and depends on the features of the layout. The pressure inside the network can be any provided - low, medium, high.
In addition, hydraulic calculation is performed for gas networks with a different number of pressure stages, of which there are many varieties.
So, to meet the needs, two-stage networks can be used, working with gas transported at low, high pressure or low, medium. And also three-stage and various multi-stage networks have found application. That is, it all depends on the availability of consumers.
Hydraulic resistance is the main reason that it is necessary to carry out this species calculation. Moreover, it also depends on the material of the pipe.
Despite the wide variety of gas pipeline options, the hydraulic calculation is similar in any case. Since structural elements from similar materials are used for manufacturing, and the same processes occur inside the pipes.
Hydraulic resistance and its role
As mentioned above, the basis for the calculation is the presence of hydraulic resistance in each gas pipeline.
It acts on the entire pipeline structure, as well as on its individual parts, nodes - tees, places of a significant reduction in the diameter of pipes, stop valves, various valves. This results in a loss of pressure in the transported gas.
Hydraulic resistance is always the sum of:
- linear resistance, that is, acting along the entire length of the structure;
- local resistances acting at each component part of the structure, where there is a change in the speed of gas transportation.
These parameters constantly and significantly affect the performance of each gas pipeline. Therefore, as a result of an incorrect calculation, additional and impressive financial losses will occur due to the fact that the project will have to be redone.
Calculation rules
It was mentioned above that the procedure for any hydraulic calculation is regulated by the profile Code of Rules with the number 42-101-2003.
The document shows that the main way to perform the calculation is to use a computer for this purpose with special programs that allow you to calculate the planned pressure loss between sections of the future gas pipeline or the required pipe diameter.
Any hydraulic calculation is performed after creation design scheme, which includes the main indicators. Moreover, the user enters known data into the corresponding columns
If there are no such programs or a person believes that their use is inappropriate, then other methods allowed by the Code of Rules can be used. Which include:
- calculation according to the formulas given in the joint venture is the most hard way calculation;
- calculation according to the so-called nomograms is an easier option than using formulas, because you don’t have to make any calculations, because the necessary data are indicated in a special table and are given in the Code of Rules, and they just need to be selected.
Any of the calculation methods leads to the same results. Therefore, the newly constructed gas pipeline will be able to ensure timely, uninterrupted supply of the planned amount of fuel even during the hours of its maximum use.
PC calculation option
Performing a calculus using a computer is the least laborious - all that is required of a person is to insert the necessary data into the appropriate columns.
Therefore, a hydraulic calculation is done in a few minutes, and this operation does not require a large stock of knowledge, which is necessary when using formulas.
For his correct execution the following data must be taken from the technical specifications:
- gas density;
- coefficient of kinetic viscosity;
- gas temperature in your region.
The necessary technical conditions are obtained from the city gas department of the settlement where the gas pipeline will be built. Actually, the design of any pipeline begins with the receipt of this document, because it contains all the basic requirements for its design.
The use of special programs is the simplest method of hydraulic calculation, excluding the search and study of formulas for calculations.
Next, the developer needs to find out the gas consumption for each device that is planned to be connected to the gas pipeline. For example, if the fuel will be transported to a private house, then stoves for cooking are most often used there, all kinds of heating boilers, and in their passports there are always the right numbers.
In addition, you will need to know the number of burners for each stove that will be connected to the pipe.
At the next stage of collecting the necessary data, information is selected on the pressure drop at the installation sites of any equipment - this can be a meter, a cut-off valve, thermal shut-off valve, filter, other elements.
In this case, it is easy to find the necessary numbers - they are contained in a special table attached to the passport of each product. The designer should pay attention to the fact that the pressure drop at the maximum gas consumption should be indicated.
From a special table attached to the product passport, you can find out information about the pressure loss when connecting devices to the network
If the network will consist of several sections, then they must be numbered and indicate the actual length. In addition, for each, all variable indicators should be prescribed separately - this is the total flow rate of any device that will be used, the pressure drop, and other values.
AT without fail need a simultaneity factor. It takes into account the possibility joint work all gas consumers connected to the network. For example, total heating equipment located in an apartment building or a private house.
This data is used by the hydraulic calculation program to determine maximum load in any section or in the entire pipeline.
For each individual apartment or house, the specified coefficient does not need to be calculated, since its values are known and are indicated in the table below:
A table with simultaneity coefficients, the data from which is used in any type of calculation. It is enough to select the column corresponding to a particular household appliance, and take the desired number
If at some facility it is planned to use more than two heating boilers, furnaces, storage water heaters, then the simultaneity indicator will always be 0.85. Which will need to be indicated in the corresponding column used for the calculation of the program.
Next, you should specify the diameter of the pipes, and you will also need their roughness coefficients, which will be used in the construction of the pipeline. These values are standard and can be easily found in the Rulebook.
Influence of pipe material on the calculation
For the construction of gas pipelines, you can use pipes made only from certain materials: steel, polyethylene. In some cases, copper products are used. Metal-plastic structures will soon be widely used.
Each pipe has roughness, which results in a linear resistance that affects the process of gas movement. Moreover, this figure is much higher for steel products than for plastic ones.
Today, the necessary information can only be obtained for steel and polyethylene pipes. As a result, design and hydraulic calculation can only be performed taking into account their characteristics, which is required by the profile Code of Practice. And also in the document the data necessary for calculation are specified.
The roughness factor is always equated to the following values:
- for all polyethylene pipes, regardless of whether they are new or not, - 0.007 cm;
- for already used steel products - 0.1 cm;
- for new steel structures- 0.01 cm.
For any other types of pipes, this indicator is not indicated in the Code of Rules. Therefore, they should not be used for the construction of a new gas pipeline, since Gorgaz specialists may require adjustments. Again, this is an additional cost.
Calculation of flow in a limited area
If the gas pipeline consists of separate sections, then the calculation of the total flow rate for each of them will have to be performed separately. But this is not difficult, since the calculations will require already known numbers.
Defining data with a program
Knowing the initial indicators, having access to the simultaneity table and to the technical data sheets of stoves and boilers, you can proceed to the calculation. To do this, the following actions are performed (an example is given for an intra-house gas pipeline of precisely low pressure):
- The number of boilers is multiplied by the capacity of each of them.
- The resulting value is multiplied by the coefficient of simultaneity specified using a special table for this type of consumer.
- The number of stoves intended for cooking is multiplied by the performance of each of them.
- The value obtained after the previous operation is multiplied by the simultaneity factor taken from a special table.
- The amounts received for boilers and stoves are summed up.
Similar manipulations are carried out for all sections of the gas pipeline. The received data are entered into the corresponding columns of the program, with the help of which the calculations are performed. The electronics does everything else.
Calculation using formulas
This type of hydraulic calculation is similar to the one described above, that is, the same data will be required, but the procedure will be lengthy. Since everything will have to be done manually, in addition, the designer will need to perform a number of intermediate operations in order to use the obtained values for the final calculation.
And you will also have to devote a lot of time to understand many concepts, issues that a person does not meet when using a special program. The validity of the above can be seen by reading the formulas to be used.
Calculation using formulas is complex, therefore not accessible to everyone. The picture shows the formulas for calculating the pressure drop in the network of high, medium and low pressure and the coefficient of hydraulic friction
In the application of formulas, as in the case of hydraulic calculation using a special program, there are features for high, medium and, of course, low pressure gas pipelines. And it is worth remembering this, since a mistake is fraught, and always, with impressive financial costs.
Calculations using nomograms
Any special nomogram is a table where a number of values \u200b\u200bare indicated, by studying which you can get the desired indicators without performing calculations. In the case of hydraulic calculation - the diameter of the pipe and the thickness of its walls.
Nomograms for calculation are in a simple way receiving necessary information. It is enough to refer to the lines corresponding to the given characteristics of the network
There are separate nomograms for polyethylene and steel products. When calculating them, standard data were used, for example, the roughness of the inner walls. So you don't have to worry about the correctness of the information.
Calculation example
An example of performing a hydraulic calculation using a program for low-pressure gas pipelines is given. In the proposed table yellow all the data that the designer must enter himself are highlighted.
They are listed in the paragraph on computer hydraulic calculation above. These are gas temperature, coefficient of kinetic viscosity, density.
In this case, the calculation is carried out for boilers and stoves, in view of this, it is necessary to prescribe the exact number of burners, which can be 2 or 4. Accuracy is important, because the program will automatically select the simultaneity factor.
In the picture, columns are highlighted in yellow, in which the designer himself must enter the indicators. Below is the formula for calculating the flow rate on the site
It is worth paying attention to the numbering of sections - they do not come up with it on their own, but take it from a previously drawn up scheme, where similar numbers are indicated.
Next, the actual length of the gas pipeline and the so-called calculated length, which is longer, are prescribed. This happens because in all areas where there is local resistance, it is necessary to increase the length by 5-10%. This is done in order to exclude insufficient gas pressure from consumers. The program performs the calculation itself.
Total consumption in cubic meters, for which a separate column is provided, is calculated in advance for each section. If the house is an apartment building, then you need to indicate the number of housing, and starting from the maximum value, as can be seen in the corresponding column.
Without fail, all elements of the gas pipeline are entered in the table, during the passage of which pressure is lost. The example shows a thermal shut-off valve, a cut-off valve and a meter. The value of the loss in each case was taken in the product passport.
Using one program, you can make calculations for all types of gas pipelines. In the picture, calculations for a medium pressure network
The inner diameter of the pipe is indicated according to the terms of reference, if Gorgaz has any requirements, or from a previously drawn up diagram. In this case, in most areas it is prescribed in the amount of 5 cm, because most of the gas pipeline runs along the facade, and the local city gas company requires that the diameter be no less.
Even if you superficially familiarize yourself with the given example of performing a hydraulic calculation, it is easy to notice that, in addition to the values entered by a person, there are a large number of others. This is all the result of the program’s work, since after entering the numbers in specific columns highlighted in yellow, the calculation work for a person is completed.
That is, the calculation itself takes place quite quickly, after which the received data can be sent for approval to the city gas department of your city.
Conclusions and useful video on the topic
This video makes it possible to understand where the hydraulic calculation begins, where designers get the necessary data from:
The following video shows an example of one of the types of computer calculation:
To perform a hydraulic calculation using a computer, as the profile Code of Practice allows, it is enough to spend a little time getting acquainted with the program and collecting the necessary data. But practical value all this does not have, since drafting a project is a much more voluminous procedure and includes many other issues. In view of this, most citizens will have to seek help from specialists.
B.K. Kovalev, Deputy Director for R&D
AT recent times Increasingly, we come across examples when orders for industrial gas equipment are carried out by managers who do not have sufficient experience and technical knowledge in relation to the subject of procurement. Sometimes the result is not a completely correct application or a fundamentally incorrect selection of ordered equipment. One of the most common mistakes is the choice of nominal sections of the inlet and outlet pipelines of a gas distribution station, oriented only to the nominal values of gas pressure in the pipeline without taking into account the gas flow rate. The purpose of this article is to provide recommendations for determining bandwidth GDS pipelines, which allow, when choosing the standard size of a gas distribution station, to carry out a preliminary assessment of its performance for specific values of operating pressures and nominal diameters of the inlet and outlet pipelines.
When choosing the required standard sizes of GDS equipment, one of the main criteria is performance, which largely depends on the capacity of the inlet and outlet pipelines.
The capacity of pipelines of a gas distribution station is calculated taking into account the requirements normative documents limiting the maximum allowable gas flow rate in the pipeline to 25m/s. In turn, the gas flow rate depends mainly on the pressure of the gas and the cross-sectional area of the pipeline, as well as on the compressibility of the gas and its temperature.
The capacity of the pipeline can be calculated from the classical formula for the velocity of gas in a gas pipeline (Design Guide main gas pipelines edited by A.K. Dertsakyan, 1977):
where W- speed of gas movement in the gas pipeline, m/s;
Q- gas flow through a given section (at 20 ° C and 760 mm Hg), m 3 / h;
z- compressibility factor (for an ideal gas z = 1);
T = (273 + t °C)- gas temperature, °K;
D- internal diameter of the pipeline, cm;
p\u003d (Prab + 1.033) - absolute gas pressure, kgf / cm 2 (atm);
In the SI system (1 kgf / cm 2 \u003d 0.098 MPa; 1 mm \u003d 0.1 cm), this formula will take the following form:
where D is the inner diameter of the pipeline, mm;
p = (Pwork + 0.1012) - absolute gas pressure, MPa.
It follows that the capacity of the pipeline Qmax, corresponding to the maximum gas flow rate w = 25m/s, is determined by the formula:
For preliminary calculations, we can take z = 1; T \u003d 20? C \u003d 293? K and, with a sufficient degree of reliability, carry out calculations using a simplified formula:
The values of the throughput capacity of pipelines with the most common conditional diameters in GDS at various values gas pressures are given in table 1.
| Working (MPa) | Pipeline capacity (m?/h), at wgas=25 m/s; z = 1; T \u003d 20? C \u003d 293? K |
|||||||
|---|---|---|---|---|---|---|---|---|
| DN 50 | DN 80 | DN 100 | DN 150 | DN 200 | DN 300 | DN 400 | DN 500 | |
Note: for a preliminary assessment of the throughput of pipelines, the internal diameters of the pipes are taken equal to their conventional values (DN 50; 80; 100; 150; 200; 300; 400; 500).
Examples of using the table:
1. Determine the capacity of the GDS with DNin=100mm, DNout=150mm, with PNin=2.5 - 5.5 MPa and PNout=1.2 MPa.
From table 1 we find that the capacity of the outlet pipeline DN=150mm at PN=1.2 MPa will be 19595 m 3 / h, at the same time the inlet pipeline DN=100 mm at PN=5.5 MPa will be able to pass 37520 m 3 / h , and at PN=2.5 MPa - only 17420 m 3 / h. Thus, this GDS with PNin=2.5 - 5.5 MPa and PNout=1.2 MPa will be able to pass from 17420 to 19595 m 3 /h as much as possible. Note: more exact values Qmax can be obtained from formula (3).
2. Determine the diameter of the outlet pipeline of the GDS, with a capacity of 5000 m 3 / h at Pin=3.5 MPa for outlet pressures Pout1=1.2 MPa and Pout2=0.3 MPa.
From table 1 we find that a throughput of 5000m 3 /hour at Pout=1.2 MPa will be provided by a pipeline DN=80mm, and at Pout=0.3 MPa - only DN=150mm. At the same time, it is enough to have a pipeline DN=50mm at the GDS inlet.
Added: 02/13/2017
The construction of a swimming reservoir is always accompanied by the laying of pipelines and the installation of embedded elements, such as return nozzles, bottom intakes, skimmers ... If the diameter of the pipes is less than necessary, the intake and supply of water will occur with increased friction losses, which will cause the pump to experience loads, capable of destroying it. If the pipes are laid with a diameter greater than the required one, the costs for the construction of the reservoir are unreasonably increased.
How to choose the right pipe diameter?
How to choose the right pipe diameter?
Return nozzles, bottom intakes, skimmers, each have a hole for connecting a certain diameter, which initially determines the diameter of the pipes. Usually these connections are 1 1/2" - 2" to which a pipe with a diameter of 50 mm is connected. If several annealed elements are connected in one line, then the common pipe must be of a larger diameter than the pipes suitable for it.
The choice of pipe is also influenced by the performance of the pump, which determines the speed and amount of water pumped.
The throughput of pipes of various diameters can be determined from the following table:
Throughput of pipes of various diameters.
| Diameter, mm | Int. area section, mm 2 | Throughput in m 3 /h at speed | |||||
| Outer | Interior | 0.5 m/s | 0.8 m/s | 1.2 m/s | 2.0 m/s | 2.5 m/s | |
| 16 | 10 | 79 | 0,14 | 0,23 | 0,34 | 0,57 | 0,71 |
| 20 | 15 | 177 | 0,32 | 0,51 | 0,76 | 1,27 | 1,59 |
| 25 | 20 | 314 | 0,91 | 1,36 | 2,26 | 2,83 | |
| 32 | 25 | 491 | 0,88 | 1,41 | 2,12 | 3,54 | 4,42 |
| 40 | 32 | 805 | 1,45 | 2,32 | 3,48 | 5,79 | 7,24 |
| 50 | 40 | 1257 | 2,26 | 3,62 | 5,43 | 9,05 | 11,31 |
| 63 | 50 | 1964 | 3,54 | 5,66 | 8,49 | 14,14 | 17,68 |
| 75 | 65 | 3319 | 5,97 | 9,56 | 14,34 | 23,90 | 29,87 |
| 90 | 80 | 5028 | 9,05 | 14,48 | 21,72 | 36,20 | 45,25 |
| 110 | 100 | 7857 | 14,14 | 22,63 | 33,94 | 56,57 | 70,71 |
| 125 | 110 | 9506 | 17,11 | 27,38 | 41,07 | 68,45 | 85,56 |
| 140 | 125 | 12276 | 22,10 | 35,35 | 53,03 | 88,39 | 110,48 |
| 160 | 150 | 17677 | 31,82 | 50,91 | 76,37 | 127,28 | 159,09 |
| 200 | 175 | 24061 | 43,31 | 69,29 | 103,94 | 173,24 | 216,54 |
| 225 | 200 | 31426 | 56,57 | 90,51 | 135,76 | 226,27 | 282,83 |
| 250 | 225 | 39774 | 71,59 | 114,55 | 171,82 | 286,37 | 357,96 |
| 315 | 300 | 70709 | 127,28 | 203,64 | 305,46 | 509,10 | 636,38 |
To select the diameter of the turbo, we need to know the following values:
Let's consider the technology of pipe selection on specific examples of tying embedded elements.
Pipe diameter for connecting return nozzles.
For example, the movement of water in the system is provided by a pump, maximum performance 16 m 3 / hour. The return of water to the swimming bowl is carried out through 4 return nozzles - (connection 2 " external thread), each screwed in with a D 50/63 connection. The nozzles are arranged in pairs on opposite sides. We will select the necessary pipeline.
The speed of water on the supply line is 2 m/s. The nozzles are divided into two branches of two pieces. Productivity for each nozzle - 4 m 3 /hour, for each branch - 8 m 3 /hour. We will select the diameter of the common pipe, pipes for each branch and turbos for each nozzle. If the table does not contain an exact match of performance for a specific flow rate, we take the closest one. The table gives:
- with a capacity of 16 m 3 / h (in the table, the nearest value is 14.14 m 3 / h) - the pipe diameter is 63 mm;
- with a capacity of 8 m 3 / h (in the table, the nearest value is 9.05 m 3 / h) - the diameter of the turbine is 50 mm;
- with a capacity of 4 m3 / h (in the table, the nearest value is 3.54 m 3 / h) - the pipe diameter is 32 mm.
It turns out that a pipe with a diameter of 63 mm is suitable for the general supply, for each branch - with a diameter of 50 mm, and for each nozzle - with a diameter of 32 mm. But since the wall passage is designed to connect pipes 50 and 63, we don’t take a pipe with a diameter of 32 mm, but connect everything with a 50 mm pipe. The 63rd pipe goes to the tee, the wiring is the 50th pipe.
Diameter of pipes for connecting skimmers.
The same pump with a capacity of 16 m 3 /hour takes water through the skimmers. in filtration mode, it usually takes from 70 to 90% of the water from the total flow that the pump sucks in, the rest falls on the bottom drain. In our case, 70% of productivity is 11.2 m 3 / hour. Skimmer connection is usually 1 1/2" or 2". The flow rate on the suction line of the pump is 1.2 m/s.
According to the table we get:
- for this case, a pipe with a diameter of 63 mm is sufficient, but ideally - 75 mm;
- in the case of connecting two skimmers, we branch out with the 50th pipe.
The diameter of the pipes for connecting the bottom intake.
30% of the output of the EcoX2 16000 pump is 4.8 m 3 /hour. According to the table, a 50 mm pipe is enough to connect the bottom drain. Usually, when connecting the bottom drain, they are guided by the diameter of its connection. The standard one has a 2" connection, so a 63 mm pipe is chosen.
Calculation of pipe diameter.
The formula for calculating the optimal diameter of the pipeline is obtained from the formula for the flow rate:
Q - flow rate of pumped water, m 3 / s
d - pipeline diameter, m
v - flow velocity, m/s
P - pi = 3.14
Hence, the calculation formula for the optimal diameter of the pipeline:
d=((4*Q)/(P*v)) 1/2
Let's pay attention to the fact that in this formula the flow rate of pumped water is expressed in m 3 / s. The performance of pumps is usually indicated in m 3 / hour. In order to convert m 3 / h to m 3 / s, you need to divide the value by 3600.
Q (m 3 / s) \u003d Q (m 3 / hour) / 3600
As an example, we calculate the optimal pipeline diameter for a pump capacity of 16 m 3 / h on the supply line.
Let's translate the performance in m 3 / s:
Q (m 3 / s) \u003d 16 m 3 / hour / 3600 \u003d 0.0044 m 3 / s
The flow velocity on the supply line is 2 m/s.
Substituting the values into the formula, we get:
d=((4*0.0044)/(3.14*2)) 1/2 ≈0.053 (m) = 53 (mm)
It turned out that in this case the optimal inner diameter of the pipe will be equal to 53 mm. Compare with the table: for the nearest productivity of 14.14 m 3 / h at a flow rate of 2 m / s, a pipe with an internal diameter of 50 mm is suitable.
When selecting pipes, you can use one of the methods described above, we have confirmed their equivalence by calculations.
Based on materials from sites: waterspace com, ence-pumps ru
Laying a pipeline is not very difficult, but rather troublesome. One of the most difficult problems this is the calculation of the throughput of the pipe, which directly affects the efficiency and performance of the structure. In this article, we will talk about how the throughput of a pipe is calculated.
throughput is one of key indicators any pipe. Despite this, this indicator is rarely indicated in the marking of the pipe, and there is little sense in this, because the throughput depends not only on the dimensions of the product, but also on the design of the pipeline. That is why this indicator has to be calculated independently.
Methods for calculating the throughput of the pipeline
- External diameter. This indicator is expressed in the distance from one side of the outer wall to the other side. In calculations, this parameter has the designation Day. The outside diameter of the pipes is always shown on the label.
- Nominal diameter. This value is defined as the diameter of the internal section, which is rounded to whole numbers. When calculating, the value of the conditional passage is displayed as Du.
Calculation of pipe patency can be carried out according to one of the methods, which must be chosen depending on the specific conditions for laying the pipeline:
- Physical calculations. In this case, the pipe capacity formula is used, which allows taking into account each design indicator. The choice of formula is influenced by the type and purpose of the pipeline - for example, for sewer systems has its own set of formulas, as for other types of structures.
- Tabular Calculations. Pick up optimal value patency can be using a table with approximate values, which is most often used for arranging wiring in an apartment. The values indicated in the table are rather blurry, but this does not prevent them from being used in calculations. The only drawback of the tabular method is that it calculates the capacity of the pipe depending on the diameter, but does not take into account changes in the latter due to deposits, therefore, for lines prone to build-up, such a calculation will not the best choice. To get accurate results, you can use the Shevelev table, which takes into account almost all factors affecting pipes. Such a table is great for the installation of highways on separate land plots.
- Calculation using programs. Many companies specializing in the laying of pipelines use in their activities computer programs, allowing you to accurately calculate not only the throughput of pipes, but also a lot of other indicators. For independent calculations, you can use online calculators, which, although they have a slightly larger error, are available at free mode. good option a large shareware program is "TAScope", and in the domestic space the most popular is "Hydrosystem", which also takes into account the nuances of installing pipelines depending on the region.
Calculation of the throughput capacity of gas pipelines
The design of a gas pipeline requires a sufficiently high accuracy - the gas has a very large ratio compression, due to which leaks are possible even through microcracks, not to mention serious breaks. That is why the correct calculation of the throughput of the pipe through which the gas will be transported is very important.
If we are talking about gas transportation, then the throughput of pipelines, depending on the diameter, will be calculated according to the following formula:
- Qmax = 0.67 DN2 * p,
Where p is the value of the working pressure in the pipeline, to which 0.10 MPa is added;
Du - the value of the conditional passage of the pipe.
The above formula for calculating the throughput of a pipe by diameter allows you to create a system that will work in a domestic environment.
In industrial construction and when performing professional calculations, a different type of formula is used:
- Qmax \u003d 196.386 Du2 * p / z * T,
Where z is the compression ratio of the transported medium;
T is the temperature of the transported gas (K).
To avoid problems, when calculating the pipeline, professionals also have to take into account the climatic conditions in the region where it will pass. If a outside diameter pipe is less than the gas pressure in the system, then the pipeline is very likely to be damaged during operation, resulting in the loss of the transported substance and an increased risk of explosion in the weakened pipe section.
If necessary, it is possible to determine the permeability of a gas pipe using a table that describes the relationship between the most common pipe diameters and the working pressure level in them. By and large, the tables have the same drawback that the throughput of the pipeline calculated by the diameter has, namely, the inability to take into account the impact of external factors.
Calculation of the capacity of sewer pipes
When designing a sewer system, it is imperative to calculate the throughput of the pipeline, which directly depends on its type (sewer systems are pressure and non-pressure). Hydraulic laws are used to carry out calculations. The calculations themselves can be carried out both using formulas and using the corresponding tables.
For the hydraulic calculation of the sewer system, the following indicators are required:
- Pipe diameter - Du;
- The average speed of movement of substances - v;
- The value of the hydraulic slope - I;
- Degree of filling – h/DN.
As a rule, only the last two parameters are calculated during calculations - the rest after that can be determined without any problems. The amount of hydraulic slope is usually equal to the slope of the ground, which will allow the flow of water to move at the speed necessary for the system to self-clean.
The speed and maximum filling level of domestic sewage are determined by the table, which can be written as follows:
- 150-250 mm - h / DN is 0.6, and the speed is 0.7 m / s.
- Diameter 300-400 mm - h / DN is 0.7, speed - 0.8 m / s.
- Diameter 450-500 mm - h / DN is 0.75, speed - 0.9 m / s.
- Diameter 600-800 mm - h / DN is 0.75, speed - 1 m / s.
- Diameter 900+ mm - h / DN is 0.8, speed - 1.15 m / s.
For a product with a small cross section, there are normative indicators minimum slope of the pipeline:
- With a diameter of 150 mm, the slope should not be less than 0.008 mm;
- With a diameter of 200 mm, the slope should not be less than 0.007 mm.
The following formula is used to calculate the volume of wastewater:
- q = a*v,
Where a is the free area of the flow;
v is the speed of effluent transportation.
The rate of transport of a substance can be determined using the following formula:
- v=C√R*i,
where R is the value of the hydraulic radius,
C is the wetting coefficient;
i - the degree of slope of the structure.
From the previous formula, the following can be deduced, which will allow you to determine the value of the hydraulic slope:
- i=v2/C2*R.
To calculate the wetting coefficient, a formula of the following form is used:
- С=(1/n)*R1/6,
Where n is a coefficient that takes into account the degree of roughness, which varies from 0.012 to 0.015 (depending on the pipe material).
The R value is usually equated to the usual radius, but this is only relevant if the pipe is completely filled.
For other situations, a simple formula is used:
- R=A/P
Where A is the cross-sectional area of the water flow,
P is the length of the inner part of the pipe that is in direct contact with the liquid.
Tabular calculation of sewer pipes
It is also possible to determine the patency of the pipes of the sewer system using tables, and the calculations will directly depend on the type of system:
- Non-pressure sewerage. To calculate non-pressure sewer systems, tables are used that contain all required indicators. Knowing the diameter of the pipes to be installed, you can select all other parameters depending on it and substitute them into the formula (read also: ""). In addition, the table indicates the volume of liquid passing through the pipe, which always coincides with the pipeline's permeability. If necessary, you can use the Lukin tables, which indicate the throughput of all pipes with a diameter in the range from 50 to 2000 mm.
- Pressure sewer. Determine throughput in this type systems through tables are somewhat simpler - it is enough to know the maximum degree of filling of the pipeline and the average speed of liquid transportation. See also: "".
Bandwidth table polypropylene pipes allows you to find out all the parameters necessary for arranging the system.
Calculation of the capacity of the water supply
Water pipes in private construction are used most often. In any case, the water supply system has a serious load, so the calculation of the throughput of the pipeline is mandatory, because it allows you to create the maximum comfortable conditions operation of the future structure.
To determine the patency water pipes you can use their diameter (read also: ""). Of course, this indicator is not the basis for calculating the patency, but its influence cannot be ruled out. The increase in the inner diameter of the pipe is directly proportional to its permeability - that is, a thick pipe almost does not impede the movement of water and is less susceptible to the accumulation of various deposits.
However, there are other indicators that also need to be taken into account. For example, a very important factor is the coefficient of fluid friction about inner part pipes (for different materials have eigenvalues). It is also worth considering the length of the entire pipeline and the pressure difference at the beginning of the system and at the outlet. An important parameter is the number of different adapters present in the design of the water supply system.
The throughput of polypropylene water pipes can be calculated depending on several parameters using the tabular method. One of them is a calculation in which the main indicator is the temperature of the water. As the temperature rises, the liquid expands in the system, so friction increases. To determine the patency of the pipeline, you need to use the appropriate table. There is also a table that allows you to determine the patency in the pipes depending on the water pressure.
The most accurate calculation of water according to the throughput of the pipe is made possible by the Shevelev tables. In addition to accuracy and a large number standard values, in these tables there are formulas that allow you to calculate any system. This material fully describes all situations related to hydraulic calculations, therefore, most professionals in this field most often use the Shevelev tables.
The main parameters taken into account in these tables are:
- External and internal diameters;
- Pipeline wall thickness;
- The period of operation of the system;
- The total length of the highway;
- Functional purpose of the system.
Conclusion
Pipe capacity calculation can be performed different ways. Choice best way calculation depends on a large number of factors - from the size of the pipes to the purpose and type of system. In each case, there are more and less accurate calculation options, so both a professional specializing in laying pipelines and an owner who decides to independently lay a highway at home will be able to find the right one.
throughput - important parameter for any pipes, channels and other heirs of the Roman aqueduct. However, the throughput is not always indicated on the pipe packaging (or on the product itself). In addition, it also depends on the pipeline scheme how much liquid the pipe passes through the section. How to correctly calculate the throughput of pipelines?
Methods for calculating the throughput of pipelines
There are several methods for calculating this parameter, each of which is suitable for a particular case. Some notations that are important in determining the throughput of a pipe:
Outer diameter - the physical size of the pipe section from one edge of the outer wall to the other. In calculations, it is designated as Dn or Dn. This parameter is indicated in the marking.
Nominal diameter is the approximate value of the diameter of the internal section of the pipe, rounded up to a whole number. In calculations, it is designated as Du or Du.
Physical methods for calculating the throughput of pipes
Pipe throughput values are determined by special formulas. For each type of product - for gas, water supply, sewerage - the methods of calculation are different.
Tabular calculation methods
There is a table of approximate values \u200b\u200bcreated to facilitate the determination of the throughput of pipes for intra-apartment wiring. In most cases, high precision is not required, so the values can be applied without complex calculations. But this table does not take into account the decrease in throughput due to the appearance of sedimentary growths inside the pipe, which is typical for old highways.
| Liquid type | Speed (m/s) |
| City water supply | 0,60-1,50 |
| Water pipeline | 1,50-3,00 |
| Central heating water | 2,00-3,00 |
| Water pressure system in the pipeline line | 0,75-1,50 |
| hydraulic fluid | up to 12m/s |
| Oil pipeline line | 3,00-7,5 |
| Oil in the pressure system of the pipeline line | 0,75-1,25 |
| Steam in the heating system | 20,0-30,00 |
| Steam central pipeline system | 30,0-50,0 |
| Steam in a high temperature heating system | 50,0-70,00 |
| Air and gas in central system pipeline | 20,0-75,00 |
There is an exact capacity calculation table, called the Shevelev table, which takes into account the pipe material and many other factors. These tables are rarely used when laying water pipes around the apartment, but in a private house with several non-standard risers they can come in handy.
Calculation using programs
At the disposal of modern plumbing firms there are special computer programs for calculating the throughput of pipes, as well as many other similar parameters. In addition, online calculators have been developed that, although less accurate, are free and do not require installation on a PC. One of the stationary programs "TAScope" is a creation of Western engineers, which is shareware. Large companies use "Hydrosystem" - this is a domestic program that calculates pipes according to criteria that affect their operation in the regions of the Russian Federation. In addition to hydraulic calculation, it allows you to calculate other parameters of pipelines. average price 150,000 rubles.
How to calculate the throughput of a gas pipe
Gas is one of the most difficult materials to transport, in particular because it tends to compress and therefore can flow through the smallest gaps in pipes. To the calculation of throughput gas pipes(similar to design gas system in general) have special requirements.
The formula for calculating the throughput of a gas pipe
The maximum capacity of gas pipelines is determined by the formula:
Qmax = 0.67 DN2 * p
where p is equal to the working pressure in the gas pipeline system + 0.10 MPa or the absolute pressure of the gas;
Du - conditional passage of the pipe.
There is a complex formula for calculating the throughput of a gas pipe. When carrying out preliminary calculations, as well as when calculating a domestic gas pipeline, it is usually not used.
Qmax = 196.386 Du2 * p/z*T
where z is the compressibility factor;
T is the temperature of the transported gas, K;
According to this formula, the direct dependence of the temperature of the transported medium on pressure is determined. The higher the T value, the more the gas expands and presses against the walls. Therefore, when calculating large highways, engineers take into account possible weather in the area where the pipeline passes. If the nominal value of the pipe DN is less than the pressure of the gas formed during high temperatures in summer (for example, at +38 ... +45 degrees Celsius), then damage to the line is likely. This entails the leakage of valuable raw materials, and creates the possibility of an explosion of the pipe section.
Table of capacities of gas pipes depending on pressure
There is a table for calculating the throughput of a gas pipeline for commonly used diameters and nominal working pressure of pipes. To determine the characteristics of a gas line of non-standard sizes and pressure, you will need engineering calculations. Also, the pressure, speed of movement and volume of gas is affected by the temperature of the outside air.
The maximum velocity (W) of the gas in the table is 25 m/s and z (compressibility factor) is 1. The temperature (T) is 20 degrees Celsius or 293 Kelvin.
| Pwork(MPa) | Throughput capacity of the pipeline (m? / h), with wgas \u003d 25m / s; z \u003d 1; T \u003d 20? C = 293? K | |||||||
|---|---|---|---|---|---|---|---|---|
| DN 50 | DN 80 | DN 100 | DN 150 | DN 200 | DN 300 | DN 400 | DN 500 | |
| 0,3 | 670 | 1715 | 2680 | 6030 | 10720 | 24120 | 42880 | 67000 |
| 0,6 | 1170 | 3000 | 4690 | 10550 | 18760 | 42210 | 75040 | 117000 |
| 1,2 | 2175 | 5570 | 8710 | 19595 | 34840 | 78390 | 139360 | 217500 |
| 1,6 | 2845 | 7290 | 11390 | 25625 | 45560 | 102510 | 182240 | 284500 |
| 2,5 | 4355 | 11145 | 17420 | 39195 | 69680 | 156780 | 278720 | 435500 |
| 3,5 | 6030 | 15435 | 24120 | 54270 | 96480 | 217080 | 385920 | 603000 |
| 5,5 | 9380 | 24010 | 37520 | 84420 | 150080 | 337680 | 600320 | 938000 |
| 7,5 | 12730 | 32585 | 50920 | 114570 | 203680 | 458280 | 814720 | 1273000 |
| 10,0 | 16915 | 43305 | 67670 | 152255 | 270680 | 609030 | 108720 | 1691500 |
Capacity of the sewer pipe
Bandwidth sewer pipe- an important parameter that depends on the type of pipeline (pressure or non-pressure). The calculation formula is based on the laws of hydraulics. In addition to the laborious calculation, tables are used to determine the capacity of the sewer.
For the hydraulic calculation of sewerage, it is required to determine the unknowns:
- pipeline diameter Du;
- average flow velocity v;
- hydraulic slope l;
- degree of filling h / Du (in calculations, they are repelled from the hydraulic radius, which is associated with this value).
In practice, they are limited to calculating the value of l or h / d, since the remaining parameters are easy to calculate. hydraulic slope in preliminary calculations It is considered to be equal to the slope of the earth's surface, at which the movement of wastewater will not be lower than the self-cleaning speed. The speed values as well as the maximum h/Dn values for residential networks can be found in Table 3.
Yulia Petrichenko, expert
In addition, there is a normalized value for the minimum slope for pipes with a small diameter: 150 mm
(i=0.008) and 200 (i=0.007) mm.
The formula for the volumetric flow rate of a liquid looks like this:
where a is the free area of the flow,
v is the flow velocity, m/s.
The speed is calculated by the formula:
where R is the hydraulic radius;
C is the wetting coefficient;
From this we can derive the formula for the hydraulic slope:
According to it, this parameter is determined if calculation is necessary.
where n is the roughness factor, ranging from 0.012 to 0.015 depending on the pipe material.
The hydraulic radius is considered equal to the usual radius, but only when the pipe is completely filled. In other cases, use the formula:
where A is the area of the transverse fluid flow,
P - wetted perimeter, or transverse length inner surface pipe that touches the liquid.
Capacity tables for non-pressure sewer pipes
The table takes into account all the parameters used to perform the hydraulic calculation. The data is selected according to the value of the pipe diameter and substituted into the formula. Here, the volumetric flow rate q of the liquid passing through the pipe section has already been calculated, which can be taken as the throughput of the pipeline.
In addition, there are more detailed Lukin tables containing ready-made throughput values for pipes of different diameters from 50 to 2000 mm.
Capacity tables for pressurized sewer systems
In the capacity tables for sewer pressure pipes, the values depend on the maximum degree of filling and the calculated average velocity waste water.
| Diameter, mm | Filling | Acceptable (optimal slope) | The speed of movement of waste water in the pipe, m / s | Consumption, l / s |
| 100 | 0,6 | 0,02 | 0,94 | 4,6 |
| 125 | 0,6 | 0,016 | 0,97 | 7,5 |
| 150 | 0,6 | 0,013 | 1,00 | 11,1 |
| 200 | 0,6 | 0,01 | 1,05 | 20,7 |
| 250 | 0,6 | 0,008 | 1,09 | 33,6 |
| 300 | 0,7 | 0,0067 | 1,18 | 62,1 |
| 350 | 0,7 | 0,0057 | 1,21 | 86,7 |
| 400 | 0,7 | 0,0050 | 1,23 | 115,9 |
| 450 | 0,7 | 0,0044 | 1,26 | 149,4 |
| 500 | 0,7 | 0,0040 | 1,28 | 187,9 |
| 600 | 0,7 | 0,0033 | 1,32 | 278,6 |
| 800 | 0,7 | 0,0025 | 1,38 | 520,0 |
| 1000 | 0,7 | 0,0020 | 1,43 | 842,0 |
| 1200 | 0,7 | 0,00176 | 1,48 | 1250,0 |
Capacity of the water pipe
Water pipes in the house are used most often. And since they are under a heavy load, then the calculation of the throughput of the water main becomes important condition reliable operation.
Passability of the pipe depending on the diameter
Diameter is not the most important parameter when calculating pipe patency, but it also affects its value. The larger the inner diameter of the pipe, the higher the permeability, as well as the lower the chance of blockages and plugs. However, in addition to the diameter, it is necessary to take into account the coefficient of friction of water on the pipe walls (table value for each material), the length of the line and the difference in fluid pressure at the inlet and outlet. In addition, the number of bends and fittings in the pipeline will greatly affect the patency.
Table of pipe capacity by coolant temperature
The higher the temperature in the pipe, the lower its capacity, as the water expands and thus creates additional friction. For plumbing, this is not important, but in heating systems is the key parameter.
There is a table for calculations of heat and coolant.
| Pipe diameter, mm | Bandwidth | |||
|---|---|---|---|---|
| By warmth | By coolant | |||
| Water | Steam | Water | Steam | |
| Gcal/h | t/h | |||
| 15 | 0,011 | 0,005 | 0,182 | 0,009 |
| 25 | 0,039 | 0,018 | 0,650 | 0,033 |
| 38 | 0,11 | 0,05 | 1,82 | 0,091 |
| 50 | 0,24 | 0,11 | 4,00 | 0,20 |
| 75 | 0,72 | 0,33 | 12,0 | 0,60 |
| 100 | 1,51 | 0,69 | 25,0 | 1,25 |
| 125 | 2,70 | 1,24 | 45,0 | 2,25 |
| 150 | 4,36 | 2,00 | 72,8 | 3,64 |
| 200 | 9,23 | 4,24 | 154 | 7,70 |
| 250 | 16,6 | 7,60 | 276 | 13,8 |
| 300 | 26,6 | 12,2 | 444 | 22,2 |
| 350 | 40,3 | 18,5 | 672 | 33,6 |
| 400 | 56,5 | 26,0 | 940 | 47,0 |
| 450 | 68,3 | 36,0 | 1310 | 65,5 |
| 500 | 103 | 47,4 | 1730 | 86,5 |
| 600 | 167 | 76,5 | 2780 | 139 |
| 700 | 250 | 115 | 4160 | 208 |
| 800 | 354 | 162 | 5900 | 295 |
| 900 | 633 | 291 | 10500 | 525 |
| 1000 | 1020 | 470 | 17100 | 855 |
Pipe capacity table depending on the coolant pressure
There is a table describing the throughput of pipes depending on the pressure.
| Consumption | Bandwidth | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| DN pipe | 15 mm | 20 mm | 25 mm | 32 mm | 40 mm | 50 mm | 65 mm | 80 mm | 100 mm |
| Pa/m - mbar/m | less than 0.15 m/s | 0.15 m/s | 0.3 m/s | ||||||
| 90,0 - 0,900 | 173 | 403 | 745 | 1627 | 2488 | 4716 | 9612 | 14940 | 30240 |
| 92,5 - 0,925 | 176 | 407 | 756 | 1652 | 2524 | 4788 | 9756 | 15156 | 30672 |
| 95,0 - 0,950 | 176 | 414 | 767 | 1678 | 2560 | 4860 | 9900 | 15372 | 31104 |
| 97,5 - 0,975 | 180 | 421 | 778 | 1699 | 2596 | 4932 | 10044 | 15552 | 31500 |
| 100,0 - 1,000 | 184 | 425 | 788 | 1724 | 2632 | 5004 | 10152 | 15768 | 31932 |
| 120,0 - 1,200 | 202 | 472 | 871 | 1897 | 2898 | 5508 | 11196 | 17352 | 35100 |
| 140,0 - 1,400 | 220 | 511 | 943 | 2059 | 3143 | 5976 | 12132 | 18792 | 38160 |
| 160,0 - 1,600 | 234 | 547 | 1015 | 2210 | 3373 | 6408 | 12996 | 20160 | 40680 |
| 180,0 - 1,800 | 252 | 583 | 1080 | 2354 | 3589 | 6804 | 13824 | 21420 | 43200 |
| 200,0 - 2,000 | 266 | 619 | 1151 | 2486 | 3780 | 7200 | 14580 | 22644 | 45720 |
| 220,0 - 2,200 | 281 | 652 | 1202 | 2617 | 3996 | 7560 | 15336 | 23760 | 47880 |
| 240,0 - 2,400 | 288 | 680 | 1256 | 2740 | 4176 | 7920 | 16056 | 24876 | 50400 |
| 260,0 - 2,600 | 306 | 713 | 1310 | 2855 | 4356 | 8244 | 16740 | 25920 | 52200 |
| 280,0 - 2,800 | 317 | 742 | 1364 | 2970 | 4356 | 8566 | 17338 | 26928 | 54360 |
| 300,0 - 3,000 | 331 | 767 | 1415 | 3076 | 4680 | 8892 | 18000 | 27900 | 56160 |
Pipe capacity table depending on diameter (according to Shevelev)
The tables of F.A. and A.F. Shevelev are one of the most accurate tabular methods for calculating the throughput of a water supply system. In addition, they contain all the necessary calculation formulas for each specific material. This is a voluminous informative material used by hydraulic engineers most often.
The tables take into account:
- pipe diameters - internal and external;
- wall thickness;
- service life of the pipeline;
- line length;
- pipe assignment.
Hydraulic Calculation Formula
For water pipes, the following calculation formula applies:
Online calculator: pipe capacity calculation
If you have any questions, or if you have any guides that use methods not mentioned here, write in the comments.