Calculation of water based on pipe capacity. How to calculate water flow through a pipe based on pressure and diameter. Calculation of pipe diameter for water supply and heating

This characteristic depends on several factors. First of all, this is the diameter of the pipe, as well as the type of liquid, and other indicators.

For hydraulic calculation of a pipeline, you can use the hydraulic pipeline calculation calculator.

When calculating any systems based on fluid circulation through pipes, there is a need to accurately determine bandwidth pipes. This is a metric value that characterizes the amount of liquid flowing through pipes over a certain period of time. This indicator is directly related to the material from which the pipes are made.

If we take, for example, plastic pipes, they differ in almost the same throughput throughout their entire service life. Plastic, unlike metal, is not prone to corrosion, so a gradual increase in deposits is not observed in it.

As for metal pipes, they throughput decreases year after year. Due to the appearance of rust, the material inside the pipes peels off. This leads to surface roughness and the formation of even more plaque. This process occurs especially quickly in hot water pipes.

The following is a table of approximate values, which was created to make it easier to determine the throughput of pipes in apartment wiring. This table does not take into account the reduction in throughput due to the appearance of sedimentary build-ups inside the pipe.

Table of pipe capacity for liquids, gas, water vapor.

Type of liquid	Speed (m/sec)
City water
Water pipeline
Water system central heating
Pressure system water in pipeline line
Hydraulic fluid	up to 12m/sec
Oil pipeline line
Oil in the pressure system of the pipeline line
Steam in the heating system
Steam central piping system
Steam in a heating system with high temperature
Air and gas in central system pipeline

Most often, it is used as a coolant plain water. The rate of decrease in throughput in pipes depends on its quality. The higher the quality of the coolant, the longer the pipeline made of any material (steel, cast iron, copper or plastic) will last.

Calculation of pipe capacity.

For accurate and professional calculations, you must use the following indicators:

The material from which pipes and other elements of the system are made;
Pipe length
Number of water consumption points (for water supply system)

An example of calculating pipeline capacity.

Pipeline length is an important indicator when calculating throughput. The length of the pipeline has a significant impact on throughput indicators. The greater the distance water travels, the less pressure it creates in the pipes, which means the flow speed decreases.

Here are some examples. Based on tables developed by engineers for these purposes.

Pipe capacity:

0.182 t/h with a diameter of 15 mm
0.65 t/h with pipe diameter 25 mm
4 t/h with a diameter of 50 mm

As can be seen from the examples given, larger diameter increases flow rate. If the diameter is doubled, the throughput will also increase. This dependence must be taken into account when installing any liquid system, be it plumbing, drainage or heat supply. Especially it concerns heating systems, since in most cases they are closed, and the heat supply in the building depends on the uniform circulation of the liquid.

Water consumption in a stream is the volume of liquid passing through cross section. The consumption unit is m3/s.

Calculation of water consumption should be carried out at the planning stage of the water supply system, since the main parameters of the water pipelines depend on this.

Water flow in the pipeline: factors

In order to independently calculate the water flow in the pipeline, you need to know the factors that ensure the passage of water in the pipeline.

The main ones are the degree of pressure in the water pipeline and the cross-sectional diameter of the pipe. But, knowing only these values, it will not be possible to accurately calculate water consumption, since it also depends on such indicators as:

Pipe length. This is all clear: the longer its length, the higher the degree of friction of water against its walls, so the flow of liquid slows down.
The material of the pipe walls is also an important factor on which the flow rate depends. Thus, the smooth walls of a polypropylene pipe provide the least resistance than steel.
The diameter of the pipeline - the smaller it is, the higher the resistance of the walls to fluid movement will be. The narrower the diameter, the more unfavorable it is to match the outer surface area to the inner volume.
Service life of the water supply system. We know that over the years they are exposed to corrosion, and cast iron deposits form on them. The friction force against the walls of such a pipe will be significantly higher. For example, the surface resistance of a rusty pipe is 200 times higher than that of a new steel pipe.
Changing the diameter by different areas culverts, bends, shut-off fittings or fixtures significantly reduce the speed of water flow.

What quantities are used to calculate water flow?

The following quantities are used in the formulas:

Q – total (annual) water consumption per person.
N is the number of residents of the house.
Q – daily flow rate.
K is the consumption unevenness coefficient equal to 1.1-1.3 (SNiP 2.04.02-84).
D – pipe diameter.
V – water flow speed.

Formula for calculating water consumption

So, knowing the values, we get the following formula for water consumption:

For daily calculation – Q=Q×N/100
For hourly calculation – q=Q×K/24.
Calculation by diameter - q= ×d2/4 ×V.

An example of calculating water consumption for a household consumer

The house is equipped with: toilet, washbasin, bathtub, kitchen sink.

According to Appendix A, we take the flow rate per second:
- Toilet - 0.1 l/sec.
- Washbasin with mixer - 0.12 l/sec.
- Bath - 0.25 l/sec.
- Kitchen sink - 0.12 l/sec.
The amount of water consumed from all supply points will be:
- 0.1+0.12+0.25+0.12 = 0.59 l/sec
According to the total flow rate (Appendix B), 0.59 l/sec corresponds to the calculated flow rate of 0.4 l/sec.

You can convert it to m3/hour by multiplying it by 3.6. Thus it turns out: 0.4 x 3.6 = 1.44 cubic meters / hour

Procedure for calculating water consumption

The entire calculation procedure is specified in the set of rules 30. 13330. 2012 SNiP 2.04.01-85 * “Internal water supply and sewerage”, updated edition.

If you are planning to start building a house, remodeling an apartment or installing plumbing structures, then information on how to calculate water consumption will be very helpful. Calculating water consumption will help not only determine the required volume of water for a particular room, but will also allow timely detection of a decrease in pressure in the pipeline. In addition, thanks to simple formulas, you can do all this yourself, without the help of specialists.

Laying a pipeline is not very difficult, but quite troublesome. One of the most complex problems this involves calculating the pipe capacity, which directly affects the efficiency and performance of the structure. This article will discuss how pipe capacity is calculated.

Throughput is one of the most important indicators of any pipe. Despite this, this indicator is rarely indicated in pipe markings, and there is little point in this, because the throughput capacity 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 pipeline capacity

External diameter. This indicator is expressed in the distance from one side of the outer wall to the other side. In calculations, this parameter is designated Day. The outer diameter of the pipes is always indicated in the markings.
Diameter conditional passage . This value is defined as the diameter of the internal section, which is rounded to whole numbers. When calculating, the nominal diameter is displayed as Dn.

Calculation of pipe permeability can be carried out using one of the methods, which must be selected depending on the specific conditions of pipeline laying:

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 there is its own set of formulas, as for other types of structures.
Spreadsheet calculations . You can select the optimal cross-country ability using a table with approximate values, which is most often used for arranging wiring in an apartment. The values indicated in the table are quite vague, but this does not prevent them from being used in calculations. The only drawback of the tabular method is that it calculates the throughput of the pipe depending on the diameter, but does not take into account changes in the latter due to deposits, therefore, for highways susceptible to build-up, such a calculation will not be possible. best choice. To obtain accurate results, you can use Shevelev’s table, which takes into account almost all factors affecting pipes. This table is perfect for installing highways on individual plots of land.
Calculation using programs. Many companies specializing in pipeline laying use computer programs in their activities that allow them to accurately calculate not only the pipe capacity, but also a host of other indicators. For independent calculations You can use online calculators, which, although they have a slightly larger error, are available free of charge. A 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 pipeline installation depending on the region.

Calculation of gas pipeline capacity

Gas pipeline design requires sufficient high precision– gas has a very high compression ratio, due to which leaks are possible even through microcracks, not to mention serious ruptures. That is why correct calculation of the capacity of the pipe through which gas will be transported is very important.

If we're talking about on gas transportation, then the throughput of pipelines depending on the diameter will be calculated using 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;

DN – the value of the nominal diameter of the pipe.

The above formula for calculating the capacity of a pipe by diameter allows you to create a system that will work in domestic conditions.

In industrial construction and when performing professional calculations, a different formula is used:

Qmax = 196.386 DN2 * p/z*T,

Where z is the compression ratio of the transported medium;

T – temperature of the transported gas (K).

To avoid problems, professionals also have to take into account when calculating the pipeline climatic conditions in the region where it will take place. If outside diameter pipes will be less than the gas pressure in the system, then the pipeline is very likely to be damaged during operation, resulting in a loss of the transported substance and an increased risk of explosion on the weakened section of the pipe.

If necessary, you can determine the patency gas pipe using a table that describes the relationship between the most common pipe diameters and the operating pressure level in them. By and large, the tables have the same drawback that the pipeline capacity calculated by diameter has, namely, the inability to take into account the influence of external factors.

Calculation of sewer pipe capacity

When designing a sewer system, it is imperative to calculate the throughput of the pipeline, which directly depends on its type (sewage systems are either pressure or non-pressure). Hydraulic laws are used to carry out calculations. The calculations themselves can be carried out either using formulas or using appropriate tables.

For the hydraulic calculation of the sewer system, the following indicators are required:

Pipe diameter – DN;
The average speed of movement of substances is v;
The magnitude of the hydraulic slope is I;
Filling degree – h/DN.

As a rule, when carrying out calculations, only the last two parameters are calculated - the rest can then be determined without any problems. The magnitude of the hydraulic slope is usually equal to the slope of the ground, which will ensure the movement of wastewater at the speed necessary for self-cleaning of the system.

The speed and maximum level of filling of domestic sewerage are determined from a table that can be written out as follows:

150-250 mm - h/DN is 0.6 and speed is 0.7 m/s.
Diameter 300-400 mm - h/DN is 0.7, speed is 0.8 m/s.
Diameter 450-500 mm - h/DN is 0.75, speed is 0.9 m/s.
Diameter 600-800 mm - h/DN is 0.75, speed is 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 standard indicators for the minimum pipeline slope:

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.

To calculate the volume of wastewater, the following formula is used:

q = a*v,

Where a is the open cross-sectional area of the flow;

v – speed of wastewater transportation.

The speed 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 – wetting coefficient;

i is the degree of slope of the structure.

From the previous formula we can derive the following, which will allow us 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 material of the pipe).

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 in direct contact with the liquid.

Tabular calculation of sewer pipes

You can also determine the permeability of sewer system pipes using tables, and the calculations will directly depend on the type of system:

Gravity sewerage. To calculate free-flow sewer systems, tables are used that contain all the necessary indicators. Knowing the diameter of the pipes being 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 patency of the pipeline. 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. Determining the throughput in this type of system using tables is somewhat simpler - it is enough to know the maximum degree of filling of the pipeline and the average speed of liquid transportation. Read also: "".

Bandwidth table polypropylene pipes allows you to find out all the parameters necessary for arranging the system.

Calculation of water supply capacity

Water pipes are most often used in private construction. In any case, the water supply system is subject to a serious load, so calculating the pipeline capacity is mandatory, because it allows you to create the most comfortable operating conditions for the future structure.

To determine patency water pipes you can use their diameter (read also: " "). Of course, this indicator is not the basis for calculating cross-country ability, but its influence cannot be excluded. The increase in the internal diameter of the pipe is directly proportional to its permeability - that is, a thick pipe almost does not interfere with 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 friction of the fluid on the inside of the pipe (for different materials there are 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 water temperature. As the temperature in the system increases, the fluid expands, causing friction to increase. To determine the permeability of the pipeline, you need to use the appropriate table. There is also a table that allows you to determine the permeability in the pipes depending on the water pressure.

The most accurate calculation of water based on pipe capacity can be made using the Shevelev tables. In addition to accuracy and large numbers standard values, these tables contain formulas that allow you to calculate any system. This material fully describes all situations related to hydraulic calculations, which is why 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;
System operation period;
Total length highways;
Functional purpose systems.

Conclusion

Pipe capacity calculations can be performed different ways. Choice the best way calculation depends on large quantity factors - from pipe sizes to purpose and type of system. In each case, there are more and less accurate calculation options, so both a professional who specializes in laying pipelines and an owner who decides to lay a pipeline at home can find the right one.

Shevelev table calculation method theoretical hydraulics SNiP 2.04.02-84

Initial data

Pipe material: New steel without internal protective coating or with bitumen protective coating New cast iron without an internal protective coating or with a bitumen protective coating New steel and cast iron without an internal protective coating or with a bitumen protective coating Asbestos-cement Reinforced concrete vibrohydropressed Reinforced concrete centrifuged Steel and cast iron with internal. plastic or polymer-cement coating applied by centrifugation Steel and cast iron, with an internal cement-sand coating applied by spraying Steel and cast iron, with an internal cement-sand coating applied by centrifugation From polymer materials(plastic) Glass

Estimated flow

L/s m3/hour

Outside diameter mm

Wall thickness mm

Pipe length m

Average water temperature °C

Eq. internal roughness pipe surfaces: Heavily rusted or with large deposits Steel or cast iron old rusty Galvanized steel. after several years Steel after several years Cast iron new Galvanized steel new Welded steel new Seamless steel new Drawn from brass, lead, copper Glass

Quantity amount local resistance

Calculation

Dependence of pressure loss on pipe diameter

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When calculating a water supply or heating system, you are faced with the task of selecting the diameter of the pipeline. To solve this problem, you need to make a hydraulic calculation of your system, and for even more simple solution– you can use online hydraulic calculation, which is what we will do now.
Operating procedure:
1. Select the appropriate calculation method (calculation according to Shevelev tables, theoretical hydraulics or according to SNiP 2.04.02-84)
2. Select pipe material
3. Set the estimated water flow in the pipeline
4. Set the outer diameter and wall thickness of the pipeline
5. Set the pipe length
6. Set average temperature water
The result of the calculation will be the graph and the hydraulic calculation values given below.
The graph consists of two values (1 – water pressure loss, 2 – water speed). Optimal values pipe diameters will be written in green below the graph.

Those. you must set the diameter so that the point on the graph is strictly above your green values for the pipeline diameter, because only with such values will the water speed and pressure loss be optimal.

Pipeline pressure loss shows the pressure loss in a given section of the pipeline. The higher the losses, the more work will have to be done to deliver water to the right place.
The hydraulic resistance characteristic shows how effectively the pipe diameter is selected depending on the pressure loss.
For reference:
- if you need to find out the speed of liquid/air/gas in a pipeline of various sections, use

A water supply system is a set of pipelines and devices that ensure an uninterrupted supply of water to various sanitary fixtures and other devices that require it to operate. In its turn water supply calculation- this is a set of measures, as a result of which the maximum second, hourly and daily water consumption is initially determined. Moreover, not only the total liquid consumption is calculated, but also the cold and hot water separately. The remaining parameters described in SNiP 2.04.01-85 * "Internal water supply and sewerage of buildings", as well as the diameter of the pipeline, are already dependent on water consumption indicators. For example, one of these parameters is the nominal diameter of the meter.

This article presents example of calculating water supply for internal water supply for private 2 storey building. As a result of this calculation The total second water consumption and pipeline diameters for plumbing fixtures located in the bathroom, toilet and kitchen were found. It also defines the minimum cross-section for the entrance pipe to the house. That is, we mean a pipe that originates at the source of water supply and ends at the point where it branches to consumers.

Regarding the other parameters given in the mentioned regulatory document, then practice shows that it is not necessary to calculate them for a private house.

Example of water supply calculation

Initial data

The number of people living in the house is 4 people.

The house has the following sanitary fixtures.

Bathroom:

Bathroom with faucet - 1 pc.

San. node:

Toilet with flush tank - 1 pc.

Kitchen:

Washbasin with mixer - 1 pc.

Calculation

Formula for maximum second water flow:

q с = 5 q 0 tot α, l/s,

Where: q 0 tot - total liquid consumption of one consumed device, determined in accordance with clause 3.2. We accept by adj. 2 for the bathroom - 0.25 l/s, wc. node - 0.1 l/s, kitchen - 0.12 l/s.

α - coefficient determined according to app. 4 depending on the probability P and the number of plumbing fixtures N.

Determining the probability of operation of sanitary fixtures:

P = (U q hr,u tot) / (q 0 tot ·N·3600) = (4·10.5) / (0.25·3·3600) = 0.0155,

Where: U = 4 people - number of water consumers.

q hr,u tot = 10.5 l - general norm water consumption in liters, by the consumer at the hour of greatest water consumption. We accept according to the adj. 3 for an apartment-type residential building with water supply, sewerage and bathtubs with gas water heaters.

N = 3 pcs. - number of plumbing fixtures.

Determining water flow for a bathroom:

α = 0.2035 - we accept according to the table. 2 adj. 4 depending on NP = 1·0.0155 = 0.0155.

q s = 5·0.25·0.2035 = 0.254 l/s.

Determination of water consumption for toilets. node:

α = 0.2035 - exactly the same as in the previous case, since the number of devices is the same.

q s = 5·0.1·0.2035 = 0.102 l/s.

Determining water consumption for the kitchen:

α = 0.2035 - as in the previous case.

q s = 5·0.12·0.2035 = 0.122 l/s.

Definition total flow water on a private house:

α = 0.267 - since NP = 3·0.0155 = 0.0465.

q s = 5·0.25·0.267 = 0.334 l/s.

Formula for determining the diameter of the water supply pipe in the design area:

d = √((4 q с)/(π·V)) m,

Where: d is the internal diameter of the pipeline in the calculated section, m.

V - water flow speed, m/s. We take it equal to 2.5 m/s according to clause 7.6, which states that the speed of the liquid in the internal water supply cannot exceed 3 m/s.

q c is the fluid flow rate in the area, m 3 /s.

Determining the internal cross-section of a bathroom pipe:

d = √((4 0, 000254)/(3.14·2.5)) = 0.0114 m = 11.4 mm.

Determination of the internal section of the pipe for the bathroom. node:

d = √((4 0, 000102)/(3.14·2.5)) = 0.0072 m = 7.2 mm.

Determining the internal cross-section of a kitchen pipe:

d = √((4 0, 000122)/(3.14·2.5)) = 0.0079 m = 7.9 mm.

Determining the internal cross-section of the entrance pipe to the house:

d = √((4 0, 000334)/(3.14·2.5)) = 0.0131 m = 13.1 mm.

Conclusion: To supply water to a bathtub with a mixer, a pipe with an internal diameter of at least 11.4 mm is required, the toilet bowl to the bathroom. node - 7.2 mm, washbasin in the kitchen - 7.9 mm. As for the inlet diameter of the water supply system into the house (to supply 3 appliances), it must be at least 13.1 mm.