Water consumption in a pipe calculator. Pipe capacity: simple about the complex. Water flow through a pipe: is a simple calculation possible

Water flow parameters:

1. The value of the pipe diameter, which also determines the further throughput.
2. The size of the pipe walls, which will then determine the internal pressure in the system.

The only thing that does not affect consumption is the length of communications.

If the diameter is known, the calculation can be carried out according to the following data:

1. Structural material for pipe construction.
2. Technology affecting the pipeline assembly process.

Characteristics affect the pressure inside the water supply system and determine the flow of water.

If you are looking for an answer to the question of how to determine the flow of water, then you must learn two calculation formulas that determine the parameters of use.

1. The formula for daily calculation is Q=ΣQ×N/100. Where ΣQ is the annual daily water use per 1 inhabitant, and N is the number of inhabitants in the building.
2. The formula for calculating per hour is q=Q×K/24. Where Q is the daily calculation, and K is the ratio according to SNiP, uneven consumption (1.1-1.3).

These simple calculations can help determine the expense, which will show the needs and requirements of this house. There are tables that can be used in calculating the liquid.

Reference data in the calculation of water

When using tables, you should calculate all the taps, bathtubs and water heaters in the house. Table SNiP 2.04.02-84.

Standard consumption rates:

• 60 liters - 1 person.
• 160 liters - for 1 person, if the house has better plumbing.
• 230 liters - for 1 person, in a house where high-quality plumbing and a bathroom are installed.
• 350 liters - for 1 person with running water, built-in appliances, bathroom, toilet.

Why calculate water according to SNiP?

How to determine the water flow for each day is not the most requested information among ordinary residents of the house, but pipeline installers need this information even less. And for the most part, they need to know what the diameter of the connection is, and what pressure it maintains in the system.

But in order to determine these indicators, you need to know how much water is needed in the pipeline.

The formula to help determine the pipe diameter and fluid flow rate:

The standard liquid velocity in a headless system is 0.7 m/s and 1.9 m/s. And the speed from an external source, such as a boiler, is determined by the source passport. When the diameter is known, the flow rate in communications is determined.

Water head loss calculation

The loss of water flow is calculated taking into account the pressure drop using one formula:

In the formula, L - denotes the length of the connection, and λ - friction loss, ρ - malleability.

The friction index varies from the following values:

• the level of roughness of the coating;
• obstacle in the equipment at the locking points;
• fluid flow rate;
• pipeline length.

Ease of calculation

Knowing pressure loss, fluid velocity in pipes and volume required water how to determine the flow of water and the size of the pipeline becomes much clearer. But in order to get rid of long calculations, you can use a special table.

Where D is the diameter of the pipe, q is the consumption of water, and V is the speed of the water, i is the course. To determine the values, they must be found in the table and connected in a straight line. Also determine the flow rate and diameter, while taking into account the slope and speed. Therefore, the most in a simple way calculation is the use of tables and graphs.

In order to properly mount the water supply structure, starting the development and planning of the system, it is necessary to calculate the flow of water through the pipe.

The main parameters of the home conduit depend on the data obtained.

In this article, readers will be able to get acquainted with the basic techniques that will help them independently calculate their plumbing system.

The purpose of calculating the diameter of the pipeline by flow: Determination of the diameter and cross section of the pipeline based on data on the flow rate and the rate of longitudinal movement of water.

It is rather difficult to perform such a calculation. It is necessary to take into account a lot of nuances related to technical and economic data. These parameters are interconnected. The diameter of the pipeline depends on the type of liquid that will be pumped through it.

If you increase the flow rate, you can reduce the diameter of the pipe. Material consumption will automatically decrease. It will be much easier to mount such a system, the cost of work will fall.

However, an increase in flow movement will cause head losses, which require the creation of additional energy for pumping. If you reduce it too much, undesirable consequences may appear.

When designing a pipeline, in most cases, the amount of water flow is immediately set. Two quantities remain unknown:

• Pipe diameter;
• Flow rate.

It is very difficult to make a complete technical and economic calculation. This requires appropriate engineering knowledge and a lot of time. To facilitate this task, when calculating desired diameter pipes, enjoy reference materials. They give the values ​​of the best flow rate obtained empirically.

The final calculation formula for optimal diameter pipeline looks like this:

d = √(4Q/Πw)
Q is the flow rate of the pumped liquid, m3/s
d – pipeline diameter, m
w is the flow velocity, m/s

Suitable liquid velocity, depending on the type of pipeline

First of all, take into account minimum costs, without which it is impossible to pump liquid. In addition, the cost of the pipeline must be considered.

When calculating, you must always remember about the speed limits of the moving medium. In some cases, the size of the main pipeline must meet the requirements laid down in the technological process.

The dimensions of the pipeline are also affected by possible pressure surges.

When are done preliminary calculations, the change in pressure is not taken into account. Permissible speed is taken as the basis for designing a process pipeline.

When there are changes in the direction of movement in the pipeline being designed, the surface of the pipe begins to experience a large pressure directed perpendicular to the flow movement.

This increase is due to several indicators:

• Fluid speed;
• Density;
• Initial pressure (pressure).

Moreover, the speed is always in inverse proportion to the diameter of the pipe. That is why high-velocity fluids require right choice configurations, competent selection of pipeline dimensions.

For example, if sulfuric acid is being pumped, the velocity value is limited to a value that will not cause erosion on the walls of the pipe bends. As a result, the structure of the pipe will never be broken.

Water velocity in pipeline formula

The volume flow V (60m³/h or 60/3600m³/s) is calculated as the product of the flow velocity w times transverse section pipe S (and the cross section, in turn, is considered as S = 3.14 d² / 4): V = 3.14 w d² / 4. From here we get w = 4V/(3.14 d²). Don't forget to convert the diameter from millimeters to meters, i.e. the diameter will be 0.159 m.

Water consumption formula

AT general case The methodology for measuring water flow in rivers and pipelines is based on a simplified form of the continuity equation, for incompressible fluids:

Water flow through pipe table

Flow vs pressure

There is no such dependence of fluid flow on pressure, but there is - on pressure drop. The formula is simple. There is a generally accepted equation for the pressure drop during the flow of liquid in a pipe Δp = (λL/d) ρw²/2, λ is the coefficient of friction (it is searched depending on the speed and diameter of the pipe according to the graphs or the corresponding formulas), L is the length of the pipe, d is its diameter , ρ - fluid density, w - speed. On the other hand, there is a definition of flow G = ρwπd²/4. We express the speed from this formula, substitute it into the first equation and find the dependence of the flow rate G = π SQRT(Δp d^5/λ/L)/4, SQRT is the square root.

The coefficient of friction is sought by selection. First, you set some value of the fluid velocity from the flashlight and determine the Reynolds number Re=ρwd/μ, where μ is the dynamic viscosity of the fluid (do not confuse it with the kinematic viscosity, these are different things). According to Reynolds, you are looking for the coefficient of friction λ = 64 / Re for laminar mode and λ = 1 / (1.82 lgRe - 1.64)² for turbulent (here lg is the decimal logarithm). And take the value that is higher. After you find the flow rate and speed, you will need to repeat the entire calculation again with a new coefficient of friction. And you repeat this recalculation until the speed value specified for determining the friction coefficient coincides to some error with the value that you find from the calculation.

Water consumption in a watercourse is the volume of liquid passing through a cross section. Consumable unit - m3/s.

The calculation of the consumed water should be carried out at the planning stage of the water pipeline, since the main parameters of the water pipelines depend on this.

Water consumption in the pipeline: factors

In order to independently perform the calculation of the water flow in the pipeline, it is necessary to know the factors that ensure the permeability of water in the pipeline.

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

1. Pipe length. Everything is clear with this: the longer its length, the higher the degree of friction of water against its walls, so the fluid flow slows down.
2. The material of the pipe walls is also an important factor on which the flow rate depends. So, the smooth walls of a pipe made of polypropylene give the least resistance than steel.
3. The diameter of the pipeline - the smaller it is, the higher the resistance of the walls to the movement of fluid. The narrower the diameter, the more disadvantageous is the correspondence of the outer surface area to the inner volume.
4. Service life of the pipeline. We know that over the years they are exposed to corrosion, and lime deposits form on cast iron. 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 a new one made of steel. /li>
5. Changing the diameter to different areas conduits, turns, shut-off fittings or fittings significantly reduce the speed of the water flow.

What quantities are used to calculate the flow of water?

The following quantities are used in the formulas:

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

Formula for calculating water consumption

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

1. For daily calculation - Q=Q×N/100
2. For hourly calculation - q=Q×K/24.
3. Diameter calculation - q= ×d2/4 ×V.

Example of calculating water consumption for a residential consumer

The house has a toilet, washbasin, bathtub, kitchen sink.

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

It can be converted to m3/hour by multiplying it by 3.6. Thus it turns out: 0.4 x 3.6 \u003d 1.44 cubic meters / hour

The 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 version.

If you are planning to start building a house, redeveloping an apartment or installing plumbing structures, then information on how to calculate the water consumption will be most welcome. Calculating the water consumption will not only help determine the required volume of water for a particular room, but will also allow you to timely identify pressure drops in the pipeline. In addition, thanks to simple formulas, all this can be done independently, without resorting to the help of specialists.

At enterprises, as well as in apartments and houses in general, it is spent a large number of water. The numbers are huge, but can they say anything else, except for the fact of a certain expense? Yes they can. Namely, the water flow can help calculate the diameter of the pipe. It would seem that these parameters are not related to each other, but in fact the relationship is obvious.

After all, the throughput of the water supply system depends on many factors. A significant place in this list is precisely the diameter of the pipes, as well as the pressure in the system. Let's delve deeper into this issue.

Factors affecting the permeability of water through a pipe

Water flow through a pipe round section, which has a hole, depends on the size of this hole. Thus, the larger it is, the more water will pass through the pipe in a certain period of time. However, do not forget about pressure. After all, you can give an example. A meter pillar will push water through a centimeter hole much less per unit time than a pillar with a height of several tens of meters. It is obvious. Therefore, the water flow will reach its maximum at the maximum internal section of the product, as well as at the maximum pressure.

Diameter calculation

If you need to get a certain water flow at the outlet of the water supply system, then you can not do without calculating the diameter of the pipe. After all, this indicator, along with the rest, affects the throughput rate.

Of course, there are special tables that are on the Web and in specialized literature that allow you to bypass the calculations, focusing on certain parameters. However high precision you should not expect from such data, the error will still be present, even if all factors are taken into account. So best way out for accurate results - self-calculation.

For this you will need the following data:

• Water consumption consumption.
• Head loss from the starting point to the point of consumption.

It is not necessary to calculate the consumption of water consumption - there is a digital standard. You can take data on the mixer, which says that about 0.25 liters are consumed per second. This figure can be used for calculations.

An important parameter for obtaining accurate data is the head loss in the area. As you know, the head pressure in standard water supply risers is in the range from 1 to 0.6 atmospheres. Average- 1.5-3 atm. The parameter depends on the number of floors in the house. But this does not mean that the higher the house, the higher the pressure in the system. In very tall buildings (more than 16 floors), a division of the system into floors is sometimes used to normalize the pressure.

With regard to head loss, this figure can be calculated using pressure gauges at the starting point and before the point of consumption.

If, nevertheless, knowledge and patience for self-calculation is not enough, then you can use tabular data. And let them have certain errors, the data will be accurate enough to certain conditions. And then, according to the water consumption, it will be very easy and quick to get the diameter of the pipe. This means that the water supply system will be calculated correctly, which will make it possible to obtain such an amount of liquid that will satisfy the needs.

Method for calculating the Shevelev table theoretical hydraulics SNiP 2.04.02-84

Initial data

Pipe material: New steel without internal protective coating or with bituminous protective coating New cast iron without an internal protective coating or with a bituminous protective coating Non-new steel and cast iron without an internal protective coating or with a bitumen protective coating plastic or polymer-cement coating, applied by spin coating Steel and cast iron, with internal cement-sand coating spray-applied Steel and cast-iron, with an internal sand-cement coating, applied by centrifugation polymer materials(plastic) Glass

Estimated consumption

l/s m3/h

Outside diameter mm

Wall thickness mm

Pipeline length m

Average water temperature °C

Eq. roughness inside. pipe surfaces: Heavily rusted or heavily deposited Steel or cast iron old rusted Steel galv. 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

Sum of sets of local resistances

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 such a problem, you need to make a hydraulic calculation of your system, and for even more simple solution- you can use online hydraulic calculation which we will now do.
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 piping material
3. Set the estimated water flow in the pipeline
4. Set outside diameter and pipeline wall thickness
5. Set the piping length
6. Set the average water temperature
The result of the calculation will be the graph and the following hydraulic calculation values.
The graph consists of two values ​​(1 - water head loss, 2 - water speed). The optimum pipe diameter values ​​will be written in green below the graph.

Those. you must set the diameter so that the point on the graph is exactly above your green values ​​for the pipeline diameter, because only at such values ​​will the water velocity and head loss be optimal.

The pressure loss in the pipeline 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 velocity of liquid/air/gas in a pipeline of various sections, use