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
HTML5 doesn't work in your browserWhen 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 outside diameter and pipeline wall thickness
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
In some cases, you have to deal with the need to calculate water flow through a pipe. This indicator tells you how much water the pipe can pass, measured in m³/s.
- For organizations that have not installed a water meter, fees are calculated based on pipe trafficability. It is important to know how accurately these data are calculated, for what and at what rate you need to pay. Individuals this does not apply, for them, in the absence of a meter, the number of registered people is multiplied by the water consumption of 1 person according to sanitary standards. This is quite a large volume, and with modern tariffs it is much more profitable to install a meter. In the same way, in our time it is often more profitable to heat the water yourself with a water heater than to pay utility services for their hot water.
- Calculation of pipe patency plays a huge role when designing a house, when connecting communications to the house .
It is important to make sure that each branch of the water supply can receive its share from the main pipe, even during peak water consumption hours. The water supply system was created for comfort, convenience, and to make work easier for people.
If water practically does not reach the residents of the upper floors every evening, what kind of comfort can we talk about? How can you drink tea, wash dishes, bathe? And everyone drinks tea and swims, so the volume of water that the pipe was able to provide was distributed over the lower floors. This problem can play a very bad role in firefighting. If firefighters connect to the central pipe, but there is no pressure in it.
Sometimes calculating the water flow through a pipe can be useful if, after repairing the water supply system by unfortunate craftsmen, replacing part of the pipes, the pressure has dropped significantly.
Hydrodynamic calculations are not an easy task; they are usually carried out by qualified specialists. But let’s say you are engaged in private construction, designing your own cozy, spacious house.
How to calculate the water flow through a pipe yourself?
It would seem that it is enough to know the diameter of the pipe hole to obtain, perhaps rounded, but generally fair figures. Alas, this is very little. Other factors can change the result of calculations significantly. What affects the maximum flow of water through a pipe?
- Pipe section. An obvious factor. Starting point for fluid dynamics calculations.
- Pipe pressure. As pressure increases, more water flows through a pipe with the same cross-section.
- Bends, turns, changes in diameter, branches slow down the movement of water through the pipe. Different variants to varying degrees.
- Pipe length. Longer pipes will carry less water per unit of time than in short ones. The whole secret is in the force of friction. Just as it delays the movement of objects familiar to us (cars, bicycles, sleds, etc.), the force of friction impedes the flow of water.
- A pipe with a smaller diameter turns out to have more area contact of water with the surface of the pipe in relation to the volume of water flow. And from each point of contact a friction force appears. Just like in longer pipes, in narrower pipes the speed of water movement becomes slower.
- Pipe material. It is obvious that the degree of roughness of the material affects the magnitude of the friction force. Modern plastic materials(polypropylene, PVC, metal, etc.) prove to be very slippery compared to traditional steel and allow water to move faster.
- Pipe service life. Lime deposits and rust greatly impair the throughput of the water supply system. This is the most tricky factor, because the degree of clogging of the pipe, its new internal relief and the coefficient of friction are very difficult to calculate with mathematical accuracy. Fortunately, water flow calculations are most often required for new construction and fresh, previously unused materials. On the other hand, this system will connect to existing communications that have existed for many years. And how will she behave in 10, 20, 50 years? Newest technologies have improved this situation significantly. Plastic pipes do not rust, their surface practically does not deteriorate over time.
Calculation of water flow through a tap
The volume of fluid flowing out is found by multiplying the cross-section of the pipe opening S by the flow rate V. The cross-section is the area of a certain part volumetric figure, in this case, the area of the circle. Found by the formula S = πR2. R will be the radius of the pipe opening, not to be confused with the radius of the pipe. π is a constant, the ratio of the circumference of a circle to its diameter, approximately equal to 3.14.
The flow rate is found using Torricelli's formula: . Where is g acceleration free fall, on planet Earth equal to approximately 9.8 m/s. h is the height of the water column that stands above the hole.
Example
Let us calculate the water flow through a tap with a hole with a diameter of 0.01 m and a column height of 10 m.
Hole cross section = πR2 = 3.14 x 0.012 = 3.14 x 0.0001 = 0.000314 m².
Outflow velocity = √2gh = √2 x 9.8 x 10 = √196 = 14 m/s.
Water flow = SV = 0.000314 x 14 = 0.004396 m³/s.
Converted to liters, it turns out that 4.396 liters per second can flow from a given pipe.
When laying water mains, the most difficult thing to calculate is throughput pipe sections. Correct calculations will ensure that the water consumption is not too high and its pressure does not decrease.
The importance of correct calculations
Calculating water consumption allows you to choose the right pipe material and diameter
When designing a cottage with two or more bathrooms or a small hotel, one must take into account how much water the pipes of the selected section can supply. After all, if the pressure in the pipeline drops due to high consumption, this will lead to the fact that it will be impossible to take a normal shower or bath. If the problem arises in a fire, you could lose your home altogether. Therefore, the calculation of the trafficability of highways is carried out even before the start of construction.
It is also important for small business owners to know throughput rates. Indeed, in the absence of metering devices, utility services, as a rule, present an invoice for water consumption to organizations based on the volume passed through the pipe. Knowing the data on your water supply will allow you to control water consumption and not pay extra.
What determines the permeability of a pipe?
Water consumption will depend on the configuration of the water supply system, as well as the type of pipes from which the network is installed
The permeability of pipe sections is a metric value that characterizes the volume of liquid passed through the pipeline over a certain time interval. This indicator depends on the material used in the production of pipes.
Plastic pipelines maintain almost the same permeability throughout the entire operational period. Plastic, compared to metal, does not rust, so the lines do not become clogged for a long time.
For metal models, throughput decreases year after year. As the pipes rust, the inner surface gradually peels off and becomes rough. Because of this, much more plaque forms on the walls. Hot water pipes in particular clog quickly.
In addition to the material of manufacture, cross-country ability also depends on other characteristics:
- Pipeline lengths. The greater the length, the lower the flow velocity due to the influence of friction, and the pressure decreases accordingly.
- Pipe diameter. The walls of narrow highways create more resistance. The smaller the cross-section, the worse the ratio of flow velocity to internal area will be over a section of a fixed length. Wider pipes move water faster.
- Presence of turns, fittings, adapters, taps. Any shaped parts slow down the movement of water flows.
When determining the throughput indicator, it is necessary to take into account all these factors in combination. In order not to get confused in the numbers, you should use proven formulas and tables.
Calculation methods
The friction coefficient is affected by the presence of locking elements and their number
To determine the permeability of a water supply system, you can use three calculation methods:
The last method, although the most accurate, is not suitable for calculating ordinary household communications. It is quite complex, and to use it you will need to know a variety of indicators. To calculate simple network for a private home, you should use an online calculator. Although it is not as accurate, it is free and does not need to be installed on your computer. You can achieve more accurate information by checking the data calculated by the program with the table.
How to Calculate Bandwidth
The tabular method is the simplest. Several calculation tables have been developed: you can choose the one that is suitable depending on the known parameters.
Calculation based on pipe section
SNiP 2.04.01-85 proposes to find out the amount of water consumption by the girth of the pipe.
In accordance with SNiP standards, daily water consumption by one person is no more than 60 liters. This data is for a home without running water. If a water supply network is installed, the volume increases to 200 liters.
Calculation based on coolant temperature
As the temperature rises, the permeability of the pipe decreases - the water expands and thereby creates additional friction.
You can calculate the necessary data using a special table:
| Pipe section (mm) | Bandwidth | |||
| By heat (hl/h) | By coolant (t/h) | |||
| Water | Steam | Water | Steam | |
| 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 |
For plumbing, this information is not extremely important, but for heating circuits it is considered the main indicator.
Find data based on pressure
The water flow pressure of the common main is taken into account when selecting pipes
When selecting pipes for installation of any communication network it is necessary to take into account the flow pressure in the common line. If pressure is provided high pressure, it is necessary to install pipes with a larger cross-section than when moving by gravity. If these parameters are not taken into account when selecting pipe sections, and a large water flow is passed through small networks, they will begin to make noise, vibrate and quickly become unusable.
To find the largest calculated water consumption, a table of pipe capacity is used depending on the diameter and different water pressure indicators:
| Consumption | Bandwidth | |||||||||
| Pipe section | 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 | 1000,0 | 184 | 425 | 788 | 1724 | 2632 | 5004 | 10152 | 15768 | 31932 |
| 120,0 | 1200,0 | 202 | 472 | 871 | 1897 | 2898 | 5508 | 11196 | 17352 | 35100 |
| 140,0 | 1400,0 | 220 | 511 | 943 | 2059 | 3143 | 5976 | 12132 | 18792 | 38160 |
| 160,0 | 1600,0 | 234 | 547 | 1015 | 2210 | 3373 | 6408 | 12996 | 20160 | 40680 |
| 180,0 | 1800,0 | 252 | 583 | 1080 | 2354 | 3589 | 6804 | 13824 | 21420 | 43200 |
| 200,0 | 2000,0 | 266 | 619 | 1151 | 2488 | 3780 | 7200 | 14580 | 22644 | 45720 |
| 220,0 | 2200,0 | 281 | 652 | 1202 | 2617 | 3996 | 7560 | 15336 | 23760 | 47880 |
| 240,0 | 2400,0 | 288 | 680 | 1256 | 2740 | 4176 | 7920 | 16056 | 24876 | 50400 |
| 260,0 | 2600,0 | 306 | 713 | 1310 | 2855 | 4356 | 8244 | 16740 | 25920 | 52200 |
| 280,0 | 2800,0 | 317 | 742 | 1364 | 2970 | 4356 | 8568 | 17338 | 26928 | 54360 |
| 300,0 | 3000, | 331 | 767 | 1415 | 3078 | 4680 | 8892 | 18000 | 27900 | 56160 |
The average pressure in most risers varies from 1.5 to 2.5 atmospheres. The dependence on the number of floors is regulated by dividing the water supply network into several branches. Injecting water through pumps also affects the change in flow speed.
Also, when calculating the water flow through a pipe using a table of pipe diameter and pressure values, not only the number of taps is taken into account, but also the number of water heaters, bathtubs and other consumers.
Hydraulic calculation according to Shevelev
To most accurately identify the indicators of the entire water supply network, special reference materials are used. They define the running characteristics for pipes made of different materials.
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.
Water consumption parameters:
- The diameter of the pipe, which also determines further throughput.
- 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 using the following data:
- Structural material for pipe construction.
- Technology affecting the pipeline assembly process.
The characteristics affect the pressure inside the water supply system and determine the water flow.
If you are looking for an answer to the question of how to determine water consumption, then you must understand two calculation formulas that determine the parameters of use.
- The formula for calculating per day is Q=ΣQ×N/100. Where ΣQ is the annual daily water use per inhabitant, and N is the number of residents in the building.
- 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 consumption, which will show the needs and requirements of a given home. There are tables that can be used to calculate liquids.
Reference data for water calculations
When using tables, you should calculate all the faucets, 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 with high-quality running water and a bathroom.
- 350 liters - for 1 person with running water, built-in appliances, bath, toilet.
Why calculate water according to SNiP?
How to determine water consumption for every day is not the most popular information among ordinary residents of the house, but pipeline installation specialists 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 to determine these indicators, you need to know how much water is needed in the pipeline.
A formula that helps determine the diameter of the pipe and the speed of fluid flow:
The standard fluid speed in a system without pressure is 0.7 m/s and 1.9 m/s. And the speed is from external source, for example a boiler, is determined by the source passport. Knowing the diameter determines the flow rate in communications.
Calculation of water pressure loss
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 – ductility.
The friction indicator varies from the following values:
- coating roughness level;
- obstacles in the equipment at locking points;
- fluid flow speed;
- pipeline length.
Easy calculation
Knowing pressure loss, fluid velocity in pipes and volume required water, how to determine water flow and pipeline sizes becomes much clearer. But in order to get rid of long calculations, you can use a special table.
Where D is the pipe diameter, q is the consumer water flow, and V is the water speed, i is the course. To determine the values, they must be found in the table and connected in a straight line. The flow rate and diameter are also determined, taking into account the slope and speed. Therefore, the most in a simple way calculation is the use of tables and graphs.