In some cases, one has to face the need to calculate the flow of water through a pipe. This indicator indicates how much water the pipe can pass, measured in m³ / s.

• For organizations that have not put the meter on the water, the charge is based on the patency of the pipe. It is important to know how accurately these data are calculated, for what and at what rate you have 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 by sanitary standards. This is a fairly 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 column than to pay utilities for their hot water.
• Calculation of pipe permeability plays a huge role when designing a house, when bringing 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. Plumbing was created for comfort, convenience, and ease of work for a person.

If every evening water will practically not reach the inhabitants of the upper floors, what kind of comfort can we talk about? How can you drink tea, wash dishes, swim? And everyone drinks tea and bathes, so the volume of water that the pipe could provide was distributed over the lower floors. At all bad role this problem can play in firefighting. If firefighters connect to the central pipe, and there is no pressure in it.

Sometimes calculating the flow of water through a pipe can come in handy if, after repairing the water supply by unfortunate masters, replacing part of the pipes, the pressure has dropped significantly.

Hydrodynamic calculations are not an easy task, usually carried out by qualified specialists. But, let's say you are engaged in private construction, designing your cozy spacious house.

How to calculate the flow of water through the pipe yourself?

It would seem that it is enough to know the diameter of the pipe hole in order to get, maybe, rounded, but generally fair figures. Alas, this is very little. Other factors can change the result of calculations at times. What affects the maximum flow of water through the pipe?

1. Pipe section. obvious factor. Starting point of hydrodynamic calculations.
2. Pipe pressure. As the pressure increases, more water passes through a pipe with the same cross section.
3. Bends, turns, change in diameter, branching block the flow of water through the pipe. Different variants to varying degrees.
4. Pipe length. Longer pipes will carry less water per unit of time than for 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.
5. A pipe with a smaller diameter has more area of ​​water contact with the pipe surface in relation to the volume of water flow. And from each point of contact there is a force of friction. Just like in longer pipes, in narrower pipes the speed of water movement becomes less.
6. Pipe material. Obviously, the degree of roughness of the material affects the magnitude of the friction force. Modern plastic materials(polypropylene, PVC, metal-plastic, etc.) are very slippery compared to traditional steel and allow water to move faster.
7. Duration of pipe operation. Lime deposits, rust greatly impair the throughput of the water supply. This is the most tricky factor, because the degree of clogging of the pipe, its new internal relief and friction coefficient are very difficult to calculate with mathematical accuracy. Fortunately, water flow calculations are most often required for new construction and fresh, unused materials. And on the other hand, this system will be connected to already existing, existing communications for many years. And how will she behave herself in 10, 20, 50 years? Newest technologies greatly improved this situation. 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 outflow velocity V. The cross section is the area of ​​a certain part of the volumetric figure, in this case, the area of ​​a circle. It is found according to 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 value, the ratio of a circle's circumference to its diameter, approximately 3.14.

The flow rate is found by the Torricelli formula: . Where g is the free fall acceleration, on the planet Earth equal to approximately 9.8 m/s. h is the height of the water column 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 \u003d πR2 \u003d 3.14 x 0.012 \u003d 3.14 x 0.0001 \u003d 0.000314 m².

Outflow velocity = √2gh = √2 x 9.8 x 10 = √196 = 14 m/s.

Water consumption \u003d SV \u003d 0.000314 x 14 \u003d 0.004396 m³ / s.

In terms of liters, it turns out that 4.396 liters per second can flow out of a given pipe.

When laying water mains, it is most difficult to calculate the throughput of pipe sections. Correct calculations will ensure that the water flow is not too large and its pressure does not decrease.

The importance of correct calculations

Calculation of water consumption allows you to choose the right material and pipe diameter

When designing a cottage with two or more bathrooms or a small hotel, one must take into account how much water can be supplied by pipes of a selected section. After all, if the pressure in the pipeline drops with high consumption, this will lead to the fact that it will be impossible to take a shower or bath normally. If the problem arises during a fire, you can completely lose your home. Therefore, the calculation of the patency 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, utilities, as a rule, present an invoice for water consumption to organizations according to the volume passed by the pipe. Knowing the data on your water supply will allow you to control the flow of water and not pay too much.

What determines the permeability of the pipe

Water consumption will depend on the configuration of the water supply, as well as the type of pipes from which the network is mounted

The permeability of pipe segments is a metric value that characterizes the volume of fluid passed through the pipeline for a certain time interval. This indicator depends on the material used in the production of pipes.

Pipelines made of plastic retain almost the same patency throughout the entire operational period. Plastic, in comparison with metal, does not rust, thanks to which the lines do not become clogged for a long time.

For metal models, throughput decreases year after year. Due to the fact that the pipes rust, inner surface gradually peels off and becomes rough. Because of this, much more plaque is formed on the walls. In particular, hot water pipes clog quickly.

In addition to the material of manufacture, the permeability also depends on other characteristics:

• Plumbing lengths. The greater the length, the lower the flow velocity due to the effect of friction, and the head decreases accordingly.
• Pipe diameter. The walls of narrow highways create more resistance. The smaller the cross section, the worse the ratio of the flow velocity to the value of the internal area in a section of a fixed length will be. In wider pipelines, water moves faster.
• The presence of turns, fittings, adapters, taps. Any shaped details slow down the movement of water flows.

When determining the throughput rate, it is necessary to take into account all these factors in combination. In order not to get confused in the numbers, it is worth using proven formulas and tables.

Calculation methods

The coefficient of friction is affected by the presence of locking elements and their number

To determine the permeability of the 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 for its application you will need to know a variety of indicators. To calculate a simple network for a private house, you should resort to the help of an online calculator. Although it is not as accurate, it is free and does not need to be installed on a computer. You can achieve more accurate information by comparing the data calculated by the program with the table.

How to Calculate Bandwidth

The tabular method is the easiest. Several counting tables have been developed: you can choose the one that is suitable depending on the known parameters.

Calculation based on pipe section

In SNiP 2.04.01-85, it is proposed to find out the amount of water consumption by the girth of the pipe.

In accordance with the norms of SNiP, daily water consumption by one person is not more than 60 liters. This data is for a house without plumbing. If a water supply network is installed, the volume increases to 200 liters.

Calculation according to the temperature of the coolant

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 (gcl/h)		By heat carrier (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 summing up plumbing system this information is not extremely important, but for heating circuits it is considered the main indicator.

Finding Data Depending on Pressure

The pressure of the water flow of the common line is taken into account when selecting pipes

When selecting pipes for installing any communication network, it is necessary to take into account the flow pressure in the common line. If pressure is provided under 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 make noise, vibrate and quickly become unusable.

To find the highest design water flow, a pipe capacity table is used depending on the diameter and different indicators of water pressure:

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 of the 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. The injection of water through pumps also affects the change in flow rate.

Also, when calculating the flow of water through a pipe according to the 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

For the most accurate identification of indicators of the entire water supply network, special reference materials are used. They define running characteristics for pipes made of different materials.

Sometimes it is very important to accurately calculate the volume of water passing through the pipe. For example, when you need to design new system heating. Hence the question arises: how to calculate the volume of the pipe? This indicator helps to choose the right equipment, for example, the size of the expansion tank. In addition, this indicator is very important when antifreeze is used. It is usually sold in several forms:

• Diluted;
• Undiluted.

The first type can withstand temperatures - 65 degrees. The second will freeze already at -30 degrees. To buy right amount antifreeze, you need to know the volume of coolant. In other words, if the volume of liquid is 70 liters, then 35 liters of undiluted liquid can be purchased. It is enough to dilute them, observing the proportion of 50–50, and you will get the same 70 liters.

To get accurate data, you need to prepare:

• Calculator;
• Calipers;
• Ruler.

First, the radius, denoted by the letter R, is measured. It can be:

• internal;
• outdoor.

The outer radius is needed to determine the size of the space it will take.

For the calculation, you need to know the pipe diameter data. It is denoted by the letter D and calculated by the formula R x 2. The circumference is also determined. Designated with the letter L.

To calculate the volume of a pipe measured cubic meters(m3), you must first calculate its area.

To obtain an accurate value, you must first calculate the cross-sectional area.
To do this, apply the formula:

• S = R x Pi.
• The required area is S;
• Pipe radius - R;
• Pi is 3.14159265.

The resulting value must be multiplied by the length of the pipeline.

How to find the volume of a pipe using the formula? You need to know only 2 values. The calculation formula itself has the following form:

• V = S x L
• Pipe volume - V;
• Sectional area - S;
• Length - L

For example, we have a metal pipe with a diameter of 0.5 meters and a length of two meters. To carry out the calculation, the size of the outer cross member of the stainless metal is inserted into the formula for calculating the area of ​​a circle. The pipe area will be equal to;

S \u003d (D / 2) \u003d 3.14 x (0.5 / 2) \u003d 0.0625 sq. meters.

The final calculation formula will take the following form:

V \u003d HS \u003d 2 x 0.0625 \u003d 0.125 cu. meters.

According to this formula, the volume of absolutely any pipe is calculated. And it doesn't matter what material it's made of. If the pipeline has many constituent parts, applying this formula, you can calculate separately, the volume of each section.

When performing a calculation, it is very important that the dimensions are expressed in the same units of measure. It is easiest to calculate if all values ​​are converted to square centimeters.

If you use different units of measurement, you can get very questionable results. They will be very far from the real values. When performing constant daily calculations, you can use the calculator's memory by setting a constant value. For example, the number Pi multiplied by two. This will help to calculate the volume of pipes of different diameters much faster.

Today, for the calculation, you can use ready-made computer programs, in which, in advance, standard parameters. To perform the calculation, it will only be necessary to enter additional variable values.

Download the program https://yadi.sk/d/_1ZA9Mmf3AJKXy

How to Calculate Cross-Sectional Area

If the pipe is round, the cross-sectional area must be calculated using the formula for the area of ​​a circle: S \u003d π * R2. Where R is the radius (internal), π is 3.14. In total, you need to square the radius and multiply it by 3.14.
For example, the cross-sectional area of ​​​​a pipe with a diameter of 90 mm. We find the radius - 90 mm / 2 = 45 mm. In centimeters, this is 4.5 cm. We square it: 4.5 * 4.5 \u003d 2.025 cm2, we substitute in the formula S \u003d 2 * 20.25 cm2 \u003d 40.5 cm2.

The cross-sectional area of ​​a profiled product is calculated using the formula for the area of ​​a rectangle: S = a * b, where a and b are the lengths of the sides of the rectangle. If we consider the section of the profile 40 x 50 mm, we get S \u003d 40 mm * 50 mm \u003d 2000 mm2 or 20 cm2 or 0.002 m2.

Calculation of the volume of water present in the entire system

To determine such a parameter, it is necessary to substitute the value of the inner radius into the formula. However, a problem immediately appears. And how to calculate the total volume of water in the entire pipe heating system, which includes:

• Radiators;
• Expansion tank;
• Heating boiler.

First, the volume of the radiator is calculated. To do this, its technical passport is opened and the values ​​\u200b\u200bof the volume of one section are written out. This parameter is multiplied by the number of sections in a particular battery. For example, one is equal to 1.5 liters.

When installed bimetal radiator, this value is much smaller. The amount of water in the boiler can be found in the device passport.

To determine the volume expansion tank, it is filled with a pre-measured amount of liquid.

It is very easy to determine the volume of pipes. The available data for one meter, a certain diameter, simply needs to be multiplied by the length of the entire pipeline.

Note that in global network and reference literature, you can see special tables. They show indicative product data. The error of the given data is quite small, so the values ​​\u200b\u200bgiven in the table can be safely used to calculate the volume of water.

I must say that when calculating the values, you need to take into account some characteristic differences. Metal pipes with a large diameter pass the amount of water much less than the same polypropylene pipes.

The reason lies in the smoothness of the surface of the pipes. In steel products, it is made with a large roughness. PPR pipes do not have roughness on the inner walls. However, at the same time, steel products have a larger volume of water than in other pipes of the same section. Therefore, to make sure that the calculation of the volume of water in the pipes is correct, you need to double-check all the data several times and back up the result with an online calculator.

Internal volume of a running meter of a pipe in liters - table

The table shows the internal volume running meter pipes in liters. That is, how much water, antifreeze or other liquid (coolant) is required to fill the pipeline. The inner diameter of the pipes is taken from 4 to 1000 mm.

Inner diameter, mm	Internal volume of 1 m running pipe, liters	Internal volume of 10 m linear pipes, liters
4	0.0126	0.1257
5	0.0196	0.1963
6	0.0283	0.2827
7	0.0385	0.3848
8	0.0503	0.5027
9	0.0636	0.6362
10	0.0785	0.7854
11	0.095	0.9503
12	0.1131	1.131
13	0.1327	1.3273
14	0.1539	1.5394
15	0.1767	1.7671
16	0.2011	2.0106
17	0.227	2.2698
18	0.2545	2.5447
19	0.2835	2.8353
20	0.3142	3.1416
21	0.3464	3.4636
22	0.3801	3.8013
23	0.4155	4.1548
24	0.4524	4.5239
26	0.5309	5.3093
28	0.6158	6.1575
30	0.7069	7.0686
32	0.8042	8.0425
34	0.9079	9.0792
36	1.0179	10.1788
38	1.1341	11.3411
40	1.2566	12.5664
42	1.3854	13.8544
44	1.5205	15.2053
46	1.6619	16.619
48	1.8096	18.0956
50	1.9635	19.635
52	2.1237	21.2372
54	2.2902	22.9022
56	2.463	24.6301
58	2.6421	26.4208
60	2.8274	28.2743
62	3.0191	30.1907
64	3.217	32.1699
66	3.4212	34.2119
68	3.6317	36.3168
70	3.8485	38.4845
72	4.0715	40.715
74	4.3008	43.0084
76	4.5365	45.3646
78	4.7784	47.7836
80	5.0265	50.2655
82	5.281	52.8102
84	5.5418	55.4177
86	5.8088	58.088
88	6.0821	60.8212
90	6.3617	63.6173
92	6.6476	66.4761
94	6.9398	69.3978
96	7.2382	72.3823
98	7.543	75.4296
100	7.854	78.5398
105	8.659	86.5901
110	9.5033	95.0332
115	10.3869	103.8689
120	11.3097	113.0973
125	12.2718	122.7185
130	13.2732	132.7323
135	14.3139	143.1388
140	15.3938	153.938
145	16.513	165.13
150	17.6715	176.7146
160	20.1062	201.0619
170	22.698	226.9801
180	25.4469	254.469
190	28.3529	283.5287
200	31.4159	314.1593
210	34.6361	346.3606
220	38.0133	380.1327
230	41.5476	415.4756
240	45.2389	452.3893
250	49.0874	490.8739
260	53.0929	530.9292
270	57.2555	572.5553
280	61.5752	615.7522
290	66.052	660.5199
300	70.6858	706.8583
320	80.4248	804.2477
340	90.792	907.9203
360	101.7876	1017.876
380	113.4115	1134.1149
400	125.6637	1256.6371
420	138.5442	1385.4424
440	152.0531	1520.5308
460	166.1903	1661.9025
480	180.9557	1809.5574
500	196.3495	1963.4954
520	212.3717	2123.7166
540	229.0221	2290.221
560	246.3009	2463.0086
580	264.2079	2642.0794
600	282.7433	2827.4334
620	301.9071	3019.0705
640	321.6991	3216.9909
660	342.1194	3421.1944
680	363.1681	3631.6811
700	384.8451	3848.451
720	407.1504	4071.5041
740	430.084	4300.8403
760	453.646	4536.4598
780	477.8362	4778.3624
800	502.6548	5026.5482
820	528.1017	5281.0173
840	554.1769	5541.7694
860	580.8805	5808.8048
880	608.2123	6082.1234
900	636.1725	6361.7251
920	664.761	6647.6101
940	693.9778	6939.7782
960	723.8229	7238.2295
980	754.2964	7542.964
1000	785.3982	7853.9816

If you have a specific design or pipe, then the formula above shows how to calculate the exact data for the correct flow of water or other coolant.

Online calculation

http://mozgan.ru/Geometry/VolumeCylinder

Conclusion

To find the exact figure for the consumption of the coolant of your system, you will have to sit a little. Either search on the Internet, or use the calculator that we recommend. He might be able to save you time.

If you have a water-type system, then you should not bother and carry out an accurate selection of volume. It is enough to estimate approximately. An accurate calculation is needed more in order not to buy too much and minimize costs. Since many stop at choosing an expensive coolant.

The calculation of water consumption is made before the construction of pipelines and is integral part hydrodynamic calculations. During the construction of main and industrial pipelines These calculations are made using special programs. When building a domestic pipeline with your own hands, you can carry out the calculation yourself, but it should be borne in mind that the result obtained will not be as accurate as possible. How to calculate the water consumption parameter, read on.

Factors Affecting Throughput

The main factor by which the pipeline system is calculated is the throughput. On this indicator There are many different parameters, the most significant of which are:

1. pressure in the existing pipeline (in the main network, if the pipeline under construction will be connected to an external source). The calculation method taking into account pressure is more complex, but also more accurate, since it is pressure that determines such an indicator as throughput, that is, the ability to pass a certain amount of water in a certain unit of time;
2. the total length of the pipeline. The larger this parameter, the greater the number of losses manifested during its use and, accordingly, to eliminate the pressure drop, it is required to use pipes of a larger diameter. Therefore, this factor is also taken into account by specialists;
3. the material from which the pipes are made. If for a building or other highway are used metal pipes, then an uneven inner surface and the possibility of gradual clogging by deposits contained in the water will lead to a decrease in throughput and, accordingly, a small increase in diameter. Using plastic pipes(PVC) polypropylene pipes and so the possibility of clogging with deposits is practically excluded. What's more, the inner surface of plastic pipes is smoother;

1. section of pipes. According to the internal section of the pipe, you can independently make a preliminary calculation.

There are other factors that experts take into account. But for this article they are not essential.

Method for calculating the diameter depending on the cross section of pipes

If, when calculating the pipeline, it is necessary to take into account all of these factors, it is recommended to make calculations using special programs. If for the construction of the system it is enough preliminary calculations, they are carried out in the following order:

• preliminary determination of the amount of water consumption by all family members;
• count optimal size diameter.

How to calculate the water consumption in the house

Determine the amount of consumed cold or hot water in the house in several ways:

• according to the meter reading. If meters are installed when entering the pipeline into the house, then it is not a problem to determine the water consumption per day per person. Moreover, when observing for several days, you can get fairly accurate parameters;

• according to the established norms, determined by experts. The standard for water consumption per person is set for certain types of premises with the presence / absence of certain conditions;

• according to the formula.

To determine the total amount of water consumed in the room, it is necessary to make a calculation for each plumbing unit (bath, shower, faucet, and so on) separately. Calculation formula:

Qs \u003d 5 x q0 x P, Where

Qs is an indicator that determines the amount of flow;

q0 is the established norm;

P is a coefficient that takes into account the possibility of using several types of plumbing fixtures at the same time.

The q0 indicator is determined depending on the type of plumbing equipment according to the following table:

The probability P is determined by the following formula:

P = L x N1 / q0 x 3600 x N2, Where

L - peak water consumption for 1 hour;

N1 - the number of people using plumbing fixtures;

q0 - established standards for a separate plumbing unit;

N2 - the number of installed plumbing fixtures.

It is unacceptable to determine the water flow without taking into account the probability, since the simultaneous use of plumbing fixtures leads to an increase in the flow power.

Let's calculate water using a specific example. It is necessary to determine the water flow according to the following parameters:

• 5 people live in the house;
• 6 units of sanitary equipment are installed: a bathtub, a toilet bowl, a sink in the kitchen, a washing machine and a dishwasher installed in the kitchen, a shower cabin;
• peak water consumption for 1 hour in accordance with SNiP is set equal to 5.6 l / s.

Determine the size of the probability:

P \u003d 5.6 x 4 / 0.25 x 3600 x 6 \u003d 0.00415

We determine the consumption of oxen for the bath, kitchen and toilet room:

Qs (baths) = 4 x 0.25 x 0.00518 = 0.00415 (l/s)

Qs (kitchens) \u003d 4 x 0.12 x 0.00518 \u003d 0.002 (l / s)

Qs (toilet) \u003d 4 x 0.4 x 0.00518 \u003d 0.00664 (l / s)

Calculation of the optimal section

The following formula is used to determine the cross section:

Q \u003d (πd² / 4) xW, Where

Q is the amount of water consumed calculated by calculation;

d is the desired diameter;

W is the speed of water movement in the system.

By simple mathematical operations, it can be deduced that

d = √(4Q/πW)

W can be obtained from the table:

The indicators presented in the table are used for approximate calculations. To obtain more accurate parameters, a complex mathematical formula is used.

Let's determine the diameter of the pipes for the bath, kitchen and toilet according to the parameters presented in this example:

d (for the bathroom) \u003d √ (4 x 0.00415 / (3.14 x 3)) \u003d 0.042 (m)

d (for the kitchen) \u003d √ (4 x 0.002 / (3.14 x 3)) \u003d 0.03 (m)

d (toilet) = √(4 x 0.00664 / (3.14 x 3)) = 0.053 (m)

To determine the cross section of pipes, the highest design indicator is taken. Given the small margin in this example, it is possible to conduct water supply with pipes with a cross section of 55 mm.

How to calculate using a special semi-professional program, see the video.

Working with the calculator is simple - enter data and get the result. But sometimes this is not enough - an accurate calculation of the pipe diameter is possible only with manual calculation using formulas and correctly selected coefficients. How to calculate the diameter of the pipe according to the water flow? How to determine the size of the gas line?

When calculating the required pipe diameter, professional engineers most often use special programs that can calculate and give an accurate result using known parameters. It is much more difficult for an amateur builder to perform the calculation on his own to organize water supply, heating, gasification systems. Therefore, most often, when building or reconstructing a private house, the recommended pipe sizes are used. But not always standard advice can take into account all the nuances. individual construction, therefore, it is required to manually perform a hydraulic calculation in order to correctly select the diameter of the pipe for heating, water supply.

Calculation of pipe diameter for water supply and heating

The main criterion for selecting a heating pipe is its diameter. From this indicator depends on how effective the heating of the house will be, the life of the system as a whole. With a small diameter in the lines, increased pressure can occur, which will cause leaks, increased stress on pipes and metal, which will lead to problems and endless repairs. At large diameter the heat transfer of the heating system will tend to zero, and cold water will simply ooze from the tap.

pipe capacity

The diameter of the pipe directly affects the throughput of the system, that is, in this case, the amount of water or coolant passing through the section per unit time matters. The more cycles (movements) in the system for a certain period of time, the more efficient the heating. For water supply pipes, the diameter affects the initial water pressure - a suitable size will only maintain pressure, and an enlarged one will reduce it.

According to the diameter, a plumbing and heating scheme is selected, the number of radiators and their sectionality, and the optimal length of the mains is determined.

Since the throughput of the pipe is a fundamental factor when choosing, you should decide what, in turn, affects the permeability of water in the line.

Table 1. Pipe capacity depending on water flow and diameter

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

Factors influencing the patency of the highway:

1. The pressure of water or coolant.
2. The inner diameter (section) of the pipe.
3. The total length of the system.
4. pipeline material.
5. Pipe wall thickness.

On old system the patency of the pipe is aggravated by lime, silt deposits, the effects of corrosion (on metal products). All this together reduces the amount of water passing through the section over time, that is, used lines work worse than new ones.

It is noteworthy that this indicator polymer pipes does not change - plastic is much less than metal, allows slag to accumulate on the walls. So the throughput pvc pipes remains the same as on the day of installation.

Calculation of pipe diameter by water flow

Determining the right amount of water

To determine the diameter of the pipe by the flow rate of the passing liquid, you will need the values ​​\u200b\u200bof the true water consumption, taking into account all plumbing fixtures: a bathtub, a kitchen faucet, washing machine, toilet. Each is calculated separate plot plumbing according to the formula:

qc = 5× q0 × α, l/s

where qc is the value of water consumed by each device;

q0 is a normalized value, which is determined by SNiP. We accept for the bath - 0.25, for the kitchen faucet 0.12, for the toilet bowl -0.1;

a is a coefficient that takes into account the possibility of simultaneous operation of plumbing fixtures in the room. Depends on the probability value and the number of consumers.

In sections of the highway where the water flows for the kitchen and the bath, for the toilet and the bath, etc., are combined, the probability value is added to the formula. That is, the possibility of simultaneous operation of a kitchen faucet, bathroom faucet, toilet bowl and other appliances.

The probability is determined by the formula:

Р = qhr µ × u/q0 × 3600 × N,

where N is the number of water consumers (devices);

qhr µ is the maximum hourly water consumption that can be taken according to SNiP. Choose for cold water qhr µ =5.6 l/s, total consumption 15.6 l / s;

u is the number of people using plumbing.

Example of water consumption calculation:

IN two-story house there is 1 bathroom, 1 kitchen with installed washing and dishwasher, shower, 1 toilet. A family of 5 lives in the house. Calculation algorithm:

1. We calculate the probability P = 5.6 × 5 / 0.25 × 3600 × 6 = 0.00518.
2. Then the water flow for the bathroom will be qc = 5 × 0.25 × 0.00518=0.006475 l/s.
3. For the kitchen qc \u003d 5 × 0.12 × 0.00518 \u003d 0.0031 l / s.
4. For a toilet, qc = 5× 0.1 × 0.00518=0.00259 l/s.

We calculate the diameter of the pipe

There is a direct dependence of the diameter on the volume of the flowing liquid, which is expressed by the formula:

where Q is water consumption, m3/s;

d – pipeline diameter, m;

w is the flow velocity, m/s.

By transforming the formula, we can select the value of the diameter of the pipeline, which will correspond to the volume of water consumed:

Yulia Petrichenko, expert

d = √(4Q/πw), m

The flow rate of water can be taken from Table 2. There is a more complex method for calculating the flow rate - taking into account losses and the coefficient of hydraulic friction. This is a rather voluminous calculation, but in the end it allows you to get the exact value, unlike the tabular method.

Table 2. Fluid flow rate in the pipeline depending on its characteristics

Pumped medium		Optimum speed in the pipeline, m/s
LIQUIDS	Gravity movement:
	Viscous liquids	0,1-0,5
	Low viscosity liquids	0,5-1
	pumped:
	Suction pipeline	0,8-2
	Discharge pipeline	1,5-3
GASES	Natural traction	2-4
	Low pressure (fans)	4-15
	High pressure (compressor)	15-25
COUPLES	Overheated	30-50
	Saturated vapors at pressure
	More than 105 Pa	15-25
	(1-0.5)*105 Pa	20-40
	(0.5-0.2)*105 Pa	40-60
	(0.2-0.05)*105 Pa	60-75

Example: Calculate the diameter of the pipe for the bathroom, kitchen and toilet, based on the obtained water flow rates. We select from table 2 the value of the water flow rate in pressurized water supply– 3 m/s.