How to calculate water flow through a pipe by pressure and diameter

When laying water mains, it is most difficult to calculate the throughput of pipe sections. Correct calculations will ensure that the flow rate 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 the pipes of the selected section can supply. After all, if the pressure in the pipeline drops with large consumption, this will lead to the fact that it will be impossible to take a shower or bath normally. If a problem arises in a fire, you can completely lose your home. Therefore, the calculation of the patency of highways is carried out before the start of construction.

For small business owners, it’s also important to know the performance indicators. After all, in the absence of metering devices, utilities, as a rule, present an invoice for water consumption to organizations by pipe volume. Knowing the data on your water supply will allow you to control the flow of water and not pay too much.

What determines the pipe cross

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 throughput of pipe segments is a metric value that characterizes the volume of fluid passed through the line 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 throughput throughout the entire operational period. Plastic, in comparison with metal, does not rust, thanks to this the lines do not clog for a long time.

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

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

• The length of the water supply. The greater the length, the lower the flow rate due to the influence of the friction force, 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 the flow velocity to the value of the internal area in the fixed-length section will be. In wider pipelines, water moves faster.
• The presence of turns, fittings, adapters, cranes. Any fittings slow down the movement of water flows.

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

Calculation Methods

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

To determine the patency of the water supply system, you can use three calculation methods:

• The physical way. To clarify the indicators, formulas are used. Calculation requires knowledge of several parameters, in particular, the cross-sectional size of the pipe section and at what speed water moves in the mains.
• Tabular method. It is most simple, since by selecting indicators in the table, you can immediately find out the necessary data.
  

  Water Calculation Program
• Computer programming. Such "software" is easy to find and download on the Internet. It was created specifically for finding the patency of pipes of any system.To find out the necessary parameter, you need to enter the input data into the program: material, length, heat carrier quality.

The latter 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 home, you should resort to using an online calculator. Although it is not so accurate, it is free and does not need to be installed on a computer. More accurate information can be obtained by comparing the data calculated by the program with the table.

How to calculate throughput

The tabular way 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 circumference of the pipe.

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

Calculation of the temperature of the coolant

With an increase in temperature, the pipe passability decreases - the water expands and thereby creates additional friction.

You can calculate the necessary data using a special table:

For the plumbing system, this information is not extremely important, but for heating circuits it is considered the main indicator.

Pressure data search

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, the flow pressure in the common line must be taken into account. If a high-pressure head is provided, 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 large water flows are passed through small networks, they will begin to make noise, vibrate, and will quickly become worthless.

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

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. Pumping water through pumps also affects the change in flow rate.

Also, calculating the flow rate of water through the pipe according to the table of pipe diameter and pressure values, not only the number of taps, but also the number of water heaters, bathtubs and other consumers is taken into account.

Shevelev hydraulic calculation

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

As an example of a good sample for calculations, we can mention the Shevelev table. This is a comprehensive reference. To use it, it is not necessary to go to the library. All the necessary data can be found on the World Wide Web. In addition, there are electronic programs based on Shevelev tables. It is enough to enter the required parameters to get the finished result.

Application of formulas

The use of different formulas depends on known data. The simplest of them: q = π × d² / 4 × V. In the formula: q shows the flow rate of water in liters, d is the cross-section of the pipe in cm, V is the speed indicator of the hydroflow advance in m / s.

Speed ​​parameters can be taken from the table:

When connecting additional discharge devices, the coefficient of pressure created must be taken into account. It is listed in the user manual.

To know what characteristics pipes have, you need to correctly connect plumbing fixtures. With the correct selection of data there will be no reason to worry that when you open the faucet in the bathroom, the water in the kitchen will stop flowing or its pressure will decrease.