How to choose the appropriate diameter of PPR pipes?

Calculation of Flow Rate: First, determine the expected flow rate of the fluid (usually water) through the pipe. The flow rate depends on the number of fixtures (such as faucets, showers, toilets) that will be supplied by the pipe and the rate at which water is used in each fixture. For example, a standard faucet may have a flow rate of about 0.2 - 0.3 liters per second, while a showerhead can have a flow rate of around 0.1 - 0.15 liters per second per nozzle.

Matching with Pipe Capacity: PPR pipes have different flow capacities depending on their diameter. As a general rule, larger - diameter pipes have a higher flow capacity. For instance, a 20 - mm - diameter PPR pipe may have a maximum flow rate of around 0.3 - 0.4 liters per second under normal pressure conditions, while a 25 - mm - diameter pipe can handle approximately 0.5 - 0.7 liters per second. You need to ensure that the chosen pipe diameter can meet the total flow rate requirements of all the connected fixtures without causing excessive pressure drops.

System Pressure: Consider the pressure of the water supply system. Municipal water supplies usually have a certain pressure range, typically between 2 - 6 bar. In a building's internal water distribution system, pressure may vary due to factors such as the height of the building and the length of the piping network. If the pressure is high, a larger - diameter pipe may be needed to reduce the velocity of the water and the resulting pressure losses.

Pressure Drop: As water flows through a pipe, there is a pressure drop due to friction against the pipe wall. The pressure drop is inversely proportional to the fifth power of the pipe diameter. That means a small increase in diameter can significantly reduce the pressure drop. For example, if you have a long - running pipe or a system with multiple bends and fittings, choosing a slightly larger - diameter pipe can help maintain an acceptable pressure at the end of the line.

Length of the Pipe: The longer the pipe run, the more resistance there will be to flow, and the greater the potential for pressure drops. For a long - distance water supply (such as from a well to a house), it is often beneficial to choose a larger - diameter pipe to compensate for the resistance. For example, if the pipe run is more than 50 meters, increasing the diameter by 5 - 10 mm compared to a shorter run may be a good option.

Complexity of the Layout: If the piping system has many bends, elbows, and fittings, the resistance to flow increases. In such cases, a larger - diameter pipe can help to reduce the overall impact of these fittings on the flow rate and pressure. Each fitting also causes a certain amount of pressure loss, and a larger - diameter pipe can offset some of this loss.

Anticipated Changes: Consider whether there will be any future expansion of the water - using facilities. If you plan to add more fixtures (such as an additional bathroom or a new kitchenette), it is advisable to choose a pipe diameter that can accommodate the increased flow rate requirements. For example, if you are building a house and expect to expand the second floor in the future, it may be better to install pipes with a diameter that can handle the additional water demand.

Load Capacity Margin: It's also a good idea to have a margin of load capacity. Choosing a pipe diameter that is slightly larger than the current minimum requirement provides a buffer for unexpected changes in water usage patterns, such as an increase in the number of people using the water system or a change in the type of water - using equipment (e.g., installation of a high - flow - rate showerhead).