Pressure loss in PVC pipe fittings

How to calculate the pressure loss in the PVC pipe?

The pressure loss in pipeline is divided into pressure loss and partial pressure loss.

Pressure loss along the path Pf= ([lambda L/d) P V^2/2

Local pressure loss Pj= sigma zeta Rho V^2/2

The total pressure loss in pipes is Pw=Pf+Pj= (lambda L/d) V^2/2+, V^2/2=[, (V^2/2) + V^2/2.

In the formula: the drag coefficient of the lambda pipe; L - pipe length; D - pipe diameter; Sigma - total number; Zeta - pipe local resistance coefficient; P - fluid density; V - pipe flow velocity.

For long pipes, the local pressure loss can be ignored. The total pressure loss in pipes is Pw=Pf = (lambda L/d) V^2/2

Or Pw = Rho gsLQ^2

Formula: P - fluid density; G - gravity acceleration; s - pipe specific resistance; L - pipe length; Q - pipe flow.

The relationship between specific resistance and drag coefficient of pipeline: s=8 lambda / (g PI ^2d^5)

Lambda and s can be used to check hydraulic calculation manuals.

The calculation of pressure loss is actually the summation of the resistance loss of pipelines.

The PVC pipe is divided into local resistance and drag resistance: 1, the local resistance is formed by the pipe accessories (elbow, three pass, valve, etc.). It is proportional to the coefficient of the local resistance and the dynamic pressure. The local resistance coefficient can be derived from the type of the appendix and the size of the opening according to the manual. The dynamic pressure is proportional to the square of the velocity. 2. The resistance along the line is proportional to the frictional resistance multiplied by the length of the pipe, and the specific friction is determined by the diameter of the pipe, the roughness of the inner wall and the velocity of the fluid.

In a word, the size of pipe resistance is related to the average velocity of the fluid, the viscosity of the fluid, the size of the pipe, the length of the pipe, the liquid gas liquid, and the smoothness of the inner wall of the pipe. It is complicated in computation, various in classification and large in error. If we want to understand it, we should learn "fluid mechanics", if it is difficult to understand it.

How to calculate flow pressure in PVC pipeline

The flow pressure of the pipe is related to the pressure of the water source at the end of the pipe. The pressure is changed during the flow of the pipe. The pressure on a section on the pipe must be calculated by the Bernoulli energy equation, and the pressure loss of the pipe must be considered. For straight equal diameter pipes, the pressure loss of PVC pipe with a length of L can be calculated by the following formula.

Delta P= (lambda L/d) Rho V^2/2

Lambda - PVC pipeline resistance coefficient; L - PVC tube length; D - PVC tube inner diameter; P - water density; V - pipe flow rate.

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