In order to facilitate the majority of users to determine the pipeline pressure loss when the pump is selected, Zoomlian technical engineers released the pipeline pressure loss calculation formula for everyone to choose.
Through the pump performance curve, it can be seen that each pump has its own performance curve at a certain speed. The performance curve reflects the potential working capacity of the pump itself. This potential working capacity is reflected in the actual operation of the pump station. For actual working ability under certain conditions. The operating point of the pump depends not only on the performance of the pump itself, but also on the performance of the piping system of the inlet and outlet water levels and the inlet and outlet pipes.
Therefore, the operating point is determined by the performance of the pump and piping system. The piping system of the pump, including the piping and its accessories. It is known from hydraulics that pipeline head loss includes head loss and local loss along the pipeline. Σh=Σhf+Σhj=Σλι/d v2/2g+Σζv2/2g (3-1) where Σh—pipe head loss, m; Σhf—the head loss along the pipeline, m; Σhj—the local head loss of the pipe, m; λ-- drag coefficient along the path; ζ--local head loss coefficient; ι--pipe length, m; d--pipe diameter, m; v - average flow rate of water flow in the pipe, m/s.
For the circular tube v=4Q/πd2, the equation (3-1) can be written as the following form Σh=(Σ λι/12.1d5+Σ ζ/12.1d4) Q2=(ΣS along +ΣS bureau)Q2=SQ2 (3- 2) In the formula S--the resistance coefficient along the pipeline, S2/m5, when the pipe, pipe length and pipe diameter are determined, the value of ΣS is a constant; S--the local resistance coefficient of the pipe, S2/m5, when After the pipe diameter and local head loss type are determined, the value of ΣS is a constant; S--the sum of the pipeline along the local resistance coefficient, S2/m5. It can be seen from equation (3-2) that the head loss of the pipeline is proportional to the square of the flow rate. Equation (3-2) can be represented by a quadratic parabola at the origin, which reflects the head loss and tube of the pipeline. The law of the passage of the road through the flow is called the pipeline head loss characteristic curve.
As shown in 3-1. In the design and operation management of the pumping station, in order to determine the operating point of the self-priming device, the pipeline head loss characteristic curve can be utilized and linked to the external conditions of the pump operation. Thus, the energy H required for the unit gravity liquid to pass through the pipeline system is H needs = Hst + v2 - v2 into / 2g + Σ h (3-3) where H is required - the required head of the pump device, m; Hst--the net head when the pump is running, m; v2 out - v2 into / 2g - the flow rate of the inlet and outlet water head difference, m; Σh--pipe head loss, m. If the head difference of the flow rate of the inlet and outlet tanks is negligible, then the formula (3-3) can be simplified to H. = Hst + Σ h = Hst = SQ2 (3-4) The formula (3-4) can be drawn. As shown in 3-2, the secondary parabola, any point on the curve indicates the energy consumed by each gravity liquid in the pipeline when the pump delivers a certain flow rate and raises it to the Hst height. Therefore, the curve is referred to as the required head or piping system characteristic curve of the water pump device.
