The flow rate, that is, the amount of liquid delivered per unit time, is most commonly used in m3/h, which is the number of squares that are often said.
If the design institute gives the normal, minimum, and maximum three types of traffic, the maximum flow rate is selected based on the normal flow rate. When there is no maximum flow rate, 1.1 times the normal flow rate can be taken as the maximum flow rate.
If there is no design company calculation, you can divide the amount of infusion required per day by the pump start time. For example, if you need to transport liquid 80-100 squares per day and the boot time is 10 hours, then the pump flow range is 8-10m3/h.
The flow rate of the pump refers to the volume or mass of the liquid pumped out by the pump for a certain period of time, which is called volume capacity and masscapacity. The volume flow is usually represented by the letter symbol Q, and the flow unit of the pump. There are m3/s (cubic/second), L/S (liter/second), or M3/h (cubic/hour), and the conversion relationship between them is: 1m3/s=1000L/s=3600m3/h. The mass flow rate is expressed by Qm, and the unit of mass flow is commonly used in kilograms per second (kg/s) or tons per hour (t/h). By definition, the relationship between volume flow and mass flow: Qm = pQ, where p is the density of the liquid being transported (kg/m3). Due to the different flow requirements of various applications, the vane pump design flow range is very wide, less than 1 liter per second, and large is tens or even hundreds of cubic meters per second.
The flow rate indicated on the sign when the pump is shipped is the rated flow of the pump, that is, the intermediate value of the flow. The pump works most efficiently under this flow data. If it deviates from this flow during use, then the pump The efficiency will be greatly reduced. If the deviation is too much, the motor will burn out. For example, the rated flow of a pipeline centrifugal pump is 100m3/h. In actual use, the flow rate of the pump is preferably controlled in this data, if the pump When the flow rate exceeds 120m3/h, special attention should be paid to whether the motor current has exceeded the current data indicated on the pump nameplate. If the super-flow operation is performed, the opening of the pump outlet valve should be used to control the flow rate of the pump in the rated flow range. In-house operation, in order to save energy and reduce the cost of use, the flow rate of the pump should be run as far as possible under the designed flow conditions.
What is the pump flow calculation formula?
In the process of using the pump, it is often necessary to calculate the pump flow, but many people do not know the pump flow calculation formula. Below, Changsha Zhonglian Pump Industry takes the submersible pump and gear pump as an example to introduce the pump flow calculation formula in detail. The volume of liquid discharged by the pump per unit time is called flow, and the flow rate is expressed by Q. Unit of measurement: cubic meter / hour (m3 / h), liter / sec (l / s), L / s = 3.6 m3 / h = 0.06 m3 / Min=60L/minG=Qρ G is the weight ρ is the liquid specific gravity.
The shaft power (kw) of the pump = water supply (liter / sec) × head (m) / 102 × efficiency = flow × head × density × gravity acceleration. 102 is a unit finishing constant. Pump effective power / pump shaft power = pump efficiency (generally 50% - 90%, large pump is higher) The energy obtained by the pump per unit weight of liquid is called the lift. The lift of the pump, including the suction stroke, is approximately the difference between the pump outlet and the inlet pressure. The lift is indicated by H and the unit is meters (m). The efficiency of the pump refers to the ratio of the effective power of the pump to the shaft power. The power of the η=Pe/P pump usually refers to the input power, that is, the power that the prime mover transmits to the pump shaft, so it is also called the shaft power, which is denoted by P. The effective power is the product of the pump head and mass flow and gravity acceleration. Submersible pump flow calculation formula: 60HZ flow × 0.83 = 50HZ flow 60HZ lift × 0.69 = 50HZ lift 60HZ power ÷ 1.728 = 50HZ motor power motor output power = Q (flow) × H (head) / 367.2 / efficiency × 1.15 motor output power = shaft power × 1.15 pump efficiency = Q × H × 0.00272 / motor power Q represents flow; H represents the head; 0.83 / 0.69 / 1.728 / 367.2 / 1.15 / 0.00272 are all coefficients. The gear oil pump flow calculation formula is: | Z——number of teeth; n——number of revolutions, revolutions/minutes; ηv——volume efficiency, for general gear oil pumps, the value can be taken as 0.70~0.90; q——the volume of the pit between the two teeth, cubic meters.
Causes and troubleshooting methods for insufficient pump flow
The power speed is not matched or the belt is slippery, so the speed is low; the axial pump blade installation angle is too small; the head is insufficient, the pipeline is too long or the pipeline has a right angle bend; the suction stroke is high; the bottom valve, the pipeline and the impeller are partially blocked. Or impeller defect; the outlet pipe leaks seriously.
Remedy: restore the rated speed, remove the belt grease, adjust the belt tightness; adjust the blade angle, reduce the pump installation position, shorten the pipeline or change the bending of the pipeline; seal the pump leakage, compact the packing; clear the blockage Replace the impeller; replace the leak-reducing ring and block the leak.
