(1) Determination of liquid storage volume and liquid storage height of self-priming pump:
The liquid storage volume refers to the volume of the liquid part that can be stored in the pump body after the pump is stopped, that is, the volume of the pump body below the low point of the pump suction inlet. This volume is mainly part of the pressure chamber and the gas-liquid separation chamber. The liquid storage volume should not be less than half of the pump’s design flow rate in seconds [for example, the pump’s design flow rate, then the liquid storage volume should not be less than half of the pump’s design flow rate. If the liquid storage volume is too small [that is, there is too little liquid stored in the pump], This will increase the self-priming time and even make it impossible to self-prime; if it is too long, it will make the pump bulky. In addition to sufficient liquid storage volume, there must also be a certain liquid storage height. The liquid storage height is the height from the low point of pump suction to the center of the impeller, which is usually taken to be approximately equal to the radius of the impeller.
(2) Determination of the volume of the gas-liquid separation chamber and the height of the pump outlet:
Gas-liquid separation refers to the part of the pump body other than the pressure chamber. The larger the volume, the better the separation effect of gas and liquid, and the faster the separation. However, when the volume of the gas-liquid separation chamber is large enough, the increasing effect will be not obvious. On the contrary, it will make the pump body bulky. Therefore, the gas-liquid separation chamber has a volume value. According to existing experience, its value is equal to or slightly larger than the liquid storage volume. Under the condition of ensuring the capacity of the gas-liquid separation chamber, the pump body outlet reaches the height of the impeller centerline can be determined during drawing based on the liquid storage volume and the gas-liquid separation chamber volume.
(3) Determination of the gap between the septum tongue of the extrusion chamber and the impeller:
For centrifugal self-priming pumps, the gap between the partition tongue and the impeller has a great influence on the self-priming performance. The smaller the gap between the partition tongue and the impeller in the upper pressure chamber, the shorter the self-priming time. This gap is usually taken from the external mixing; internal mixing. If it is designed as a double scroll chamber, the gap between the lower press chamber tongue and the impeller can usually be determined according to the method of determining the clearance between the press chamber tongue and the impeller of a general centrifugal pump, that is, the lower partition tongue is located on the base circle of the scroll chamber.
(4) Determination of liquid flow rate in the extrusion chamber:
The flow rate of liquid in the discharge chamber of a centrifugal pump-type self-priming pump is lower than that of a general centrifugal pump, which is approximately equal to 80-90% of the flow rate of liquid in the discharge chamber of a general centrifugal pump.
(5) Area of return hole:
For internally mixed centrifugal self-priming pumps, the area of the return hole has a great influence on the self-priming performance. A large area causes more liquid to return to the impeller inlet through the return hole, so the self-priming time is short, but the self-priming vacuum degree is reduced; If the return hole area is small, the self-priming time will be long and the self-priming vacuum height will be high. Based on the above, when determining the return hole area, the requirements of self-priming time and self-priming height must be comprehensively considered.
(6) Turning of impeller rear cover plate:
For external mixing centrifugal self-priming pumps, when the outer circumferential speed of the impeller is less than . The turning amount cannot be too large, otherwise it will significantly reduce the lift and efficiency of the pump. At that time, the diameter of the impeller rear cover was cut; at that time, reinforcement was added to the upper partition tongue to prevent liquid with bubbles from circulating at the cut back cover and affecting the self-priming effect.
Therefore, Sunpace Pumps reminds you that when choosing a self-priming pump, users must have a certain understanding of the transmission medium, the actual installation situation, and the performance technical indicators and structure of the self-priming pump. Choose a suitable self-priming pump correctly and reasonably. Self-priming sewage pump is an efficient, energy-saving and environmentally friendly product for sewage treatment.
The above is what Sunpace Pumps has shared with you. We hope it will be helpful to you.