Learn - Apr. 13, 2021
In normal conditions, common centrifugal pumps are unable to evacuate the air from an inlet line leading to a fluid level whose geodetic altitude is below that of the pump. Self-priming pumps have to be capable of evacuating air (see Venting) from the pump suction line without any external auxiliary devices.
Centrifugal pumps with an internal suction stage such as water jet pumps or side channel pumps are also classified as self-priming pumps.
Centrifugal pumps which are not designed with an internal or external self-priming stage can only start to pump the fluid after the pump has initially been primed with the fluid. In addition, a suction-side swing check valve or a vent valve must be fitted to prevent any siphon action and ensure that the fluid remains in the casing when the pump has been stopped. In self-priming centrifugal pumps with a separation chamber the fluid pumped and the entrained air bubbles are pumped into the separation chamber by the impeller action
The air escapes through the pump discharge nozzle whilst the fluid drops back down and is once more entrained by the impeller. The suction line is thus continuously evacuated. The design required for such a self-priming feature has an adverse effect on pump efficiency. Also, the dimensions of the separating chamber are relatively large. For these reasons this solution is only adopted for small pumps, e.g. garden pumps. More frequently used types of self-priming pumps are side channel and water ring pumps. Another type of self-priming pump is a centrifugal pump with two casing chambers and an open impeller. This design is not only used for its self-priming capabilities but also for its degassing effects when pumping twophase mixtures (air/gas and liquid) for a short time in process engineering or when handling polluted fluids, for example when draining water from construction pits.
This pump type operates without a foot valve and without an evacuation device on the suction side. The pump has to be primed with the fluid to be handled prior to commissioning.
The IHF Fluoroplastic Plastic lining pump is designed according to international standards. The pumping housing is made of metal outing lined with fluoroplastics/PTFE/PFA/F46/PVDF/Teflon, and the impeller and pump cover are pressed into form with metal inserts wrapped by fluroplastic/PTFE/PFA/F46, and the shaft seal is realized by mechanically.
The FZB series FFA/PTFE/FEP plastic self-priming pump is designed according to international standards and China National Standard. All flow components are lined with FFA/PTFE/FEP, and the load bearing part of the pump is made of metal. Can be equipped with external single-face mechanical seals, external container-type mechanical seals with flushing.
Diesel Self-Priming Pump
Trailer mounted Self Priming Centrifugal pump integrates self-priming and non-blocking sewage. It adopts axial reflow and external mixing, and through the unique design of pump body and impeller flow channel, it can be installed like the general self-priming pump. It has the characteristics of simple structure, good self-priming performance, strong sewage discharge capacity, high efficiency and energy saving, convenient use and maintenance, etc. The diesel engine and the self-priming pump are perfectly combined and can be manually set. , automatic control.There are various materials available for self-priming pump, including stainless steel SS304, SS316, SS316L, 904L, duplex stainless steel CD4MCu, 2205, 2507, Alloy 20, Hastelloy, Titanium, Monel, Nickel.
