First, the auxiliary impeller fluid power sealing technology

The so-called auxiliary impeller is in fluid power seals the rear cover of the pump impeller coaxial opposite direction near the back of an open impeller installed. When the pump is working, together with Vice-impeller with the pump shaft rotation, the liquid will associate with the impeller rotation, rotation of the liquid will produce an outward centrifugal force, the centrifugal force on the one hand the flow of mechanical seals to withstand the liquid, reducing the mechanical seal pressure. On the other hand to prevent the media of solid particles into the mechanical seal friction, reducing wear on mechanical seal grinding blocks, extending its life.

Play a role in addition to auxiliary impeller seal, but also may help reduce the role of axial force in the submersible sewage pump is mainly in the axial force acting on the impeller on the liquid pressure force and the rotating part of the gravity of the composition of this The role of the two forces is the same direction, efforts made by the sum of two forces. Can be seen in the case of exactly the same performance parameters, submersible sewage pump horizontal pump axial force is larger than the average, while the balance of difficulty is harder than the vertical pump. Therefore, sewage pump, the bearings are also easy to damage the cause of a large axial force and have a great relationship.

If installed, Vice impeller, the impeller on the liquid pressure acting on the Vice-direction of the force is the force of the two opposite forces, which can offset part of the axial force, also played a role in extending bearing life. But the use of auxiliary impeller sealing system also has a drawback, that is to be consumed in the auxiliary impeller Shang part of the energy, generally around 3%, but if properly designed, can this part of the losses to a minimum.

Second, the pump design without the application of overload

Centrifugal pumps in general, the power is always increased with increasing flow, that is, the power curve with the flow rate is increased with a curve, which will bring the pump with a question: When the pump design operating point operation, in general, the pump power is less than the motor rated power, the use of this pump is safe; but when the pump head decreases, the flow rate will increase (from the pump performance curve can be seen) power also increases.

When the traffic flow exceeds the design operating point and to reach a certain value, the pump motor input power may exceed the motor rated power overload caused by burning. Motor overload protection system running either the pump stops operation; or burn the motor protection system failure.

Head lower than the design of the pump operating point lift usage in practice is often encountered, a situation is in the pump selection, pump head selected too high, but the actual use is to lower the lift pump use; the other is in use the pump to determine the operatingpoint is not very good, in other words the pump flow require frequent adjustment; there is a need for frequent changes is the pump locations. Three cases were unfamiliar overload may affect the pump's use of the pump. It can be said, not all head for the pump characteristics (including submersible sewage pumps), its use will be largely limited.

Characteristics of the so-called total head (also called No-overload characteristics) is the power curve increase with increasing flow speed is very slow, even better is when the flow increased to a certain value, the power not only will not increase, but will be down, which means the power curve there is a hump in the curve, and if so, we just select the motor rated power just over the hump point value, then the maximum flow rate in the 0 traffic to the entire range, both in the one you operating point on the run, the pump will not exceed the power leaving the pump motor power overload, with this performance for the pump, whether it is selection or use, will be very convenient. Also equipped with electrical power and need not too large, can save considerable cost of equipment.