Shaft Seal In Pump

Dynamic seals can be divided into two categories: back blade seals and auxiliary impeller seals. When the pump is working, the centrifugal force of the back blade (or auxiliary impeller) causes the medium pressure at the shaft seal to drop to normal pressure or negative pressure, so that the pump does not leak during use. When the pump is stopped, the centrifugal force disappears, and the sealing effect of the back blade (or auxiliary impeller) fails. At this time, the parking seal device plays a sealing role. Packing seals are more commonly used in the parking seal device matched with the back blade (or auxiliary impeller). There are two types of packing seals: ordinary and mechanical loose-tight.Ordinary packing seals are similar to general packing seal pumps, requiring a slight positive pressure at the shaft seal to avoid dry friction of the packing. Mechanical loose-tight packing seals use counterweights to loosen the packing when the pump is running and tighten the packing when it is stopped. Dynamic seals have reliable performance, low price, and easy maintenance. They are suitable for conveying media containing more solid particles, such as slurry pumps and slurry pumps in the phosphoric acid industry. The disadvantage is that the power loss is greater than that of mechanical seals, and the life of its parking seal device is shorter. The seal between the rotating pump shaft and the fixed pump housing is called a shaft seal. Its function is to prevent high-pressure liquid from leaking out of the pump along the shaft, or outside air from penetrating along the shaft. For the shaft seal of a centrifugal pump, it is a dynamic seal. According to whether the sealing surfaces are in contact, it can be divided into contact dynamic seals and non-contact dynamic seals. The sealing device of the contact dynamic seal is in contact with the shaft, and there is relative friction between the two. Contact dynamic seals include packing seals, mechanical seals, and