At present, the commonly used seals of Bonve stainless steel rotary lobe pumpare mechanical seal type. According to the design form, the mechanical seal are divided into single-face and double-face, and according to different design concepts, they are divided into balanced and unbalanced mechanical seal. Here we mainly introduce the balanced mechanical seal.

The main components of the mechanical seal whether it is a single-face or a double-face are the moving ring, the stationary ring, the sealing strip, the pressure spring, etc. The difference is that the moving ring and stationary ring of single-face are contact via one surface, while the moving ring and stationary ring of double-face are contacting via two surfaces. The mechanical seal relies on the stationary ring fixed on the pump case and the axial force such as the sealing fluid and the spring force to make the two surface of the moving ring fixed on the shaft or sleeve tightly fit and rotate with each other. The tight fit creates a tiny gap between the sealed surface. There will form a very thin liquid film to generate resistance, preventing medium leakage and lubricating the double-face to ensure its sealing when organic seal water passes through the gap. Due to the double-face closely fit and rotate, the machining accuracy of the face is required to be high. The commonly used contact material for mechanical seal of Bonve Rotary Lobe Pump is tungsten carbide and silicon carbide. The tungsten carbide is mainly used for high viscosity liquids and chemical products. The silicon carbide is mainly used for food, daily chemical and other products.

Pump mechanical seals are different from packing seals. The mechanical seals are precision parts and require strict manufacturing accuracy, installation accuracy and pump accuracy. If one of them fails to meet the requirements, it will directly affect the sealing performance and service-life of mechanical seal.

The installation requirements of the mechanical seal are as follows:

• The new mechanical seal should be guaranteed not to be knocked, bumped, or violently oscillated. When install, it should not be savagely beaten and mechanical seal is clean.
• Should check the all parts surface when installing the mechanical seal, especially whether the sealing surface of moving ring and stationary ring is bumped or scratched. If it is damaged, it must be repaired or replaced. The surface of parts must be cleaned or wiped clean, and a layer of engine oil should be applied to the surface of the sealing rubber ring. (Note: the rubber ring of ethylene propylene, butyl and other materials should not be in contact with oil or grease, try to use animal oil or soap, washing liquid to lubricate.)
• After installation, it should be turned by hand according to rotation direction of the shaft to observe if the rotation is flexible. If abnormal, it must be adjusted.
• When using double-face mechanical seal, the water pressure of the machine seal must be greater than the pressure of the medium 0.1-0.2MPa.

How to improve service-life of mechanical seals?

The mechanical seal damage is generally caused by improper installation, wrong material selection, large pressure fluctuations, and unqualified water pressure of the mechanical seal.

In view of the above situation, we can start from the following aspects:

• Install the mechanical seal correctly;
• Maintain the other parts of pump to reduce the beating;
• Add a pressure gauge  to the water inlet of mechanical seal to observe water pressure;
• Improve the water quality of mechanical seal cooling water;
• Operate correctly, turn on the equipment after 5 minutes each time the flushing water or cooling water is turned on, and stop the flushing water or cooling water after 5 minutes each time the equipment is stopped.

In order to improve the service life of mechanical seals, Bonve organizes technical teams to provide installation technical guidance to workers every month; quality inspectors carefully inspect the products before leaving the factory; go to the customer site to analyze materials to select the most suitable mechanical seal type; even invest a lot of financial and manpower to develop the most suitable mechanical seal for each application.

Any interest to learn more about Bonve stainless steel rotary lobe pump, pls click the below pump photo.