What are the technical requirements for V-shaped sealing rings and other components

V-shaped sealing ring is a typical form of lip sealing ring. It is widely used like O-ring. It is used more in process pumps mechanical seals. Most V-shaped rings are made of polytetrafluoroethylene material, which can make up for the vinyl fluoride material because it has such defect of insufficient elasticity.

V-shaped sealing ring always consists of two parts: V-shaped ring and support ring (push ring, pressure ring). Under the action of medium pressure and spring force, the support ring spreads the two lips of the V-shaped ring, making the V-shaped ring close to the cover to achieve sealing. When used for rotary faces of mechanical seals, two V-shaped rings are often used, and a metal push ring (pressure ring) is used instead of the support ring.

According to experiments, the number of overlapping V-shaped rings should not exceed 3, otherwise the friction resistance will increase sharply, which will be detrimental to the sealing ring of the mechanical seal.

The PTFE V-ring has excellent corrosion resistance, but it cannot return to its original shape after being deformed by heat and pressure. It has cold flow, is easy to wear, and has large thermal expansion. For this reason, fillers are often added. In order to reduce wear, the surface roughness at the contact point with the sealing ring of the mechanical seal should be improved as much as possible.

The shape of the V-ring is shown in the picture below, and the dimensions are shown in the table 1 below.

The assembly interference of the inner and outer diameter of the V-ring is within the range of 0.05-0.5mm. The non-perpendicularity to the center line drawn on this end of the V-shaped ring of the mechanical seal should be less than 0.02mm, and the surface roughness should not be less than Ra3.2 (▽6).