Mechanical rubber sealing ring sealing devices are mainly divided into two categories: static sealing and dynamic sealing. Static sealing usually includes gasket sealing, O-ring sealing, thread sealing, and other forms. Dynamic seals mainly include soft packing seals, oil seal seals, labyrinth seals, spiral seals, power seals, and mechanical seals.

There are two main reasons for leakage: first, there are gaps on the sealing surface. The second is that there is a pressure difference on both sides of the sealing part. Eliminating or reducing any factor can prevent or reduce leakage, achieving the purpose of sealing. The design pressure and operating pressure of the pump cannot be reduced objectively, so the sealing of the pump should solve the problem of eliminating or reducing the gap between the sealing surfaces. This type of gap includes the gap between sealing surfaces and the gap inside the sealing device itself.

Mechanical rubber seal ring sealing is the main method for modern pump shaft sealing. Although it is not easy to achieve complete no leakage using it, it is completely possible to achieve a small and completely acceptable leakage amount. But embarrassing situations often occur during mechanical operation, so what are the reasons for the failure of mechanical rubber sealing rings?

1. The material selection of mechanical rubber sealing rings is not appropriate.

The material of the mechanical rubber seal ring does not match the medium being transported. During operation, sealing components are quickly corroded, dissolved, or worn, resulting in a loss of sealing ability. Therefore, selecting the material of the mechanical seal based on the properties of the conveying medium is a prerequisite for ensuring its sealing function and normal service life.

2. The flushing condition of the mechanical rubber sealing ring does not meet the design requirements.

When conveying media that are prone to crystallization or have small particles, a certain pressure and flow rate of flushing solution must be used for flushing. Otherwise, the crystallization or particles will accelerate the wear of the sealing pair and affect the automatic compensation after the wear of the sealing pair, leading to leakage. Therefore, according to the properties of the conveying medium, it is not only necessary to configure corresponding flushing pipelines, but also to install instruments and devices with monitoring and adjustment functions to ensure that the pressure and flow rate of the flushing fluid meet the design requirements in order to maintain the normal operation of the machine seal, which is often overlooked by users.

3. The working pressure of the mechanical rubber seal ring exceeds the bearing value.

The pressure that each type of mechanical rubber sealing ring can withstand is limited. Due to inaccurate calculation of the pressure inside the sealing chamber, the pressure inside the sealing chamber exceeds the pressure that the mechanical rubber sealing ring can withstand, resulting in leakage. This is also one of the common causes of sealing failure.

4. The working temperature of mechanical seals cannot exceed its specified value.

In the design of cooling pipelines, the cooling effect is often reduced due to insufficient flow rate of the cooling medium; In designs without cooling pipelines, the mechanical seal is often in a dry friction state due to the presence of trapped air in the sealing chamber. Both of these situations can cause the working temperature of the motion seal pair of the mechanical seal to be too high, accelerating wear and leading to seal failure.

5. When using a single spring mechanical seal, it is common to overlook the correct combination of the spring's rotation direction and the pump rotor's rotation direction. Or there was no explanation during design, or negligence during assembly, which did not increase the spring force of the mechanical seal due to the rotation of the rotor, but instead caused insufficient pressure on the friction pair of the dynamic and static rings, resulting in leakage.

6. Severe wear or damage to bearings can cause severe axial displacement of the pump shaft, which is also one of the reasons for mechanical seal leakage. With the development of science and technology, new sealing forms and sealing materials have emerged one after another, which will inevitably have a direct impact and promotion on the sealing technology of pumps. Pump products with long lifespan and zero leakage will be promoted and applied in more and more occasions.