Mechanical seal selection guide1

I. Instructions for the selection of mechanical seals

Each type of mechanical seal can only be used effectively within the specified range. Improper selection will lead to a significant reduction in sealing performance, shortened life, and even failure. The main parameters of the selection are as follows:

1. Seal chamber medium pressure P

P≤0.8MPa, choose unbalanced type, P≥0.5MPa, choose balanced type.

2. Linear speed V

The linear velocity should be combined with pressure, temperature, medium characteristics, etc. to determine the spring form.

3. The PcV value relates to the stability (vaporization) of the fluid film between the sealing surfaces and the wear resistance of the friction pair.

4. In the absence of external cooling, the maximum operating temperature of the mechanical seal generally depends on the safe operating temperature of the auxiliary sealing material.

5. The specificity of the medium

Some media have special requirements for auxiliary seals. For example, fluorine rubber cannot be used for media such as solvents, and EPDM rubber cannot be used for mineral oil. Users should pay special attention to: Balanced type should be selected for low-viscosity media that are prone to dry friction. , High viscosity medium should use forced transmission structure. Strong corrosion should be sealed with an externally mounted PTFE bellows.

Customers can also provide relevant data and materials to our factory, and we will select the most suitable products for you or design and manufacture them for you. Relevant data and information should include: equipment name, shaft diameter, speed; medium name, pressure, temperature, concentration, viscosity, presence or absence of particles.

Second, the technical requirements for mechanical seals in accordance with and use

1. The radial runout of the main shaft where the seal is installed should be ≤0.04mm (0.06mm), and the axial movement amount should be ≤0.3mm, and the corresponding parts of the machining shaft and the static ring seat should be installed according to the standard requirements.

2. The sealing cavity, shaft and mechanical seal parts should be cleaned, and there should be no pollution, bumps, scratches, especially to prevent impurities, dust and particles from being brought into the sealing cavity.

3. During installation, it is strictly forbidden to collide and beat violently, and the surface of the friction pair should be absolutely clean.

4. The static ring gland must have sufficient strength, and tighten the screws evenly during installation to ensure that its end face is perpendicular to the axis.

5. After installation, lightly press the moving ring by hand, it should be flexible and flexible, and the manual crank should run freely.

6. Perform a static pressure test to observe for leaks.

7. Start the test run, pay attention to whether there is any abnormal sound

8. When the operating temperature exceeds 80°C, forced circulation should be adopted to cool the seal.

9. The sealed pipeline must be kept unobstructed, and dry friction is strictly prohibited.