How to Select Packing Materials?

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Typical Sealing Applications: How to Select Packing Materials?

Today, we will discuss the selection of packing materials. Choosing the right packing material involves multiple factors. First, the appropriate type of packing should be selected based on the requirements of the separation process. At the same time, various factors such as process requirements, material properties, and cost need to be considered comprehensively.

Basic Requirements for Packing Materials

1. Temperature Adaptability

This refers to heat resistance, which is often evaluated by measuring thermal loss.

2. Medium Resistance

Whether the sealing medium causes corrosion, oxidation, or other chemical reactions to the packing material.

3. Pressure Resistance

The packing material must possess high elasticity and compressibility, with minimal permanent deformation.

4. Intrinsic Tightness

The material itself should have good sealing performance, or show improved tightness after being compressed.

5. Low Friction Coefficient and Good Wear Resistance

Whether for valve stem packing or pump shaft packing, there will be relative motion between the packing and the sealed surface (such as the valve stem or pump shaft). Therefore, the packing material should have a low friction coefficient and good wear resistance under these conditions.

6. Chemical Stability

Packing materials should be chemically stable toward both the metal surfaces and the working medium. They should cause minimal contamination to the medium and maintain stability during operation.

7. Environmentally Friendly

Packing materials should also be environmentally friendly and safe for use.

Key Dimensions for Selecting Packing Materials

When selecting packing materials, what dimensions should be considered?

1. Type of Equipment and Motion Mode

Determine what type of equipment the packing material is being used for and its motion type. For example, valve stem packing and pump shaft packing differ in their motion characteristics.

2. Physical and Chemical Properties of the Medium

Consider whether the sealed medium is a gas or liquid, its viscosity, corrosiveness, and permeability.

3. Working Temperature and Pressure

These are among the primary considerations when selecting packing materials.

4. Movement Speed

Packing seals typically experience some level of relative movement with the sealed surface, which is measured as linear speed.

5. Abrasive Particles

If the medium contains abrasive solid particles, this must be taken into account when selecting both the packing material and its structure. These factors are usually characterized by the degree of wear, heat generation, and the medium’s pH value, which indicates its corrosiveness.

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