Rubber and plastic insulation materials are widely used in central air conditioning systems, equipment piping, chilled water systems, and industrial insulation due to their high flexibility, good insulation properties, and outstanding water vapor resistance. When selecting materials or reviewing budgets, engineers pay the most attention to the core technical parameters of rubber and plastics, including thermal conductivity, density, water repellency, water vapor permeability, flame retardancy rating, and closed-cell ratio. These parameters essentially determine the energy-saving level, safety level, and long-term stability of rubber and plastics.

I. Thermal Conductivity: The Core Parameter for Measuring the Insulation Capability of Rubber and Plastics

The typical thermal conductivity range of rubber and plastic materials is 0.030–0.040 W/(m·K), which is considered low thermal conductivity. This means that it can effectively block cold loss or heat conduction.

For refrigerant piping, products in the 0.030–0.034 range should be preferred;

For air ducts, materials in the 0.036–0.040 range are permissible.

The lower the thermal conductivity, the more significant the energy-saving effect, but the cost also increases accordingly.

II. Density Affects Flexibility and Mechanical Strength

Common densities of rubber and plastics range from 45–80 kg/m3.

Low density: High flexibility, easier to wrap complex structures.

Medium density: Suitable for duct wrapping.

High density: Superior mechanical strength, used for equipment insulation.

Products with excessively low density often have poor elasticity and are prone to collapse.

III. Water Vapor Permeability Determines Condensation Risk

One of the biggest advantages of rubber and plastics is their low water vapor permeability, with standard data generally at μ≥3000–5000.

Its effects include:

Reducing condensation in refrigerant pipes

Reducing performance degradation due to water absorption

Improving long-term energy-saving performance of the system

This parameter is crucial in high-humidity areas (such as southern regions).

IV. Hydrophobicity and Closed-Cell Ratio Affect Durability

Rubber and plastics are mainly closed-cell structures, with closed-cell ratios reaching ≥95%, and high-quality products can reach over 99%.

High closed-cell ratio brings:

More stable thermal conductivity

Better water absorption control

Lower probability of mold growth

Condensation in engineering projects is mostly due to insufficient closed-cell ratio or improper thickness selection.

V. Flame retardancy rating is related to building fire protection system requirements

Mainstream rubber and plastic products are divided into B1 (flame-retardant) and B2 (combustible).

For areas such as central air conditioning systems, clean rooms, and computer rooms, fire protection requirements mandate the use of B1-grade materials. Substandard flame retardancy ratings not only pose safety hazards but also fail inspection.

VI. Dimensional stability and environmental protection rating are equally important

Dimensional change rate ≤2% ensures no shrinkage or powdering during long-term use.

Environmental protection rating of E1 or better is suitable for indoor use.

The environmental friendliness of rubber and plastics is particularly important in school, hospital, and office building projects.

Summary

The technical parameters of rubber and plastics determine their engineering performance. Correctly understanding the parameters and selecting appropriate models based on the application scenario can significantly improve energy efficiency and system stability.