How to Determine the Thermal Class of Insulation Material from the Product Code
Insulation material product codes in the electrical industry are structured based on a four-digit numbering system, where the third digit indicates the thermal class of the product.
The meaning of each digit in the product code, from left to right, is as follows:
First digit – Represents the main category:
1 – Varnishes, resins, and adhesives
2 – Impregnated fiber products
3 – Laminated products
4 – Plastics
5 – Mica products
6 – Films, adhesive tapes, and composite products
Second digit – Indicates the subclass of insulation material.
Third digit – Refers to the reference operating temperature:
1 – 105 °C, corresponding to Class E insulation
2 – 120 °C, corresponding to Class A insulation
3 – 130 °C, corresponding to Class B insulation
4 – 155 °C, corresponding to Class F insulation
5 – 180 °C, corresponding to Class H insulation
6 – Above 180 °C, corresponding to Class C insulation
Fourth digit – Represents the sequential product variant number.
Example: Product Code 6630
The first digit 6 indicates it belongs to films, adhesive tapes, and composite products.
The second digit 6 specifies it is a composite foil made from film and synthetic fiber paper.
The third digit 3 signifies that the insulation material has a thermal class of B.
What is the Difference Between Medium-Alkali and Alkali-Free Fiberglass Tape?
There is a common scenario in our business: We often receive calls asking, "Hello, do you carry fiberglass tape?" Our typical response is: "Yes, we do. Which type do you need—medium-alkali or alkali-free?" Yet customers are often unsure of the difference.
In common applications, fiberglass tape is generally divided into two types: alkali-free fiberglass tape and medium-alkali fiberglass tape. So what are the key differences between the two?
Heat Resistance: Medium-alkali tape has lower heat resistance compared to alkali-free tape. After exposure to flame, medium-alkali tape becomes brittle and leaves a white residue on the surface, whereas alkali-free tape retains its flexibility and shows no surface residue.
Texture: Alkali-free tape feels soft to the touch, while medium-alkali tape is noticeably stiffer.
Mechanical & Chemical Properties: Alkali-free tape of the same specification provides higher tensile strength. However, medium-alkali tape offers better acid resistance than its alkali-free counterpart.
Application Recommendations: For electrical equipment with low temperature rise, medium-alkali tape offers a cost-effective solution. In high-temperature applications, alkali-free tape must be used. In environments with strong acidic or alkaline conditions, medium-alkali fiberglass tape is the preferred choice.
Therefore, both types of fiberglass tape have distinct advantages and are suited for different conditions. Selection should be based on the specific operating environment and application requirements.
Can Solventless Insulating Varnish 1140 be Mixed with Solvent-Based Insulating Varnish 1040?
No, they cannot be mixed. The curing mechanisms and drying rates of these two varnishes differ significantly.
Insulating Varnish 1040 (solvent-based) cures through an oxidative polycondensation reaction that requires oxygen, while Insulating Varnish 1140 (solventless) cures via a self-polycondensation reaction without the need for oxygen.
Curing Process: Varnish 1040 requires two-stage drying—first at low temperature and then at high temperature—with a relatively long curing time. In contrast, Varnish 1140 cures rapidly and completely at 130°C.
If these two varnishes are mixed, issues such as delamination, peeling, and incomplete curing of the coating are likely to occur, compromising insulation performance and reliability.