The flammability of fabrics is usually evaluated using the following methods:

1. U.S. Standard NFPA 701: NFPA 701 is the standard for flame retardancy of fabrics developed by the National Fire Protection Association (NFPA). The test method is designed to evaluate the burning characteristics of draperies and similar upholstery fabrics when exposed to open flame. The test determines the flame retardancy of fabrics by measuring the rate, duration and spread of flame when exposed to flames.

2. European Standard EN 13773: EN 13773 is the European standard for the assessment of flame retardancy of fabrics. This standard applies to fabrics used for upholstery, such as curtains, coverings, fabric wall coverings, etc. The test is conducted by exposing fabrics to standardized conditions. The test evaluates the burning characteristics, flame propagation properties and smoke development by exposing fabric samples to an open flame under standardized conditions.

3. ISO 6940 and ISO 6941: ISO 6940 and ISO 6941 are international standards for evaluating the burning behavior of fabrics. ISO 6940 is used to evaluate the burning performance of fabrics in a vertical state, while ISO 6941 is used to evaluate the burning performance of fabrics in a horizontal state. These standards measure parameters such as burning rate, burning time, and ash formation.

These standards and test methods are designed to assess the flame retardancy of fabric materials and to ensure their suitability under fire conditions. Before testing, it is important to know the applicable standards and to categorize and evaluate the fabrics based on the test results. Specialized testing laboratories can perform these tests and provide certification or evaluation reports based on the results.