In China, fires caused by accidental ignition of polyurethane foam occur from time to time, which bring some negative effects to the application of polyurethane foam. 

Many experts abroad even believe that this problem is one of the keys to the continued development of rigid polyurethane foam in the future. 

Therefore, the flammability and safety of rigid polyurethane foam has become an important technical index of building materials. 

Building legislatures in many countries have formulated a series of non-flammable laws and regulations, at the same time, they have developed a series of testing methods for the combustion performance of polyurethane foam. 

The EU Polyurethane Standard has the following new provisions: 

The main results are as follows: 1. The classification of its material combustion performance grade is changed from the original five grades to A1, A2, B, C, D, E, F seven grades. 

2. The new EU standard is a series of standards, the second, third and fourth part is to determine the classification method through the fire resistance test, and the fifth part is about the external flame roof test to determine the classification method. 

3. The connotation of polyurethane on combustion characteristics has been extended from the original simple flame propagation and spread to include combustion heat release, combustion smoke density and combustion toxicity. 

At the same time, the new EU standard also provides that some test methods take into account not only the actual scenario, but also the end-use of the material. 

Therefore, the new EU standard is more practical representative and scientific, China's original 1997 version of the standard should also be changed and in line with international standards. 

Based on the above reasons, the Chinese government made a comprehensive revision of the original GB8624-1997 version of our country in 2006 with reference to the EU EN13501-1 standard, and formulated the new standard of GB8624-2006 "Classification method of Combustion performance of Building Materials". 

Except for the additional classification of smoke toxicity of materials in A2, B and C grades, the other parts are completely consistent with the EU standards. 

In 2012, according to the new changes in the situation of energy-saving buildings, the Ministry of Public Security formulated and promulgated the GB8624-2012 Standard "Classification of Combustion performance of Building Materials and products", which is now being implemented. 

The new national standard basically follows the GB8624-2006 version of the standard, but it has stricter specifications and testing standards. 

The grade standard of the original GB8624-2006 test is that the original GB8624-2006 test is grade A1 and A2 is non-combustible grade A, the original GB8624-2006 test is grade B and grade C is non-combustible grade B1. 

The original GB8624-2006 test was judged as grade D and grade E as combustible grade B2, and the original GB8624-2006 test as grade D and grade E as grade B3.