The AFP-3 type is a pneumatic clamp valve specially designed for train vacuum toilets according to the unified design standards of Chinese trains. It is an upgrade of the AFP-1 and AFP-2 series products based on years of technical experience in the application of CRRC systems. This series of products is also gaining increasing applications in other industrial fields. The main performance of its upgrade includes that the valve body structure is more in line with the processability of plastic processing, thereby improving the reliability of the mechanical strength of the plastic valve body. It is replaced with high-strength plastic, and a stainless steel end cover is added to cover the plastic structure to further ensure the resistance of the valve body and inserts to external forces. The temperature resistance range of the inner sleeve is wider, the inner sleeve life is longer, and the overall valve life is several times longer.