Pressure relief device and glass fiber weighing system

The pressure relief device comprises a material storage barrel, a limiting plate is arranged in the material storage barrel, the peripheral wall of the limiting plate makes contact with the inner wall of the material storage barrel, and a spring is fixedly arranged on the bottom side of the limiting plate. When the improved glass fiber weighing system is used, raw materials pushed into the material storage barrel by the coarse spiral material supplementing device and the fine spiral material supplementing device directly slide to the limiting plate, and due to the fact that the pressure of the limiting plate on the spring is increased, the spring shrinks, the limiting plate moves downwards at the same time, and a space is reserved for the raw materials pushed in subsequently. And meanwhile, the compressed spring applies a counter-acting force to the weighing mechanism, so that the raw materials on the top side of the limiting plate are weighed, finally, when the raw materials move to the limiting plate, the l