①. Gravimetric feeders have very high requirements for measurement accuracy, so the device composition of the equipment is designed for high precision. For example, during the entire operation process, the system is sealed, on the one hand, to ensure high precision, and on the other hand, to prevent the material from polluting the environment, these measures are all related to the material. The gravimetric feeder is suitable for powdery or granular materials and liquid materials. Such materials have some features like easy to scatter, easy to stick, easy to adsorb, easy to volatilize, etc. Therefore, more attention should be paid to the process to meet different requirements.