How does a pneumatic system with negative pressure work?

Since different types of exhaust systems are used, such systems are limited in distance and capacity. Under-pressure systems are frequently used in the transport of toxic and hazardous materials. These systems allow for dust-free supply and also provide an additional safety feature, as leaks in the pipe do not lead to contamination of the environment. With growing awareness about the need for pollution-free operations, under-pressure systems are gaining acceptance in a wide range of industries. Under-pressure systems range in size from small industrial cleaning operations to those for ship unloading, where capacities of several thousand tons per hour are common.