What is the difference between a positive pressure pump and a negative pressure pump

The positive pressure pump is completely different from the negative pressure pump. For example, in the direction of gas flow, the negative pressure pump is when external air is sucked into the suction nozzle, and positive pressure is injected from the exhaust nozzle, such as the air pressure level.

In fact, "negative pressure pump" and "positive pressure pump" are mainly artificially distinguished from function and main purpose. "Negative pressure pump" is mainly used where vacuum (negative pressure) is required, such as: pumping, gas analysis, gas circulation, gas sampling, vacuum adsorption, indirect water absorption, etc.; "positive pressure pump" is mainly used for needs. The pump is used as the power for gas transmission, airtight container pressurization, inflation and inflation, indirect water pressure, etc. It is usually used in medicine, scientific research, environmental protection, instrumentation, control, etc.