In the pipeline industry, to the product pressure requirements is very strict, usually under pressure: refers to gas pressure high gas state. For example, bike or car tyres, pump or play out from the end of the pump is positive pressure. Usually in industry, especially tiny pump (such as tiny, tiny air pump, the miniature mudline booster pump suction pump, play miniature gas circulation pump, the miniature play pump, filling etc) miniature air pump selection to want to involve in the concept. And the negative pressure? Is romantic of the absolute pressure (pressure) is less than the well with the elevation of the hair or atmosphere pressure (pressure), the relative pressure (pressure) negative, says negative pressure. The use of negative pressure is very common, people often make some space appear negative state, can use the ubiquity of atmospheric pressure for we play. For example, people breathing, when lung in extended state when the negative pressure in the lungs, internal and external form the pressure difference fresh air is forced into the lungs. Usually in industry, especially tiny pump (such as mini vacuum pump, the miniature air pump, the miniature gas pump sampling, the micro gas circulation pump, the miniature pumping air pump) in selection to want to involve the concept. For example, there is a mini vacuum pump, it can be in the form of 0.04 MPA air extraction of negative pressure, meaning can within the airtight container gas siphoned off 40%, and the remaining 60%, and outside atmospheres of pressure difference for 100 * (1-0.6) = 40 KPA (i.e. it the negative pressure value is:-40 KPA), in the common vacuum shown on the table for 0.04 MPA. (assuming the local atmospheric pressure is 0.1 Mpa usually customers on the rubber products have negative pressure requirements, simple said, "negative pressure" is lower than normal pressure (i.e., often said an atmosphere) of gas pressure to state. Also is we often say "vacuum".

(1) lower than the existing air pressure (for reference zero) pressure

(2) below the atmospheric pressure thin degrees. I company quality supervision department in order to strictly control the quality of the product, meet customer in the work stress requirements, professional equipment for each single products detection and sampling, ensure each machine products of excellent quality.