Air pump with relief device configured for dispensing trace amount of air

A relief device in an air pump configured for dispensing a trace amount of air from the air pump, comprising:

• a main body defining an interior space and a discharge passage fluidly communicating with each other, wherein the discharge passage extends from a first end adjacent to the interior space to a second end which fluidly communicates with the outside of the main body, wherein the discharge passage is selectively closed and opened to the outside of the main body by a valve device, wherein the valve device is movable in the discharge passage, wherein the valve device includes a first sealing portion and a second sealing portion selectively engaging with the discharge passage to prevent air discharged to the outside of the main body through the discharge passage, wherein the valve device is movable between a first position in which one of the first and the second sealing portions engages with the discharge passage and a second position in which the other of the first and the second sealing portion engages with the discharge passage, wherein the discharge passage has a first length measuring from the first end to the second end thereof, wherein the first length is smaller than a second length which measures a separation distance between the first and the second sealing portions, wherein the valve device includes a first retaining side adjacent to the first sealing portion and a second retaining side adjacent to the second sealing portions, wherein when the valve device is moved to the first position, the first retaining side abuts against the first end of the discharge passage, and wherein when the valve device is moved to the second position, the second retaining side abuts against the first end of the discharge passage.