زکریا 3 سال قبل
Atmospheric Pressure
Since Vacuum is a measurement of atmospheric pressure it is important to understand how the air pressure around us works. Due to Earth’s gravity, everything with mass is pulled towards the Earth’s surface at 9.81m/s2 including the air. This makes the air pressure on the surface of the Earth similar to the water pressure on the bottom of the ocean. The lower you are to sea level, the higher the pressure. Likewise the higher the altitude, the lower the pressure. Atmospheric pressure at sea level is 14.7 PSI or 1013.25 mbar. At the peak of Mount Everest it is 4.6 PSI or 317 mbar. A vacuum pump will perform the same no matter the altitude or surrounding air pressure as a percentage of vacuum. For example a vacuum pump creating 90% vacuum at sea level has pulled the pressure of 1013.25 mbar down to 101.325 mbar. At Mount Everest, 90% vacuum is 31.7 mbar. However as the atmospheric pressure drops the holding force of the vacuum drops as well. This is because the differential in pressure is a subtractive measurement where % of vacuum is a proportion. 90% vacuum at sea level has the force of 911.925 mbar holding down the surface of the vacuum where at Mount Everest there is only 285.3 mbar.