Patent ID: 8470062

Claim:
A drain tube for an air-oil separator system, the tube being configured substantially vertically in the system, the tube having an upper opening for receiving oil separated from air in the system on a collection-side of the system, and a lower opening for releasing oil separated from air in the system to a drainage-side of the system, wherein the upper opening has a horizontal cross-sectional area A 1 that is greater than a horizontal cross-sectional area of the lower opening A 2 , pressure in the drainage-side P 1 is greater than pressure in the collection-side P 2 , the tube has a height H 1 , the oil forms a film at the lower opening by surface tension and collects in the tube to a height H 2 prior to the film rupturing and the oil draining out of the lower opening, and P 3 is surface tension pressure associated with rupturing the oil film at the lower opening.