Rotary vane pump oil that has taken up water and formed an emulsion, showing as a creamy or cloudy look in the sight glass. Water in the oil raises its vapour pressure, so the pump's ultimate pressure climbs, and the vanes and bearings start to corrode. The cure is a long run with gas ballast open, or a drain and refill if the emulsion will not clear.
Oil's milky in the sight glass on pump 3, ballast it overnight and check it again at handover.
Also heard as
- milky
- cloudy oil
Related terms
Gas ballast
Controlled bleed of air into an oil-sealed pump's compression stage that keeps vapours from condensing in the oil.
Rotary vane pump
Oil-sealed positive displacement pump in which sliding vanes sweep gas around an off-centre rotor.
Wet
Said of a chamber whose walls still hold adsorbed water, so it pumps down slowly and stalls high.
Vapor pressure
Pressure at which a liquid or solid is in balance with its own vapour, which decides what can go inside a chamber.