Deep Vacuum with Staged Air Ejectors
...an alternative to steam jet ejectors...

Standard Fox air ejector represent an excellent solution to industrial needs for exhausting gasses or evacuating with significant vacuum, i.e. shutoff to 1 psia. Below that vacuum level;, most engineers assume that a steam ejector or LRVP is needed. Fox Valve has shown that two stage air- ejector systems are a viable solution for many applications. They can generate shutoff vacuum levels of 0.1 psia - deep vacuum that had previously been thought of as unobtainable with air-driven jets. The image below shows what is meant by 'staging' two air ejectors.

	A two stage air ejector system can pull down to 20 torr or about 0.1 psia. Minimum line size is 2". Mini-eductors cannot be staged.
	This photo shows a two-stage Fox air ejector system installed above a hypersonic wind tunnel at Princeton University. Each stage is a 24" ejector.
Air Jet Boosters for use with Liquid Ring Vacuum Pumps The liquid ring vacuum pump (LRVP) is used throughout industry to provide moderate vacuum levels for a variety of industrial tasks. The level of vacuum they can pull is limited by the temperature of the sealing liquid. With an atmospheric air-powered ejector, the user can bypass this limitation and achieve much deeper vacuum levels. LRVP's that previously could only pull down to 40 - 50 Torr of vacuum can now reach 5 - 10 Torr with no additional power requirement.