The ILP is a pneumatically-actuated poppet valve with a bypass valve combined into a single unit. The main valve is a normally closed bellows sealed valve. The bypass valve is a spring to close, o-ring sealed valve located within the main stage.

In the first stage, the bypass valve pumps down slowly from atmospheric pressure to a preset vacuum pressure. In the second stage, the main valve opens, allowing use of full pumping speed.

A formed 321 stainless steel bellows, not edge-welded, prevents outgassing, virtual leaks, and particle entrapment between bellows convolutions and extends the main valve’s cycle life. We have optimized the bellows stroke length to assure a longer cycle life while maintaining a high conductance.

The bypass stage conductance is adjustable by turning an adjustment screw. The adjustment screw has machined detents that lock the screw into place during cycling. There are 10 detents per full turn. See Figure for the bypass pumpdown curve.

Vacuum systems often require a slow initial evacuation of the roughing or loadlock area of the system. This process is called soft start or soft pumpdown. The soft start process reduces turbulent flow during initial system evacuation, diminishing product contamination and damage. Often a bypass line is used to soft start a system, which utilizes system space and can clog, requiring frequent cleaning and maintenance. The Integrated LoPro (ILP) Two-Stage valve has been designed to replace the bypass line. The ILP accommodates the space constraints found on vacuum applications like loadlock and transfer chambers specifically in semiconductor or optical processing for which a cleaner environment is necessary. A heater jacket is available for processes with condensable materials.