Vacuum Isolation Valve

Vacuum isolation valves, throttle valves, automatic pressure-control valves, and chamber pressure controllers together manage exactly how much the chamber is connected to the pump and exhaust system at any given moment — isolation valves fully open or close that connection, while throttle valves and pressure controllers finely adjust it to hold a precise chamber pressure.

The throttle valve's continuous position adjustment is what actually lets a chamber hold a steady pressure even while gas is flowing in and being pumped out simultaneously. Chamber pressure during a process step is really a balance between gas flowing in (from the process recipe) and gas being pumped out — if that balance shifts, pressure drifts; a throttle valve partially restricting the path to the pump gives the pressure controller a continuously adjustable lever to compensate, opening the throttle more to drop pressure or closing it slightly to raise it, holding the setpoint steady even as incoming gas flow changes through a recipe.

Isolation valves, by contrast, exist for the moments when partial control isn't the point at all — only a complete, verified disconnect will do, such as venting a chamber to atmosphere for maintenance or isolating it during an emergency shutdown. Unlike the throttle valve's continuously variable position, an isolation valve is built to be simply and reliably fully open or fully closed, with no intermediate state — exactly the right behavior when the question isn't "how much flow" but "is this chamber completely connected or completely disconnected," a binary distinction a throttle valve's continuous range isn't designed to guarantee.

Isolation valves, throttle valves, and pressure controllers together give a chamber both the binary safety disconnect it sometimes needs and the continuously adjustable fine control that holding a precise process pressure setpoint requires, and most chambers rely on both working together rather than either one alone.