Sorry, this family of products is no longer available. For recommended replacements see mass-flow-controllers.
The 1640 Pressure-based Mass Flow Controller is a metal-sealed instrument with standard 3-inch footprint, designed to meter and control gas flows in low-line pressure applications, such as Ion Implant, where thermal mass flow controllers are limited in their ability to accurately measure flow. The 1640 utilizes the principle of sonic flow through an orifice, a condition met when the upstream control pressure is at least twice the downstream pressure. Under these conditions, mass flow is proportional to the control pressure.