Fan Speed Options for FFUs
When a clean, in-tool environment encounters varying conditions, the ideal amount of hyper-clean air being dumped into the space changes. And so a simple, “set-it and-forget-it” rheostat fan control is increasingly being left out in favor of a more capable fan control system. Our two systems for addressing a variable volume requirement are detailed below.
1. The “Dual Speed” allows for the FFU to deliver different amounts of air under two distinct tool conditions. With 2 ea. separate speed controls, the fans in the system are being controlled by either one or the other at any moment in time. When the tool is sealed up and operating, the first speed control sets the fan speed, then when the tool energizes an external low voltage relay on the FFU, the second speed control (set at a higher setting than the first) takes over and the fans ramp up to dump additional air into the space and reestablish the original differential pressure level under the new condition.. Easy, cost effective, functional.
2. For specifications that require the FFU to hold a given differential pressure in a clean space, our unique Dual/Mode APCS (automatic pressure control system) is the choice. With the Dual/Mode/APCS system you have manual control when the FFU is first installed and the system is not ready for APCS, and then when the tool is ready to be tested as a complete unit, the APCS is there, with the flip of a switch, to meet the specification.
Automatic Pressure Controlled (APC) FFUs (PDF Presentation)
In the above picture the Dual Mode/APCS selection is made via the manual switch, top/right. Optionally this switch can be replaced by a low voltage relay to allow mode selection directly from the tool. When in manual mode the speed control rotates near 360 degrees, offering complete fan control, and when the switch is flipped to APCS mode the speed control doubles as the pressure set point selector. Typically the far clockwise positions of the switch indicates a hold pressure of 0.015”, and the full counter clockwise position indicates a zero pressure condition, putting the commonly desired system pressure range of 0.005”-0.008” right in the middle of the dial. See PIC below.
Some other interesting features on this FFU include integral ionization outputs (both power and programming) for the latest generation Simco-Ion 5635 modulated pulse bars.
