Predictive Sash Valve Control (Psvc™) - Sidewall Sensing - Critical Room Control CRC-FHM User Manual

Predictive Sash Valve Control (PSVC™) – Sidewall Sensing
Moving the sash from fully closed to fully open is the most likely time a fume hood can loose
containment. When opening a fume hood's sash, the hood needs to respond immediately to
increase its exhaust so that the face velocity is maintained. The challenge with conventional hood
controllers using sidewall sensors is that they rely on dated hotwire technology to measure
airflow, which is relatively slow to sense and react to changes in air velocity. These hood
controllers also use conventional PI loops to slowly react to the lack of face velocity.
CRC's fume hood controller and sidewall sensor does not use hotwire technology. Its sensor
calculates a change in air velocity within 1/5 of a second. Its PSMC algorithm can also detect when
a user is opening the sash and, before the user is able to raise the sash to stop position, it will
increase its exhaust rate to maintain proper face velocity. This technology allows CRC fume hood
controllers to control to set point in under 1 second (<800ms).
To configure PSVC™, simply follow these steps:
1. Enable "PSVC" on the Exhaust Input Setup screen.
2. Turn on commissioning info.
3. Open sash to stop position.
4. Wait until hood is maintaining correct face velocity.
5. Press the "Set Stop Position" button.
Fume Hood Monitor and Controller – User Guide
To configure PSVC™ - Open sash to stop
position, wait until hood is maintaining
correct face velocity, then press the "Set
Stop Position" button.
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