VESDA by Xtralis
VESDA VLI Product Guide
www.xtralis.com
7
2.2.1
Clean Air Zero
Clean Air Zero is a user-initiated feature which is primarily intended to safeguard against nuisance alarms.
This is achieved by introducing clean air into the detection chamber and taking a reference reading. This
reading is then offset against the actual environmental background to maintain consistent absolute smoke
detection.
The user can initiate the Clean Air Zero process using Xtralis VSC. It takes up to 60 seconds to complete,
during which time the detector is offline.
Clean Air Zero Process
When the user initiates the Clean Air Zero process from within the Xtralis VSC software, the following actions
occur:
1. The main aspirator is turned off.
2. The Clean Air Zero aspirator located inside the chamber assembly is turned on. This aspirator pumps
clean air into the Chamber and removes any contaminated air.
3. After a waiting period, a smoke reading is taken with clean air in the chamber. This reading is the new
clean air background value and is used as a reference point against the actual environmental background.
4. The Clean Air Zero aspirator is turned off and the main aspirator is turned back on.
5. An event indicating that the Clean Air Zero process has taken place is added to the event log.