Doc 27212_01
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Technical Tip
Clean Air Zero
Overview
Clean Air Zero is a user-initiated VLI feature which compliments absolute detection and safeguards against
nuisance alarms.
This is achieved by introducing clean air into the detection chamber and taking a reference reading of the
chamber background. This reading is then offset against the actual environmental background to maintain
consistent absolute smoke detection over time.
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.
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 shut down.
2. The Clean Air Zero aspirator inside the detection chamber is activated, which circulates clean air only
within the detection chamber.
3. After a waiting period, a smoke reading is taken with clean air only in the chamber, which forms 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 shut down and the main aspirator is re-activated.
5. An event indicating that the Clean Air Zero process has taken place is added to the event log.
Preparation
•
The Clean Air Zero function shall be activated during every routine maintenance site visit
o
Clean and Back-Flush the VESDA pipe network as required prior to activating ‘Clean Air
Zero’.
o
Ensure dust or other contaminants have not fallen into the VLI pipe inlets if pipes are removed
for Back-Flush.
o
Check all pipes are re-inserted correctly into the VLI pipe inlets.
o
Power the VLI and observe for any fault conditions.
o
Re-normalise VLI
o
Activate Clean Air Zero function.
AUTHORISED DISTRIBUTOR OF VESDA
www.flamestop.com.au | sales@flamestop.com.au
