Xtralis VESDA E-Series, Manual

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VESDA by Xtralis VESDA Pipe Network Design Guide
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the dilution of the smoke sample, leading to a lower reading after a longer time than would otherwise be the
case.
Figure 4-25: Smoke dilution effect over several air sampling points
4.9 Cumulative Sampling
Where HVAC systems distribute air within a protected area, any smoke will be dispersed and diluted.
Traditional point detectors will wait until one detector reaches 100% of the smoke threshold before alarming.
VESDA systems are able to
aggregate the detected smoke from all of the sample points and can provide
much earlier warning. As an example, If you have a room with four sampling points and each detects 25% of
the allowable smoke level the VESDA systems can aggregate the levels and alarm.
Cumulative sampling is a significant advantage in high air flow areas.