18-07-2011, 21:40
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#37
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Full Member
Join Date: Sep 2008
Location: up to my elbows in muck
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Re: Smoke Alarm ?
Quote:
Originally Posted by katex
Thanks for all the feedback. No, wasn't fitted by the fire service ... but may do that next time ...
Realised battery could not be changed after trying to open it to stop it ... won't opern ... 1.30 a.m. and not funny.
Anyhow, seems OK just now, not happened since. Just that it was an unusually hot night .. 28 degrees downstairs and was hotter upstairs.
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Retlaw already answered this for you it is a SMOKE alarm, not a HEAT detector, heat will have no effect on a smoke alarm, how do you think this could possibly be in hot countries all the smoke alarms would constantly be going off. See below for an explanation on HEAT detectors
Fixed temperature heat detectors
This is the most common type of heat detector. Fixed temperature detectors operate when the heat sensitive eutectic alloy reaches the eutectic point changing state from a solid to a liquid. Thermal lag delays the accumulation of heat at the sensitive element so that a fixed-temperature device will reach its operating temperature sometime after the surrounding air temperature exceeds that temperature. The most common fixed temperature point for electrically connected heat detectors is 136.4°F (58°C). Technological developments have enabled the perfection of detectors that activate at a temperature of 117°F (47°C), increasing the available reaction time and margin of safety. This type of technology has been available for decades without the use of batteries or electricity as shown in the picture.
Rate-of-rise heat detectors
Rate-of-Rise (ROR) heat detectors operate on a rapid rise in element temperature of 12° to 15°F (6.7° to 8.3°C) increase per minute, irrespective of the starting temperature. This type of heat detector can operate at a lower temperature fire condition than would be possible if the threshold were fixed. Rate of rise detectors may not respond to low energy release rates of slowly developing fires. To detect slowly developing fires combination detectors add a fixed temperature element that will ultimately respond when the fixed temperature element reaches the design threshold.
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