SRC Forum - Message Replies


Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

Back to message list Topics List About this forum
Original Message:

Posted by: Diane Gordon (info@reliability.com )
Organization:Reliability Center, Inc.
Date posted: Tue Aug 28 10:20:00 US/Eastern 2001
Subject: Fire Detector Systems Reliability
Message:
Does anyone have any information on reliability that concerns fire detector systems, testing methods and equipment? Any help would be appreciated.


Reply:

Subject: Fire Detector Systems Reliability
Reply Posted by: Gary Sunada (gsunada@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Wed Sep 5 13:45:17 US/Eastern 2001
Message:
Underwriters Laboratories have a series of documents on the reliability and safety of smoke detectors. UL-217, “Single and Multiple Station Smoke Detectors”, states that detector units shall be designed to have a maximum failure rate of 4.0 failures per million hours (calculated by a full part stress analysis prediction as described in Section 2.0 of MIL-HDBK 217) or 3.5 failures per million hours (calculated by a simplified parts count reliability prediction from MIL-HDBK 217), either one calculated in a Ground Fixed (GF) environment.
For other detection systems, the following are also published by UL: -- UL-268, “Standard for Smoke Detectors for Fire Protective Signaling Systems” (non-self-contained type for connection to a household or industrial system control unit) -- UL-539, “Standard for Single and Multiple Station Heat Detectors” (mechanically operated single and multiple station fire alarm devices) -- UL-521, “Standard for Heat Detectors for Fire Protective Signaling Systems” (heat detectors as part of a single station smoke detector assembly)
Additional information can be found at the UL website, http://www.ul.com and its supplementary page, http://ulstandardsinfonet.ul.com
Also, we have two data points: -- A RAC reliability assessment done on a smoke detector; failure rate was calculated at 0.3117 failures per million hours (R. Arno, “Reliability Assessment of the 6052B Smoke Detector”, Reliability Analysis Center, June 1983) -- A generic fire detector, with a failure rate of 0.4440 failures per million hours; this figure is based on a “physics of failure” model (D.R. Earles, M.F. Eddins, “Failure Rates – Reliability Physics (The Physics of Failure)”, 1962)


Back to message list Topics List About this forum
Reply to this message