Richard and Robert, When testing a power supply for NRTL/European Test Hpuse some years ago, during one of the component abnormal tests, an electrolytic capacitor vented and emitted gases/fumes/electrolyte as you describe. Since there was no fire hazard and power supply complied with the electric strength test after the fault, the only item left was to prove that the emitted gas/electrolyte was non-toxic. For this, we obtained a declaration from the capacitor manufacturer and the power supply was then Recognized/Approved.
Best Regards, > > I came upon such an incident at Digital Equipment when I worked there. As I > recall the product was a UPS, and don't believe it was a Digital product. > Someone else did the followup investigation, so I don't know much about it. A > capacitor bank of appreciable size, about 1 x 1 x 1.5 ft as I recall of about > a > dozen caps vented (or at least some of them did). There was an array of holes > directly above from which flames escaped about one to two feet above the > cabinet. Someone tried to extinguish them with a dry chemical extinguisher, to > no avail, but the fire self extinguished soon after. > As I understand it, the vented gases from the electrolytic caps are hydrogen. > There appeared to be almost no fire damage. Even the cabinet paint was in good > shape. No flame marks or soot on the ceiling. Most of the damage was in > cleaning up the dry chemical which ended up in every corner of every machine > in > the computer room. > Obviously this would be a failure to meet safety standards. I don't know what > failure triggered the failure, but you can see there are some significant > risks > to banks of large electrolytics which may not be easy to solve with simple > enclosures. > > Bob Johnson > > "WOODS, RICHARD" wrote: > > > It has come to my attention that an internal short in some types of > > construction of electrolytic capacitors can cause flammable gases to vent > > under high pressure. In some failure modes, a spark internal to the > > capacitor, can ignite the flammable gases prior to venting creating a > > virtual blow torch. Thus it is possible that a capacitor failure can create > > a fire internal to an enclosure, and it is possible that the ignited gases > > could actually escape a properly designed fire enclosure. > > > > Have you encountered this type of capacitor failure? Did the flammable gas > > cause ignitions internal or external to the fire enclosure? Do you know of > > additional sources of information on this subject? > > > > --------- > > This message is coming from the emc-pstc discussion list. > > To cancel your subscription, send mail to [email protected] > > with the single line: "unsubscribe emc-pstc" (without the > > quotes). For help, send mail to [email protected], > > [email protected], [email protected], or > > [email protected] (the list administrators). > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > > PETER S. MERGUERIAN MANAGING DIRECTOR PRODUCT TESTING DIVISION I.T.L. (PRODUCT TESTING) LTD. HACHAROSHET 26, P.O.B. 211 OR YEHUDA 60251, ISRAEL TEL: 972-3-5339022 FAX: 972-3-5339019 E-MAIL: [email protected] Visit our Website: http://www.itl.co.il --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
