Talk:Intrinsic safety

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Untitled[edit]

Merge with Intrinsically safe - I agree that the two articles should be merged; they are about the same subject. The main article should be Intrinsic safety as that is the name of the subject. "intrinsically safe" is an adjectival clause to describe equipment that is intrinsically safe. Canthusus 14:45, 30 May 2007 (UTC)[reply]

A general introductory article on IS can be found here: http://www.ronan.com/artofis.pdf ,however the writer of this article would need to be contacted before it could be listed. The engineering page IEE has articles as well on this subject: http://ieeexplore.ieee.org/search/freesearchresult.jsp?history=yes&queryText=%28intrinsic+safety%29. I would be happy to do some work on this page as I have had 10 years experiance as a testing officer for Intrinsic Safety Equipment. [K. Harris - non member: 2:23pm, 18September UTC] —Preceding unsigned comment added by 203.171.97.78 (talk) 04:37, 18 September 2007 (UTC)[reply]

The two articles, Intrinsic safety and Intrinsically safe should be merged, providing the useful information in both articles is saved. (A. Carty 19:50, 27 October 2007 (UTC))[reply]

Agreed, as they seem to be two articles about the same thing. --75.165.120.11 (talk) 22:50, 31 December 2007 (UTC)[reply]

Johnatweston (talk) 14:37, 4 January 2008 (UTC) I agree that these 2 sections should be merged as they cover the same ground. The section should be titled "intrinsic safety" to match the title of the British Standard, IEC 60079-11, that covers the subject.[reply]

Agreed Roregan (talk) 21:51, 8 January 2008 (UTC)[reply]

Radio?[edit]

How can a radio be intrinsically safe? It's designed to produce several watts of RF energy and so must have a powerful battery inside. Does the US Coast Guard perhaps require a "non-incendive" or so-called "explosionproof" radio, not "intrinsically safe" ? --Wtshymanski (talk) 05:07, 21 August 2011 (UTC)[reply]

This is confusing: "Standards for intrinsic safety dictate that the equipment is fault-tolerant; the design must be shown to maintain approved levels of voltage and current with specified damage to limiting components, such as a shorted resistor."
Which equipment? The equipment inside the barrier or the safety barrier? As far as I know, resistors never short. I believe VDE is the only agency that requires fault tolerance of listed equipment.

Some radios can produce several watts, per Part 15 of the FCC regulations unlicensed radios are limited to 100 milliwatts. There are different classes of intrinsically safe depending on the atmosphere involved. Some classes I believe allow up to several watts. The batteries must be below a certain energy delivery level, and no capacitor can be large enough to store sufficient energy. -- :- ) Don 15:43, 26 September 2012 (UTC)[reply]

Yes, that's ugly and I'll try to fix it. Verifying the fault tolerance requires me to go downstairs and touch icky paper books of standards, but I'll put on my gloves and see what I can find.

Apparently radios can be intrinsicially safe, even with (relatively) high power battery packs inside; I'd love to read more about how they approve radios for IS. Lots of unlicensed radio services exceed 100 mW, which was the threshold back in the days of the 27 MHZ walkie talkie running on 9 volt "transistor" batteries; modern emission limits are often given in terms of V/m. --Wtshymanski (talk) 16:03, 26 September 2012 (UTC)[reply]

Standards for intrinsic safety dictate that the equipment is fault-tolerant; the design must be shown to maintain approved levels of voltage and current with specified damage to limiting components, such as a shorted resistor.

A hand-held or mobile radio's rated output wattage is not normally a potential source for ignition of environmental gasses or to break the symmetry of nervous crystal products, however you are correct in that it is possible that a radio transmission is capable of inducing electric currents in wires and on surfaces of objects enough that unintended ambient electrical currents can cause a problem.

But such transmitters as can cause significant induced currents enough to be considered a potential hazard are rare, present only in commercial radio transmitters and on board sailing vessels and other platforms where you might encounter 50K Watts of transmitted power from a single source. Such radios are not considered intrinsically safe due to their wattage, but the 2.5, 5, 45 watts encountered in hand-held and mobile transmitters induce such low currents in wires and equipment at distance and up-close that it's negligible.

There used to be prohibitions against utilizing hand-held and mobile transmitters when work crews used explosives. If you're as old as I am you may recall seeing road work crews posting requests for people to avoid using their 11 meter radios as they drive through construction areas where explosives are staged.

But that was really unnecessary precautions. There was a time when un-buffered nitro was used and when old containers transporting nitro was used where dried crystals could form, crystals that might possibly be shattered with a sufficiently string radio-induced current, but those days are long past.

An IS-compliant radio is engineered and certified to undeniably prove (within the range that anything can be proven or not) that it will not cause a fire, explosion, or any environmental hazard (other than the known non-ionizing radiation hazards of electromagnetic waves) even when the radio is damaged, leave alone operating as designed. SoftwareThing (talk) 22:17, 5 September 2018 (UTC)[reply]

Illustrations needed[edit]

Does anyone have any photos of IS hardware? Nothing shows up on Commons in a quick search. A diagram would help, too. --Wtshymanski (talk) 16:09, 26 September 2012 (UTC)[reply]

I had a spare safety barrier laying around, but I sold it. Those puppies are expensive. Actually, I'm trying to locate my book for an official schematic. -- :- ) Don 16:14, 26 September 2012 (UTC)[reply]

So close. Wish I had better pictures from my steelmaking days; but back then a "digital" camera meant you could work it with a finger. --Wtshymanski (talk) 16:24, 26 September 2012 (UTC)[reply]

ex-hazardous[edit]

The article uses the term "ex-hazardous", is it supposed to mean; explosive-hazardous, or ex(formerly having been)-hazardous. Best Regards. 212.140.251.35 (talk) 14:36, 8 April 2014 (UTC)[reply]

Yes, the text was extracted from another article where the "Ex N" classifications were originally described, so the text kind of assumes that a reader understands the "Ex" classifications. That needs to be fixed. SoftwareThing (talk) 22:00, 5 September 2018 (UTC)[reply]

IS Radios and Explosives[edit]

I know that the discussion is ancient however you might look here for photographs showing people working with Tovex explosives while wearing IS radios. While the 75-pound bundles were hoisted on people's backs, their radios were literally pressed up against the firebreak explosives. 22:23, 5 September 2018 (UTC) — Preceding unsigned comment added by SoftwareThing (talk • contribs)