[EvanAnderson]

Fun story re: the term "explosion-proof":

I was given a tour of an industrial facility where conditions required explosion-proof equipment. The tour guide made a point of calling out the explosion-proof motors in one of the rooms.

One of the other tour group members asked the question "Why would it matter if these motors survived an explosion?"

I visualized the facility exploding in a fiery blaze and a motor, fully intact, tracing a high parabola into the sky and landing, unscathed, in the front yard of a house.

The tour guide had to awkwardly answer: "Explosion-proof means that it won't cause an explosion."

[AdamJacobMuller]

I don't think it's a silly question, my first thought about explosion proof would also be able to survive some level of explosion.

Especially for cameras in potentially hazardous or critical areas, being able to capture details of their final moments could be important (obviously great to have cameras which [also] don't cause explosions in the first place).

I can also think of many situations in which you would want motors which are rated to survive for some time through an explosion, for example something which is powering a fire sprinkler or ventilation system to give people time to escape. The military has "battle switches" on lots of equipment for this reason, better to remove safeties and destroy the equipment than have the equipment protect itself and stop working in a critical situation, potentially costing a soldier their life.

[EvanAnderson]

It's definitely not a silly question. I shared it because I really enjoyed the image that came to my mind when it happened.

It was a formative experience for me, too. I try really, really hard to explain terms-of-art to my audience if I'm unsure of their familiarity. "Reading the room" can be difficult sometimes so I try to always preface w/ "Stop me if you know this already...".

I also learned not to be afraid to speak up when terminology isn't familiar to me. I've no doubt that's made me look ill-informed in some situations. I'll always take the judgement of others re: my knowledge vs. acting on a bad assumption later.

There are consequences (sometimes significant ones) from assuming somebody knows what you're talking about. People who act like they understand something when they don't (either because they're afraid to ask, or because they don't know they don't understand) are dangerous.

[AdamJacobMuller]

> The tour guide had to awkwardly answer

That bit made me think otherwise.

> I also learned not to be afraid to speak up when terminology isn't familiar to me.

100% agreed. I don't care much if others think I'm stupid. I care about actually being educated and understanding the situation. If someone thinks me asking questions makes me stupid, I'm probably better off with them thinking that and avoiding me for it :)

[EvanAnderson]

> > The tour guide had to awkwardly answer

> That bit made me think otherwise.

I could have phrased that better. It was clearly awkward for the tour guide. I think the guide could have handled it in a less awkward way— maybe with some humor.

I found it amusing by way of the image it created in my mind, but that shouldn’t be taken as me discouraging others asking questions.

[dingaling]

> "Explosion-proof means that it won't cause an explosion."

Surely that should be "non-explosive".

Otherwise rain-proof and fire-proof could have interesting overloaded definitions...

[idbehold]

> Explosion-proof means that it won't cause an explosion

Wait, what? The implication is that their other cameras regularly cause explosions?

[mcpherrinm]

A regular light switch might spark as you flip it, or a power switch on electronics.

Some electronics use a spark gap as a form of surge protection:

https://en.wikipedia.org/wiki/Spark_gap#/media/File:PCB_Spar...

None of that would be acceptable in an environment that requires intrinsically safe equipment.

The electronics also need to be carefully current-limited so there's no chance they overheat and cause an explosion that way too.

[somerandomqaguy]

The term is Intrinsically Safe. It's for equipment that is guaranteed won't be an ignition source, specifically intended for things intended to be operating in confined areas where there's a danger that combustible gases can build up.

[hedgehog]

To reinforce, this is harder to achieve than it might seem. Sparking in switches and buttons and electrostatic discharge both are kind of invisible in normal environments but can be disaster on an oil rig or in an area of a hospital where pure oxygen is flowing. All the paperwork and monitoring to make sure that the design is correct and that the manufacturing stays within spec costs money too.

[woofcat]

It has been certified that it can/shouldn't produce any sparks or arcs in the event that it's in a gas filled room.

[c_o_n_v_e_x]

That's only for one form of explosion protection. Some methods of protection are for explosion prevention, other forms are mitigation.

Explosion proof / flame proof enclosures don't prevent explosions. Their sole purpose is to contain the explosion and to ensure that the gases escaping from the enclosure do not ignite the surrounding atmosphere. The beauty of a flameproof enclosure is that I can put standard, non-protected electronics into an enclosure and use them in a hazardous area. It's a much more affordable way of deploying electronics into hazardous areas, rather than designing from scratch and certifying.

[kevin_thibedeau]

Yes. There are non-sparking explosion proof hand tools that need to be used in such environments. Naturally, electronics are a hazard as well.

[c_o_n_v_e_x]

>Wait, what? The implication is that their other cameras regularly cause explosions?

Non-explosion protected electronics... sure. All you need is an atmosphere of sufficient concentration and a spark with sufficient ignition energy OR a hot surface that is above the atmosphere's auto ignition temperature (think a hot resistor on a PCB). Some chemicals have absurdly low auto ignition temperatures or ignition energies. Engineers must spec equipment for chemicals they expect to encounter within the hazardous area. Engineers also have to factor in how often the flammable atmosphere will be present. All of this is spelled in out IEC60079 for Europe and RoW. US has their own standards.

[palotasb]

Think about oil rigs or coal mines where all electronics are potential sources of sparks/arcs and thus explosions.

[c_o_n_v_e_x]

Coal mining equipment explosion protection is particularly onerous as you have to protect against dust (coal dust) and gas explosions (methane).

[kayfox]

> "Explosion-proof means that it won't cause an explosion."

Another industry term for this is Intrinsically Safe.

[Animats]

They're not the same. Intrinsically Safe means it has too little energy in it to cause ignition. Explosion-proof can be achieved either by intrinsic safety or an enclosure capable of containing the worst that can happen inside it.[1]

[1] https://blog.pruftechnik.com/intrinsically-safe-vs-explosion...

[Graffur]

TIL thanks

[silisili]

Interesting. I'd have made the same assumption. GPs link uses the term 'explosion protected', and is definitely talking about the former, being safe in an explosion.