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Comment by GJim | Hacker News Reader

Petrol is also insanely dangerous, yet we seem to manage.

Petro is practically safe compared to ammonia. Petro only explodes in specific air-fuel situations. The vapors are harmful, but not deadly in small quantities like ammonia is. Calling petro "insanely dangerous" is wrong. Petro is the most dangerous substance normal people handle in quantity, but we allow normal people to handle it in quantity because it while it isn't safe it isn't all that dangerous.

Your standard household ammonia CONCENTRATE people sometimes use for cleaning is 99% water - you dilute it significantly for use. Even used correctly it is nasty stuff.

Petro (sic) only explodes in specific air-fuel situations

That seems to be true for ammonia as well, at least according to the Wikipedia page's [1] section on Combustion:

Ammonia does not burn readily or sustain combustion, except under narrow fuel-to-air mixtures of 15–28% ammonia by volume in air.

That doesn't sound too horrible, it feels like gasoline/petrol is easier to combust (although I know it's the fumes that are actually flammable).

[1]: https://en.wikipedia.org/wiki/Ammonia#Combustion

Maybe I wasn't clear. Ammonia is burning is not the worry. Ammonia in small quantities will kill you directly. no fire needed, it will kill you.

To be clear, "small quantities" are in units of parts per million. 5ppm (0.0005%) and the room smells of ammonia, 25ppm means you should be wearing a respirator, 500 ppm (0.05%) can be lethal.

Warning that 15% air-ammonia mixtures can burn is like warning that 100 kg of TNT could give you a concussion if it fell on your head. It's just not the concern at all.

This risk factor sounds less like a normal chemical substance and more on the level of uranium

It’s comparable to carbon monoxide, except you can’t smell that one.

Petrol (gasoline to Americans) is dangerous largely for is vapours. It's one of the lightest-possible liquid fuels with about 6 carbon atoms per molecule (C6).[1] Most ships don't burn petrol itself,[2] but rather heavier fractions of petroleum, generally either diesel (~C16) or bunker fuel (~30 or longer), which don't vapourise readily. It's possible to extinguish a lit match in diesel fuel (the vapours above petrol would ignite and/or explode), and bunker fuel generally won't even flow until it's been heated above the boiling point of water (spent steam from steamships is used to heat the incoming fuel both so that it will flow and to vapourise it before injection into boilers or diesel cylinders).

The comparatively small quantities of petrol carried in automobiles is not a grave hazard, though fuel tanks are protected against damage or ignition, and fires do happen. Larger vehicles, on land, sea, and air, often burn the comparatively safer kerosene (aviation) or diesel (heavy machinery).

________________________________

Notes:

1. "Distillate" and "NGL" (natural gas liquids) are used in some instances, and can boil well below 100°C. Butane boils at -0.5°C / 31.5°F.

2. As I'd just mentioned in an earlier comment. I thought a well-known cruise ship or ocean-liner had been converted to petrol, but can't find a reference. <https://news.ycombinator.com/item?id=43344605>

Like the sibling comment mentioned it is nothing compared to ammonia. Yeah if you dump it somewhere in the ocean it might decompose with less damage to the environment but I was talking about immediate damage to humans.

Ships don't run on petrol, they run on various grades of bunker oil which is basically just really thin lubricating oil.

You're thinking of something like regular fuel oil, like diesel or kerosene. Heavy fuel oil/bunker is very viscous, has to be heated to be pumped efficiently.

>You're thinking of something like regular fuel oil, like diesel or kerosene. Heavy fuel oil/bunker is very viscous, has to be heated to be pumped efficiently.

I assure you I am not.

I specifically compared it to lubricants to avoid a bunch of people mentally anchoring the discussion around diesel. Bunker C (the common one, also the most thick one) is basically on the automotive oil spectrum when it comes to viscosity.

Go to 0:00 for room temp and 9:00 for operating temp (which is low enough for a plastic soda bottle and a bare hand to be appropriate). https://www.youtube.com/watch?v=xZZ591x0Ajs. Sure looks like 5w20 to me. Def thinner than gear oils and any comparison to 000 grease or roofing tar on a hot day is laughable. Bunker fuel is solidly on the oil spectrum.

> very viscous > I assure you I’m not

> bunker fuel is solidity

You seems to be knowledgeable in that domain and has something interesting to share but I don’t understand your point. What is the scale 0.00-9.00 ? What is the preside point you don’t agree with GP? Please EMLI5.

> What is the scale 0.00-9.00 ?

Referring to the timestamps in the linked video (i.e. from the start of the video to 9 minutes).

My point is that it's misleading to people who don't have reason to deal in liquid fuels to characterize bunker oil as thick or viscous when it's only thick relative to fuels (which are generally pretty thin, they mostly pour like water) despite not being particularly viscous absolutely.

It's on the same order as most petroleum oils that people deal with and thinner than pretty much every petroleum product that is generally characterized as thick. Thinner grades of motor oil and most hydraulic oil is a bit thinner but thicker grades of motor oil, gear oils, all sorts of greases and tars are all more viscous. Bunker oil doesn't "need" to be heated to be pumped any more than motor oil does though heating it and the accompanying thinning does a lot to help with combustion which is why they do it (and then the rest of the systems that handle it get designed to take advantage of this) and invoking the fact that this is done kind of implies a comparison with the other petroleum products that get heated before being used and in most people's experience this is going to be products used to patch roofs and roads which is unhelpful because those don't even flow except at the highest extreme of naturally occurring temperatures. The only context in which bunker oil is particularly thick is if you're a fuel supplier and spend all day dealing in much less viscous stuff.

I guess it's just pedantry at the end of the day.

And yes, the numbers were timestamp references.

I've seen bunker fuel in a ship, and its consistency was best described as "tar-like". Mind, n=1 and uses may vary, but bunker fuel can be exceedingly thick. All the more so on high-latitude routes with fuel tanks near the outer hull and cooled by ambient water temperatures near freezing.

Decidedly thicker than automotive oil, and probably thicker than axle grease or vaseline / petroleum jelly.

The ship in which that was used (triple-expansion steam engine, late 1800s design, built and used during WWII) directed spent steam around the incoming fuel flow directly prior to boiler injection, and that steam then wrapped around the fuel line and part of the fuel tank itself to heat the oil to the point it would flow.

Side note: Venezuelan oil is very thick and viscous, and requires mixing with lighter fractions of petroleum to be pumped out of wells. Venezuela typically imports what would otherwise be waste light fractions of petroleum, generally from the US or Nigeria (heavily dependent on political winds) in order to do this. A significant fraction of US petroleum exports go to this or similar uses. (I suspect Canadian tar sands see similar treatment though I don't have a source on this.)

The differences in opinion here may be because we're comparing #6 in a cold ambient environment to #5/#6 in a warm ambient environment. Still, #6 is no grease.

https://en.wikipedia.org/wiki/Fuel_oil#Maritime_fuel_classif...

My god you are thick.

The point was that risks can be managed.

And you are being rather rude.

You can make the same point without resorting to name calling

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