Hydrogen, we’ve all heard of it and none of us have ever seen it. That is, of course, because it’s a colorless and odorless gas. It is the lightest element known to man and the simplest in terms of its chemical structure. It’s the byproduct of many chemical reactions and is often used in industry, but is hydrogen a major fire hazard and if so, how should we treat it?
Hydrogen is very flammable. It is extremely reactive, especially when mixed with oxygen. In fact, this is why there’s so much water present on the Earth and such little pure hydrogen gas – it quickly reacts in the air to form water molecules.
This means that everyone should know a little bit more about hydrogen and fire.
Also read: What Makes Something Flammable?
Table of Contents
- What Is Hydrogen?
- Is Hydrogen Flammable?
- How Do You Put Out A Hydrogen Fire?
- Is Pure Hydrogen Toxic?
- Hydrogen As A Fuel: The Risks and Rewards
What Is Hydrogen?
Hydrogen is the first element in the Periodic table and the simplest.
Hydrogen atoms bond easily with themselves, and hydrogen is found as a gas, H2, which is two hydrogen atoms bonded together.
It has no color, no odor, and is not at all toxic and it’s the most abundant element in the universe!
75% of everything in the universe is made up of hydrogen.
For example, stars are mainly hydrogen though in a supercharged elemental state known as “plasma”.
On Earth, hydrogen is usually found in compounds.
Of these, water is the best known and most common of all, but it’s also present in almost all organic compounds and can be found in inorganic compounds too.
Hydrogen would have been the first element to be formed in the moments after the Big Bang that formed the universe.
Oddly, while the gas is considered to be non-metal, at very high pressures it can assume the properties of metallic elements.
What Is It Used For?
Hydrogen ions are an essential part of nearly all acid-base reactions as they allow for the easy transfer of protons between different molecules in solution.
Our understanding of hydrogen, because it’s the only neutral atom that they can apply the Schrodinger Equation to, has allowed for the development of quantum mechanics.
The two biggest uses for hydrogen industrially, where it is produced by breaking down natural gas, are for ammonia production and hydrocracking fossil fuels.
It’s also commonly used in metallurgy to “embrittle” (that is make them easy to crack) metals.
Is Hydrogen Flammable?
Hydrogen is highly flammable and burns at very low temperatures in the presence of a naked flame or spark.
It produces large amounts of heat when burning in oxygen releasing 286 Kilojoules for every mol of hydrogen that is burned.
The flame produced in this fire is nearly invisible as it sits mainly in the ultraviolet light spectrum and this is why when a hydrogen leak catches fire the person responsible for locating the leak may need a “flame detector”.
However, if the hydrogen fire is not a pure hydrogen-oxygen fire, the flame is more likely to be a blue tone similar to that of the natural gas burning on a stovetop.
When the Hindenburg Airship, an ill-fated balloon-style vessel filled with hydrogen gas, exploded the visible flames were not hydrogen flames but the flames of the material of the airship burning.
Also read: Is Methane Flammable?
Is It Explosive?
Hydrogen is not explosive in its pure form, however, in the air at concentrations between 4% hydrogen and 75%, it forms a highly explosive mix, and this can be triggered by heat, sparks, or even sunlight!
If chlorine is present, then hydrogen is explosive in the air in a mix of between 5% and 95%!
Thus, the storage of hydrogen is very important as a hydrogen leak can cause severe problems.
Is Hydrogen A Fire Risk?
Yes. As hydrogen is both highly flammable and potentially, also highly explosive, pure hydrogen must always be considered as a fire risk.
It must be stored carefully and all instructions on the material safety data sheet supplied with it must be followed.
If you are generating hydrogen as part of an industrial process at work, you must be trained in the storage and disposal of hydrogen as well as what to do if you suspect a leak has occurred.
Hydrogen catches fire as a gas or liquid at low temperatures which makes it flammable as opposed to combustible.
Can Hydrogen Spontaneously Combust?
This is a great question and one that a literature review from the UK’s Health & Safety Laboratory in 2008 tried to answer.
Sadly, for us, it wasn’t conclusive.
The reviewers felt that it was likely that hydrogen can spontaneously combust under certain conditions but could not demonstrate that this was the case using the existing literature.
Thus, they concluded that more research would be necessary.
From our perspective, we think that “probably” is a good enough answer to treat hydrogen as though it might spontaneously combust and take all proper precautions when storing it.
Can Liquid Hydrogen Explode?
Yes, the formal hazards associated with liquid hydrogen included both fire and explosions (and also asphyxiation potential and extremely low-temperature exposure).
This is probably not because liquid hydrogen will burn easily but because it’s very easy for hydrogen gas to form from liquid hydrogen and which is highly combustible and potentially explosive.
Once any gas began to burn, it would provide further heat to melt the liquid hydrogen, which would form more gas which would burn more, and so on, to create a sustainable chain reaction.
How Do You Put Out A Hydrogen Fire?
Extinguishing a hydrogen fire is not easy and the only sure way to stop a hydrogen fire is to remove the source of the hydrogen.
In general, fire professionals will allow a hydrogen fire to burn in a controlled fashion, if possible until it’s possible to remove the hydrogen source.
Secondary fires can be extinguished using water but water will not extinguish the main hydrogen fire.
Is Pure Hydrogen Toxic?
Hydrogen is not toxic and if you were to accidentally inhale some or consume some in “hydrogenated water” (a new health trend for some) then it would have no impact on your body at all.
In fact, as we’re made up mainly of water (which is hydrogen and oxygen), if hydrogen were harmful, it could be very problematic.
However, that doesn’t mean that you can breathe hydrogen and if you found yourself in a room full of pure hydrogen gas which had pushed out the oxygen – you could and would suffocate. (Assuming it didn’t catch fire, first).
Is Liquid Hydrogen Safe To Drink?
No. Liquid hydrogen should not be confused with hydrogen water.
Hydrogen water is water with a bit of hydrogen mixed in. We can’t see any benefit to drinking this but if you want to, go right ahead, it won’t harm you.
Liquid hydrogen, on the other hand, is frozen hydrogen and if you were foolish enough to attempt to drink it – it would freeze your lips, mouth, and any other part of your body it came into contact with.
This would kill you. So, don’t try drinking liquid hydrogen, please
Hydrogen As A Fuel: The Risks and Rewards
Given that hydrogen burns very easily and it burns cleanly, and it’s not hugely expensive to produce, it makes for an excellent fuel.
However, it’s worth noting that this does not mean that hydrogen is likely to become a popular fuel any time soon.
This is, of course, because it burns well and is an explosion hazard.
Do Hydrogen Cars Explode?
No. Hydrogen cells in cars are designed not to explode and while they can catch fire, so can petrol or diesel cars as hydrocarbons burn pretty well too.
Why Is It Not Commonly Used A Fuel?
For now, hydrogen is not commonly used as a fuel because it’s hard to store, hard to transport, and very difficult to handle.
The risks of using it simply outweigh the rewards, this may change in the future, but for as long as we’ve been alive, they’ve been extolling the benefits of hydrogen-powered cars and while the technology for these cars has been fully developed, they’re not in mass production anywhere, just yet.
How Much Does A Gallon Of Hydrogen Fuel Cost?
Hydrogen fuel costs about $0.0015 per gallon. That is assuming that you get it straight from a refinery and that your government doesn’t decide to add a large amount of taxation on top.
Yes, hydrogen is super cheap and if it ever could be transported and stored cheaply and safely, it would make for an excellent alternative to gasoline.