Quote of the day—John D. Clark

There is a delightful extra something about a hydrogen fire — the flame is almost invisible, and at least in daylight, you can easily walk right into one without seeing it.

John D. Clark
1972
I G N I T I O N !: An Informal History of Liquid Rocket Propellants
[This is good to know if you buy your liquid hydrogen by the rail car.—Joe]

11 thoughts on “Quote of the day—John D. Clark

  1. This lends weight to the theory that the Hindenburg’s impressive flames were from the coating on the fabric. Mythbusters did a demo saying the coating was basically rocket fuel.

    • A researcher discovered that there was still pieces of that fabric in/on the ground where the Hindenburg died. And they were still highly flammable!
      Further research at the builder’s archives turned up documents showing that they figured out what actually occurred, about a month later. The company never released the info, since it made them look bad. Better to let the world frown at the US for not supplying Helium, forcing them to use that terrible hydrogen.

  2. Having worked extensively in a lab doing work with metal hydrides for hydrogen storage I can attest to the fact that it burns almost perfectly cleanly and with almost no visible flame. The only leak I ever had self-ignited (through self-generated static electricity) and I only noticed it when one of the stainless steel fittings started to melt.

    • Oh yes. It’s not quite up to acetylene standards, but close. One standard application for hydrogen torches is in lab glassware work, at least traditionally. My favorite classic textbook “Procedures in experimental physics” by John Strong describes it nicely.
      In fact, you can get a flame hot enough to vaporize tungsten — see page 37 in “Ignition”. When a rocket scientist describes that as “living dangerously” you really want to pay attention…

      • Wow! I had no idea. Google says over 6,000 F to melt tungsten. I is impressed. I guess I always assumed hydrogen burned cool what with being so low on the periodic table. I wonder what other assumptions of mine are very wrong? Please don’t answer that 🙂

        • I guess I slightly overstated things; the experiment reported in Ignition isn’t quite up to the boiling point of tungsten (though it’s way over the melting point).
          As for periodic table, as a general rule the strongly reducing elements are on the far left (how appropriate), and more so the further down, while the strongly oxidizing elements are on the far right and more so near the top. When dealing with compounds, things get more complicated, partly because some compounds have negative heat of formation (they produce energy when taken apart) — acetylene is a well known example, CF3 a more obscure one.
          Read the book, Robert, it will boggle your mind where chemistry is concerned.

          • Whenever I start to think I’m smart, I remind myself I don’t have the right kind of brain to be a chemist… 🙂 I thoroughly enjoyed high school chemistry wherein I was told if we ever find the remains of a sufficiently-advanced extraterrestrial civilization, that the Rosetta Stone will be their periodic table; that thought has always pleased me.

  3. Is this the book that refers to an explosion as a “hard start?”

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