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13641Re: [GPSL] Hydrogen usage

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  • Zack Clobes
    Oct 25, 2013
      My regulator is a single stage, and I don't remember the outlet pressure off hand, but you want as high as you can get, or else you could be there all day filling.  Our balloons fill in about 10 minutes, maybe less.

      As for the static build-up, I have a bit of an issue with that.  For us, we purge our fill line and our balloon of "air" before filling the H2.  So even if there was a spark in the fill line, there is still no oxygen to support combustion.  I've proven that in controlled tests, and it appears that it takes about a 50/50 ratio (+/- 20-30%) of oxidizer and H2.

      To further support this, I (and probably most others) vent our bottles before returning them to the supplier, and I never use a regulator at that point.  I would submit that this is far more dangerous than filling a balloon.

      • Remember that the 2000psi cylinder is your most dangerous component.
      • Fill outdoors.
      • Have an extinguisher handy (not for the H2, but for the latex that could catch fire and fall back to the ground).
      • Be aware.

      Zack Clobes, W0ZC
      Project: Traveler

      On Fri, Oct 25, 2013 at 9:42 AM, Hanson, Douglas R CIV SPAWARSYSCEN-PACIFIC, 63800 <douglas.r.hanson@...> wrote:
      I would like some help determining the safest use of hydrogen. Hydrogen providers often caution me about static charge buildup if the flow rate into the balloon is too fast. What is considered a safe fill rate? How long should I take in filling a 1600g Hwoyee (assuming I'm only using about 210cu.ft. of gas)? There are many CGA 350 regulators available, but does the outlet pressure of the regulator matter? Single stage or two stage? I look forward to the great feedback. Thank you.

      Ryan, KJ6YXG
      San Diego Near Space Project

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