Converting from Helium to Hydrogen

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Spencer Clegg

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Aug 8, 2022, 2:29:49 PMAug 8
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Helium is hard to find in our area and we are considering switching to hydrogen for our upcoming launch. Any tips on switching to hydrogen for our HAB launch? I am guessing our main concern is keeping it from exploding. But information about type of balloon (same as helium), calculations, filling precautions, etc. would also be appreciated. 

Spencer

John Laidler

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Aug 8, 2022, 2:43:36 PMAug 8
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The calculator you can find on the Random Engineering balloon page will give you figures for different balloons and gases. I would start there. 

I have seen a video of a hydrogen balloon which was deliberately ignited and it didn't explode. Just a sort of slow "whoompf" followed by bits of burning rubber falling down, which were the main hazard. You will only get an explosion if the gas is mixed with air before ignition. This shouldn't happen if the filling is done outside.

John

On Mon, 8 Aug 2022, 19:29 Spencer Clegg, <spence...@gmail.com> wrote:
Helium is hard to find in our area and we are considering switching to hydrogen for our upcoming launch. Any tips on switching to hydrogen for our HAB launch? I am guessing our main concern is keeping it from exploding. But information about type of balloon (same as helium), calculations, filling precautions, etc. would also be appreciated. 

Spencer

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Spencer Clegg

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Aug 8, 2022, 2:51:42 PMAug 8
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Very good information, thank you!

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Joe

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Aug 8, 2022, 3:04:25 PMAug 8
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EXACTLY!!!!! Finally someone posted what really happens! I have been using Hydrogen since our first flight in the 1980's next flight is flight #60

We would routinely while waiting for the chase and recovery team to come back after chasing the payload, we often would fill a large lawn type plastic trash bag with the Hydrogen and tie it off. then attach a say 20 foot long piece of small rope to it that has been soaked in diesel fuel.

we would hold the rope by it's end and light it, and let it go,
 the bag would get up a few hundred feet by the time the flame would get to it and all that would happen is a small orange hoomf and that's it.

Exploding requires pressures to be made.

Hydrogen under no pressure will NOT explode.

Just like gunpowder

OK light a fire cracker BOOM!

open a firecracker and make a pile of the stuff inside and now light that. wow excitement it burns with smoke and some sparks and a hiss sound but that's all.

Joe WB9SBD
KB9KHO Near Space Sciences

Spencer Clegg

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Aug 8, 2022, 3:12:08 PMAug 8
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Well that's comforting. Any other considerations? 

Mr P Clarke

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Aug 9, 2022, 4:00:52 AMAug 9
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Funny this should have popped onto Twitter at the same time I’m reading the hydrogen balloon conversation:


Spencer Clegg

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Aug 19, 2022, 10:18:08 AMAug 19
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Can someone point me to some safety protocols for filling a hydrogen weather balloon?

Just picked up the hydrogen tank yesterday. 

Ed Moore

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Aug 20, 2022, 7:25:59 AMAug 20
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Treat is with the same respect as any other pressurised gas, with obvious additions like avoiding sources of ignition. Fill outdoors, wear goggles or a face shield, some long-sleeved clothing might help you keep your arm hair if it were to flash off for some reason, but that's very unlikely. Check fittings and connectors for debris and foreign objects and do them up securely. If you're paranoid about leaks, a shot-glass' worth of 50/50 fairly liquid and water, dabbed onto joints with a paint brush, will detect leaks by bubbling up. Really, this latter bit shouldn't be necessary, but it's peace of mind if you'd like some.

Steve

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Aug 20, 2022, 7:40:39 AMAug 20
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Personally:

    * I would not be filling using H2 indoors - too many sources of ignition (light switches...) and dire consequences if ignited.

    * Ensure the balloon cannot rub against anything and generate static (e,g, canvas tent) - there have been incidents of balloon ignition.

    * Have Some form of visible "Highly Flamable" warning on the balloon if it comes partly filled (as they sometimes do) .

    * I can't see the need for flashback Arrestors (as suggested by ARHAB) - you have no plans to ignite the gas.

    Steve G8KHW

Spencer Clegg

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Aug 20, 2022, 1:09:43 PMAug 20
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I read somewhere to avoid a plastic nozzle to fill the balloon to avoid static caused by rushing hydrogen. Is this true? My filler hose has a plastic filler. 

Steve

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Aug 22, 2022, 6:35:09 AMAug 22
to Spencer Clegg, UKHAS

I remember reading about that several years ago - what I read wasn't very conclusive.   The hydrogen inside the tube and balloon becomes rapidly near 100% concentration (after mixing with any any trapped air) - so there would not be an ignition even if an internal discharge were to occur.  Maybe there is a chance as the balloon is detached from the fill tube.  Personally I haven't seen any indication of static in/on fill tubes or balloons, I haven't heard of any instances of ignition from this cause (where as I have been for a balloon rubbing on a canvas tent).

The domestic gas companions seem quite happy to pump flammable gas round in plastic pipes - although probably not at the velocities of a HAB fill.

    Steve

Spencer Clegg

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Aug 22, 2022, 9:41:15 AMAug 22
to Steve, UKHAS
Thanks! 
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