[Space] Inert gasses

Mikolaj Habryn dichro at rcpt.to
Fri Jan 15 15:43:07 PST 2010


Yeah, I think you're right. Nitrogen would give a little buoyancy, but
the cost savings aren't that significant, so I think we should just
defer until the day, have a couple of spare balloons and enough helium
to scrub the first launch if we bollocks it up. In the extremely
unlikely event that we recover the payload successfully off the first
launch, we can just launch it again :)

m.

On Fri, Jan 15, 2010 at 3:21 PM, Shannon Lee <shannon at scatter.com> wrote:
> So, just to re-iterate:  the part of the fill that's hard is that the thing
> you're filling gets more and more buoyant as you fill it; it's not at all
> hard to fill a balloon with a heavier-than-air gas, beacuse it just sits
> there; but an 8-foot balloon full of helium is very awkward to handle.
>
> The balloons you guys got look a lot easier to deal with than the ones we
> were using, so you may not have the problems we did, but I don't think
> you're going to see an accurate "practice fill" with the co2, unless maybe
> you rig the balloon to a pully with 17# of bricks on the other end?
>
> It seems to me that if you want a real practice fill you have to spend the
> extra $50 or whatever and get helium.
>
> --S
>
> On Fri, Jan 15, 2010 at 3:04 PM, Christie Dudley <longobord at gmail.com>
> wrote:
>>
>> Great call there!  I went ahead and called Atlas and they not only had way
>> better prices, are open Saturday and rent the regulator, they had some
>> interesting things to say about which gas to use.
>>
>> Costs:  N2 $28.77, CO2 $23.90, rental $0.26/day, reg $40-$100 to buy,
>> $8/month to rent.
>>
>> They also deliver for a charge of $20.
>>
>> The guy also explained to me why we don't want to use CO2.  It apparently
>> changes volume considerably when it expands and contracts.  Also we'd have a
>> hard time making it not come out as snow and freezing up the regulator and
>> all sorts of other problems.  The guy there indicated that it'd definitely
>> be far more trouble than the $5 we'd save on it.
>>
>> He also explained to me that the balloon filler would be much slower using
>> nitrogen than helium.
>>
>> So I guess if we want to go this route (which sounds appealing) we'd not
>> need to decide "rent or buy" before tomorrow.
>>
>> Christie
>> _______
>> Getting to the bottom of the hill is convenient. The view from the top of
>> the hill is stunning. Where would you choose to live?
>>
>>
>> On Fri, Jan 15, 2010 at 2:17 PM, someone wrote:
>>>
>>> Atlas Welding in Berkeley will rent you a regulator along with your gas;
>>> I dunno if they have co2, I know they have helium.
>>>
>>> --S
>>>
>>> On Fri, Jan 15, 2010 at 1:45 PM, Christie Dudley <longobord at gmail.com>
>>> wrote:
>>>>
>>>> I talked to airgas and praxair.  They each like to have an account.
>>>> They also have different sized tanks for the nitrogen.
>>>>
>>>> Airgas was $41.03 for N2 and $43 for CO2.  Their tank rental was
>>>> $0.85/day.
>>>>
>>>> Praxair was $40 for N2 and $35 for CO2.  Their tank rental was
>>>> $0.12/day.
>>>>
>>>> We will also need to buy a regulator, as these guys don't rent them at
>>>> all.  I inquired about the low end regulators:
>>>> Airgas starts around $130-140
>>>> Praxair starts around $90.
>>>>
>>>> Both places said you needed to set up an account with them because tank
>>>> rental is done monthly.  Praxair was clearly the better deal so I asked them
>>>> about terms.  They said that if we absolutely needed to have the stuff today
>>>> then they could work it out with a $250 credit card deposit refundable when
>>>> the tanks are returned.  Tanks would have to be returned Monday morning.
>>>>
>>>> So...
>>>>
>>>> 1) Is it worth the $35-$40 to go for the fill test this weekend?
>>>> 2) We're ready to buy a regulator?  This would be what we would want to
>>>> use for the helium as well, but not flammable gases like propane, as it
>>>> won't be reverse threaded.
>>>>
>>>> Christie
>>>>
>>>> _______
>>>> Getting to the bottom of the hill is convenient. The view from the top
>>>> of the hill is stunning. Where would you choose to live?
>>>>
>>>> _______________________________________________
>>>> Space mailing list
>>>> Space at lists.noisebridge.net
>>>> https://www.noisebridge.net/mailman/listinfo/space
>>>>
>>>
>>>
>>>
>>> --
>>> Shannon Lee
>>> (503) 539-3700
>>>
>>> "Any sufficiently analyzed magic is indistinguishable from science."
>>
>
>
>
> --
> Shannon Lee
> (503) 539-3700
>
> "Any sufficiently analyzed magic is indistinguishable from science."
>
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