Helium in a tank?


Larry
 

My payload went up at a slower rate that I had forecasted last time and I know I just got kind of lazy and sloppy.  But even with me adding weight to the payload and not accounting for it the helium should have caused the milk jug to go neutrally buoyant with the amount of gas that I got from the burst calculator.  We ended up emptying the bottle into the balloon which should have been 19 cu ft more than required.  I am guessing the burst calculator was correct.  Is there any reason for me to doubt the amount of helium in the tank as long as I verify the pressure is correct?  Should I ask the welding supply shop about the purity of their helium?

I am trying to be more careful this time

Larry
KJ6PBS


Mark Conner N9XTN
 

I think helium from virtually any industrial gas supplier, even if labeled "balloon grade", is at least 99% purity, and often balloon grade is 99.99%.  Five nines is decent for most all industrial uses and six nines is towards laboratory grade.  You can ask if you got balloon grade or industrial grade, might even say on the invoice.  At Matheson (fka Linweld here), they put stickers on the balloon grade cylinders and the industrial grade ones aren't marked, but it's been several years since I got helium from them.

The small party balloon cylinders don't seem to have a fixed purity standard.  I read once that they sometimes blend with ~20% oxygen so that people who want to make Donald Duck voices with it don't end up asphyxiating themselves.  Don't bet your life on that though.

It's possible temperature effects might have affected your positive lift.  Other errors in the overall system probably are larger than the effect of having two vs five nines helium purity, unless you're doing flights where you measure lift in a few grams instead of a few pounds. 

73 de Mark N9XTN




On Sun, Jul 19, 2020 at 7:56 PM Larry <larry.phegley@...> wrote:
My payload went up at a slower rate that I had forecasted last time and I know I just got kind of lazy and sloppy.  But even with me adding weight to the payload and not accounting for it the helium should have caused the milk jug to go neutrally buoyant with the amount of gas that I got from the burst calculator.  We ended up emptying the bottle into the balloon which should have been 19 cu ft more than required.  I am guessing the burst calculator was correct.  Is there any reason for me to doubt the amount of helium in the tank as long as I verify the pressure is correct?  Should I ask the welding supply shop about the purity of their helium?

I am trying to be more careful this time

Larry
KJ6PBS


Steve G8KHW / AJ4XE
 

You can get a good estimate of the purity of a gas by calculating the lift per unit volume. The typical "balloon helium" we get here in the UK is about 95-97% pure (the remaining 3 - 5% assumed to be air).  The lift per unit volume of balloon helium here is quite close to 1.0Kg/cu m (a rather lucky alignment).  If I have done my math right that's also almost exactly 1.0oz per cu ft.

If you know the weight of the balloon, the measured neck lift, and how much gas should have been in the tank you can calculate the lift per unit volume.

    Steve

On 20/07/2020 01:56, Larry wrote:
My payload went up at a slower rate that I had forecasted last time and I know I just got kind of lazy and sloppy.  But even with me adding weight to the payload and not accounting for it the helium should have caused the milk jug to go neutrally buoyant with the amount of gas that I got from the burst calculator.  We ended up emptying the bottle into the balloon which should have been 19 cu ft more than required.  I am guessing the burst calculator was correct.  Is there any reason for me to doubt the amount of helium in the tank as long as I verify the pressure is correct?  Should I ask the welding supply shop about the purity of their helium?

I am trying to be more careful this time

Larry
KJ6PBS

Virus-free. www.avg.com


K. Mark Caviezel
 

Caution:
I have encountered at least two industrial gas suppliers that offer lower cost 'balloon grade helium' which is not 99% or better helium.(!)  It is 30%-40% nitrogen.  The thought and rationale is that for normal party balloons, the inclusion of lower cost nitrogen allows persons to fully inflate party balloons, they'll float just fine and a bit cheaper than going with pure helium.  And this will very seriously screw up lift and burst calculations if you use it in a high altitude balloon. I've never used it.  But both times it was offered to me it took a surprising amount of dialog with the industrial gas guys to suss out that it is a 60-40 or 70-30% mix of helium and nitrogen. I don't necessarily fault the guys working at the industrial gas suppliers, they've undoubtedly been briefed that their balloon grade helium is the best stuff for filling balloons.  For 99+% of their customers that are filling balloons it probably is.


steve potter
 

I ran into that with a tank from oxarc, entire s cyl and it didn't lift off the ground and by the calculations we did the s cyl should of been a couple of extra cubic feet. It was great that a fellow ham invited lived about a quarter mile away from the launch site and had a tank at his house. He's not even into balloons but apparently we are all a bit different than the rest of the world.


On Mon, Jul 20, 2020, 11:40 AM K. Mark Caviezel via groups.io <kmcaviezel=yahoo.com@groups.io> wrote:
Caution:
I have encountered at least two industrial gas suppliers that offer lower cost 'balloon grade helium' which is not 99% or better helium.(!)  It is 30%-40% nitrogen.  The thought and rationale is that for normal party balloons, the inclusion of lower cost nitrogen allows persons to fully inflate party balloons, they'll float just fine and a bit cheaper than going with pure helium.  And this will very seriously screw up lift and burst calculations if you use it in a high altitude balloon. I've never used it.  But both times it was offered to me it took a surprising amount of dialog with the industrial gas guys to suss out that it is a 60-40 or 70-30% mix of helium and nitrogen. I don't necessarily fault the guys working at the industrial gas suppliers, they've undoubtedly been briefed that their balloon grade helium is the best stuff for filling balloons.  For 99+% of their customers that are filling balloons it probably is.


Larry
 

I called and he assured me it was pure helium.  ???  I can't see another explanation why it didn't lift.  Anyway after checking the cost of gas and the cost of conversion ....  Hydrogen here we come

Larry


On Mon, Jul 20, 2020 at 8:39 PM steve potter <spotterotter@...> wrote:
I ran into that with a tank from oxarc, entire s cyl and it didn't lift off the ground and by the calculations we did the s cyl should of been a couple of extra cubic feet. It was great that a fellow ham invited lived about a quarter mile away from the launch site and had a tank at his house. He's not even into balloons but apparently we are all a bit different than the rest of the world.

On Mon, Jul 20, 2020, 11:40 AM K. Mark Caviezel via groups.io <kmcaviezel=yahoo.com@groups.io> wrote:
Caution:
I have encountered at least two industrial gas suppliers that offer lower cost 'balloon grade helium' which is not 99% or better helium.(!)  It is 30%-40% nitrogen.  The thought and rationale is that for normal party balloons, the inclusion of lower cost nitrogen allows persons to fully inflate party balloons, they'll float just fine and a bit cheaper than going with pure helium.  And this will very seriously screw up lift and burst calculations if you use it in a high altitude balloon. I've never used it.  But both times it was offered to me it took a surprising amount of dialog with the industrial gas guys to suss out that it is a 60-40 or 70-30% mix of helium and nitrogen. I don't necessarily fault the guys working at the industrial gas suppliers, they've undoubtedly been briefed that their balloon grade helium is the best stuff for filling balloons.  For 99+% of their customers that are filling balloons it probably is.


Jayant Murthy
 

Hydrogen is the way to go. Avoid closed spaces and sparks!
Jayant

On Thursday, July 23, 2020, 11:30:40 PM GMT+5:30, Larry <larry.phegley@...> wrote:


I called and he assured me it was pure helium.  ???  I can't see another explanation why it didn't lift.  Anyway after checking the cost of gas and the cost of conversion ....  Hydrogen here we come

Larry


On Mon, Jul 20, 2020 at 8:39 PM steve potter <spotterotter@...> wrote:
I ran into that with a tank from oxarc, entire s cyl and it didn't lift off the ground and by the calculations we did the s cyl should of been a couple of extra cubic feet. It was great that a fellow ham invited lived about a quarter mile away from the launch site and had a tank at his house. He's not even into balloons but apparently we are all a bit different than the rest of the world.

On Mon, Jul 20, 2020, 11:40 AM K. Mark Caviezel via groups.io <kmcaviezel=yahoo.com@groups.io> wrote:
Caution:
I have encountered at least two industrial gas suppliers that offer lower cost 'balloon grade helium' which is not 99% or better helium.(!)  It is 30%-40% nitrogen.  The thought and rationale is that for normal party balloons, the inclusion of lower cost nitrogen allows persons to fully inflate party balloons, they'll float just fine and a bit cheaper than going with pure helium.  And this will very seriously screw up lift and burst calculations if you use it in a high altitude balloon. I've never used it.  But both times it was offered to me it took a surprising amount of dialog with the industrial gas guys to suss out that it is a 60-40 or 70-30% mix of helium and nitrogen. I don't necessarily fault the guys working at the industrial gas suppliers, they've undoubtedly been briefed that their balloon grade helium is the best stuff for filling balloons.  For 99+% of their customers that are filling balloons it probably is.