Helium Purity - RC Groups
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Jan 25, 2013, 04:38 AM
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Helium Purity

Im on my 3rd season with a 12-13 ft ad blimp.I fly for a college basketball team.
First 2 years I had Praxair Ultralift balloon gas.Good stuff.I started the season with quite a bit of ballast and its stored onsite inflated for the whole season.Im sure as those who operate this way know that throughout the season and over time it requires topping off.I discovered early on that apparently that there is a certain amount of other gas that finds its way into the envelope and the helium gets contaminated even if your careful to purge your fill lines.Lift is lost and small amounts of ballast is removed to maintain correct buoyancy over time.
With the balloon gas I started with maybe 10-11 ozs of ballast to start and ended up with maybe 4 after 3 1/2 months.
This year Praxair is no longer supplying and the gas they got me is I think just welding grade or something.Its obviously not as pure and I started with a little over 6 ozs of ballast with a fresh fill.Im sure you see where Im going with this.
Im 2/3 through the season and Im down to a couple ozs.Its gonna be close but I may run out of lift at the rate Im going before the end of season in another month.
Ive heard of burping by standing on end and letting some heavy gas settle and then draining and purging.
How effective is this? A rough idea of percent of total volume that may separate as heavy and be able to get purged without blowing alot of extra off? Im about 180-190cu/ft total.Im thinking if I could hope for 1% I might be able to gain a couple ozs of lift back and make it through the last couple weeks if it comes to that without having to purge a bunch and need to request some more from the supplier.
We know about supply issues and that is taken care of by the org that hires me to fly and its my understanding it was a battle just to get the 400cu ft I told them I used the last 2 seasons.
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Jan 25, 2013, 01:00 PM
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Ed Couch's Avatar
The best grade gas is utilized in medical and in welding. Balloon grade gas does have a percentage of air in it and definitely is noticed. One of the ways we save helium is partially inflating the ship with helium until it lifts the vehicles with everything on board including about eight ounces of ballast. At that point we use a small pump to pump air into the envelope until it smooths out and fully inflates. The new balloons leak very little and we may go 4/5 games before any helium has to be added. Due to varience of temperatures in the buildings especially you may have to add air to fill the balloon back out especially if you are working hockey and basketball venues in same building. Just something that happens and not to worry. If the below becomes to heavy burping is a common correction. Nose is held high for several minutes to let gas to go to top of balloon and then the aft plug is removed and let the balloon vent the heavy air out. After a couple of minutes of venting the envelope is again filled to shape with helium and life goes on. Just part of business. Once in a blue moon you may have to empty the vehicle and refill from the beginning. Its rare but we have had it happen. Just part of doing business. One of the funny ways the guys use to burp is to run a tube about five foot long to the bottom of the balloon and hook that up to a vac. He then fires it off and let it pull the air out of the bottom of the balloon. Every couple of minutes he will take a snort of the outgoing air and speak, if voice is squeaky he continues until it is not. Also the pump will run higher when drawing helium out instead of air and it can difinitely be heard when the pump speeds up. Now that all the tricks you get from me today. As the man said "It works for me".
Jan 25, 2013, 03:08 PM
Registered User
Very good.Thanks for the reply.

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