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# Helium to reduce weight

## Helium to reduce weight

(OP)
Anyone have any experience filling a void in a fixture with helium to reduce the load the operator must lift when handling the fixture? Just a stupid Idea I had, anyone know for sure that it will, or will not work?

### RE: Helium to reduce weight

Yes, it's a stupid idea.  Do the math yourself.  How much does air weigh?

I'll give you a hint; 1.2 kg/m^3

### RE: Helium to reduce weight

I'll reiterate IRstuff's comments, but also add the fact that you are going to have to work out bouyancy calculations to determine how much benefit you get by adding a lighter than air gas into a void.

Right now, just assuming that you are using something "light" like aluminum (as opposed to steel), I would consider the affect of the gas insignificant and remove it from the equation in order to make the solution simpler.

To put it more conceptually, look at how much helium you have to add to a few-mils-thick rubber balloon before it actually floats.

Rubber 1.25 g/cc
Alum 2.7 g/cc
Steel 7.9 g/cc

You'd need a heck of a lot of helium to lift an aluminum balloon, much less steel.

--Scott
http://wertel.eng.pro

### RE: Helium to reduce weight

Ha! I wasn't even going to go there!

Just do the dead weight.  You need to have a cubic meter of gas space to save 1 kg in weight, that's 2.2 lb for us in the US.  The amount of work required to make it sufficient gas tight will probably negate any weight savings there might have been.

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