# How do I detect Hydrogen (efficiently and cheaply?)

1. Apr 2, 2013

### marshallmeyer1

Hi guys, a buddy of mine and I are high school students and we are attempting to create a lattice fusion reactor using deuterium heavy water. However, know that there are ways to detect oxygen, carbon, etc... but how would one detect hydrogen or helium?

Thanks

2. Apr 4, 2013

### Staff: Mentor

Lattice fusion? Are you referring to the 'Cold Fusion' experiments done back in the late 80's? If so, why are you even attempting something that has been proven false time and time again?

3. Apr 5, 2013

### jim hardy

what concentration? In how much volume?

The pressure generated by a dead-headed centrifugal pump is in proportion to the density of the fluid being pumped. Our main generator gas monitor was a simple impeller slightly less than a foot diameter spun at 3600 rpm .

Those dimensions gave , at atmospheric pressure, differential pressure with this really handy property:
The differential when measured in inches of water was numerically equal to $\frac{molecular weight}{10}$.

When filled with pure hydrogen it developed 0.2 inches of water dp.
When filled with dry air it developed 1.8 inches of water.
When filled with pure CO2 it developed 4.4 inches of water.
at one atmosphere.

At higher pressures of course the dp was higher.
So the indicating part of the machine divided dp(inches of water) by absolute pressure (atmospheres) to obtain effective molecular weight.
These calculations were done by a mechanical analog computer, simple levers and linkages and a cam. The needle pointed to divisions on a scale marked:
100% H2 at one end,
100%CO2 at other,
% mix in between.

I don't think this approach would let you distinguish between Hydrogen and Helium mixed with air
but it'll sure notice when a lighter gas shows up in a heavy one.
Of course our generator ran with a hydrogen fill at 75psig(~6 atmospheres absolute) so we were watching for heavier gas showing up in a light one.

Just wanted to make you aware of a mechanical approach that I thought was clever.
It had the advantages of no fussy chemical cells to keep clean, and even if it got flooded with oil it'd pump itself dry and resume working.
Too simple to not work -- Wish i'd thought of it first!

Last edited: Apr 5, 2013
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