how much does air weigh?

[Don Burke]

So does Nitrox weigh less?

Normally a whisker more, but not enough for most to notice.

what about tri-mix? (it does have helium in it).

It weighs less for most mixes; it would be difficult to notice it in air.

 

[omar]

Just to be a physics nit...

pounds is a measure of force (i.e. mass * acceleration) the slug is the measure of mass in imperial units. This is another wonderful example of why SI units make more sense.

Now taking this a little bit further [in deference to the pranksters] ... if you dive over an area where there is a gravity anomaly the “weight” of the tanks and air will be more or less depending upon the type of gravity anomaly.

But anyway the density of dry air for us imperial oafs is 0.08071 lb/cuft. at 0 degC; 760 mmHg ---> 1.2928 g/L

 

[Rick Murchison]

Normally a whisker more (Nitrox), but not enough for most to notice.
(Trimix) weighs less for most mixes; it would be difficult to notice it in air.

Just so.
Rick

 

[Rick Murchison]

Just to be a physics nit...

pounds is a measure of force (i.e. mass * acceleration) the slug is the measure of mass in imperial units. This is another wonderful example of why SI units make more sense.

Now taking this a little bit further [in deference to the pranksters] ... if you dive over an area where there is a gravity anomaly the “weight” of the tanks and air will be more or less depending upon the type of gravity anomaly.

But anyway the density of dry air for us imperial oafs is 0.08071 lb/cuft. at 0 degC; 760 mmHg ---> 1.2928 g/L

Omar's really shaving nits here and he is correct. The apparent discrepancy in mass from what I posted above is because the molecular weight (and when we use the popular term "molecular weight" we really mean average molecular mass, which takes into account the various isotopes and their percentages that occur in nature) of Nitrogen and Oxygen in the air is slightly greater than their respective atomic numbers would indicate.
Are we havin' fun yet???
I am!
Rick

 

[dive_lover88]

do you need to factor in the gravitational pull of the earth?

 

[OHGoDive]

If you're going to do that, maybe we should measure the weight of air in a vacuum.

 

[dive_lover88]

maybe we could do both and see what is the difference.

 

[Rick Murchison]

do you need to factor in the gravitational pull of the earth?

It's included in the definition of a pound, so yes, we do, but not as an addition to what we've already done since it's already in there
Rick

 

[Warren_L]

So does Nitrox weigh less?

what about tri-mix? (it does have helium in it).

Depends on the mix of nitrox. Oxygen weighs more than nitrogen, so enriched air should weigh more than air, and hypoxic mixes should weigh less.

 

[H2Andy]

So does Nitrox weigh less?

what about tri-mix? (it does have helium in it).

without reading the responses, i would guess that yes, there is a difference in weight as the gas composition changes

but for practical purposes, it's the same thing


[edit] ok ... i more or less got it right