Heating a Gas in Air

"The gas is higher density then air and as it leaks if the gas leak can be heated it is more visible to detection."

Since the gas has to be under pressure to leak into the atmosphere it will mix rapidly with the atmosphere. No time nor method available to heat it as it leaks.

Reconsider your question and restate it.

It might be possible to use a single frequency light source (dye laser?) of a frequency tuned to be absorbed by the gas rather than the surrounding air. It would help to know what the gas is. The concentration of the gas would have to be fairly high though. Not an easy problem to solve.

A specific example might be helpful in order to arrive at a generalized solution.

Can't say I've ever done this for moving gasses. Heating a contained gas is simple enough using a tuned dye laser. Heating specific tissue with a tuned laser is a typical surgical procedure now. Like I said, it might work. It's the only thing I can think of.

Generally speaking, leaks cause high frequency noise, this is the preferred method, make an electronic "ear" to search.

If the gas is not explosive, some leaks can be best found by burning say methylated spirits in a blowtorch and using a sampling tube to find the leak by noting the gas flame color changes.....

I have done both!! and I am sure that lots of other methods exist!!! Do you know the one for explosive gases, a lighted match!!! Only joking!!!!

Why not use the good ol' sniffer such as Matheson makes? Of course there is mass spectrometry such as in the use of a helium leak detector. (please do not tell me about controlled leaks and how a HLD would not work here...I know) The point is MS.

Attaching a sniffer as a payload to a standard RC device for distant analysis?

More specifics please. Are we talking about Ar or Ph₃?

cr3