Draught testing challenge

[phizz4]

Cannabis smoker at one end, sniffer dog at the other?

 

[digscaves]

How about using some poly sheet and a large fan at one end or the other to try to engineer a draught reversal? Only a small change in pressure may be needed and no fumes to worry about other than from your generator for the fan.

 

[Graigwen]

Some time before the COVID crisis I had the idea of doing a long range (about 2Km) odour trace into Ogof Draenen using Ethanethiol, commonly known as ethyl mercaptan. This was a bit tricky as the insertion site only had a big inward draught for a short period of the year, and the dilution estimates were a bit problematical. The idea foundered as no supplier would sell the substance without me having a VAT registration number.

 

[shotlighter]

Some time before the COVID crisis I had the idea of doing a long range (about 2Km) odour trace into Ogof Draenen using Ethanethiol, commonly known as ethyl mercaptan. This was a bit tricky as the insertion site only had a big inward draught for a short period of the year, and the dilution estimates were a bit problematical. The idea foundered as no supplier would sell the substance without me having a VAT registration number.

That stuffs evil. Your problem would probably be finding somewhere that you couldn't smell it!
Mind you, think of all the new entrances you'd have dug by Nat. Grid, looking for the leak. 

 

[alastairgott]

Sniffer dogs?

 

[yrammy]

We used joss sticks in Maypole inlet (outlet)  -

 

[oldfart]

You could ask one of those nice ayatollahs in Iran for some uranium hexafluoride. Detection would be easy.

 

[aardgoose]

Sadly UF6 is solid at cave temperatures.

Trained bats?

For the sniffer dog scenario, you could use a dog trained for detecting corpses, and place a dead body* in the upper entrance.

*Human or otherwise.

 

[alanw]

uranium hexafluoride

Only in UKCaving are you likely to get two references to uranium hexafluoride in two threads within 24 hours.

See my post yesterday https://ukcaving.com/board/index.php?topic=28277.0

and four pages later in Otto Frisch's autobiography:
"[Sir James Chadwick] had asked [ICI] about the possibility of producing uranium hexafluoride, the only known gaseous compound of uranium known to be stable enough to be put in a Clusius tube"

(A "Clusius tube" is the apparatus Otto Frisch was using for separating isotopes using "heat and gravity")

 

[braveduck]

Still think Old Spice aftershave is the safest bet ,should be able to smell
it 10 miles away ! 

 

[pwhole]

There's always the great smell of Brut. Then you just need a 'dolly bird' as a detector. 'Splash it all over, eh Henry?!'

https://www.youtube.com/watch?v=HZcxM_t2C1s

 

[paul]

[gmod]Let's try an keep on topic please[/gmod]

 

[crickleymal]

It's also heavier than air and will settle in any hollows...

sorry but that is incorrect.  Badino at https://caves.org/pub/journal/PDF/v71/cave-71-01-100.pdf provides a readable (not much maths) explanation of why not.  Alternatively if SF6 (molecular weight 146) did settle out, then we would all be dead because xenon (molecular weight 131) in the air would also settle out.  The key mitigating factors are drafts and thermal currents which mix the air sufficiently to stop such stratification. 

The simple explanation for CO2 apparently ponding is because it is being evolved in the zone and is not be diffused away fast enough.  The same would be true around the release point of any gas.  But release volume dependent, beyond a certain distance only dilution will occur.

But when you extract it from a waveguide into a bin bag ( as we used to do) you could see that the bin bag was heavier than air. It reacted very differently to a bin bag full of air or one full of methane. Plus the machine manufacturers issue warnings about working in pits under the machines because of the dangers of SF6 pooling in such spaces.

 

[jonj]

Mine safety systems use Ethyl Mercaptan as a stench gas to warn of the necessity to evacuate or move to a miners refuge

J

 

[Pitlamp]

Thanks jonj - I didn't know that. Makes sense, knowing that mercaptons are among the smelliest compounds known to man.

 

[ChrisJC]

The idea foundered as no supplier would sell the substance without me having a VAT registration number.

I've got the VAT number... 

Chris.

 

[thehungrytroglobite]

There are two caves a couple of kilometres apart. One draughts inwards in hot weather and the other (at lower level) draughts out. It would be useful to know if there is an air flow connection between the two caves.

Can anyone think of a way of labelling the inflowing air in such a way that it could be detected at the outwards draughting cave (in the manner of water tracing)?

eat a ton of baked beans, go inside, fart, then have a couple people on the outside sniffing for any bean-reminiscent odours

 

[Graigwen]

The idea foundered as no supplier would sell the substance without me having a VAT registration number.

I've got the VAT number... 

Chris.

I do think the odour tracing should undergo a proper trial if someone can get hold of the mercapten. I mentioned the idea to John Gunn a couple of years ago regarding Draenen tracing as we found a suitable (in my opinion) injection site a few years ago which could not be made accessible for humans. I was thinking a couple of mol would possibly be sufficient for several tests.

(The plan was to do offsite dilution and inject about 5l from the open air into a draughting orifice via a funnel and pipe to avoid any possible surface contamination.).

.

 

[Pitlamp]

There are two caves a couple of kilometres apart. One draughts inwards in hot weather and the other (at lower level) draughts out. It would be useful to know if there is an air flow connection between the two caves.

Can anyone think of a way of labelling the inflowing air in such a way that it could be detected at the outwards draughting cave (in the manner of water tracing)?

eat a ton of baked beans, go inside, fart, then have a couple people on the outside sniffing for any bean-reminiscent odours

I just knew someone would make that suggestion sooner or later! 

 

[zzzzzzed]

Sniffer dogs?

I've often wondered about training a dog to detect drafts from caves.  You could then get them to go round the moors sniffing every shakehole.

They would obviously need to be trained to detect connecting drafts too.

Do we have any volunteers to be the CNCC dog handler?