Gas leak detector spray

[Dr Mike Oxgreen]

I need to figure out where I've got a gas leak - but I'm talking about CO2 leaking from a Sodastream cylinder connected to a regulator (this is for a fish tank).

I connected everything up a couple of weeks ago, but with the CO2 output switched off. I noticed a few days ago that the pressure gauges were reading zero; I weighed the cylinder and it was down to its empty weight.

I've replaced the cylinder and reconnected, doing the nut up as tightly as I can. But still the cylinder lost about 60g of weight overnight.

So I need to figure out where it's leaking. I can't immerse it in water without tipping the cylinder on its side, which will tip the liquid CO2 and cause it to cover whichever part is leaking - so I assume this would give a "false negative". I've tried squirting the connections with "shower shine" stuff to see if it bubbled, but that didn't really work (it just ran off too quickly).

So what about gas leak detector spray? Would that detect ANY type of escaping gas, or is it specific to "Gas" with a capital G?

Any suggestions gratefully received!

Edited by Dr Mike Oxgreen on Sunday 15th November 08:03

[Gingerbread Man]

Spray bottle. Water. Few drops of washing up liquid.

Spray on the joint, if leaking, it'll bubble.

[Dr Mike Oxgreen]

I'll try it, but when I used the shower shine stuff it just ran off too quickly. Perhaps soapy water will work better.

My suspicion is that it's leaking from the joint between the cylinder and the adapter that converts the thread to the right size for the regulator. When I screw the adapter onto the cylinder, there's hardly any resistance before I reach the end of the threads, which makes me wonder if it's not screwing tightly enough onto the nylon washer inside the threaded part.

I've never used pressurised CO2 on a fish tank before, so it's all new to me.

Edited by Dr Mike Oxgreen on Sunday 15th November 08:13

[Magic919]

I'm not convinced that putting it in water is a bad idea.

[Dr Mike Oxgreen]

Magic919 said:

I'm not convinced that putting it in water is a bad idea.

Yes, I guess it's worth a try. I'll dunk it in the bath and see what happens.

[Rickyy]

You can buy gas leak detector spray from screwfix, although you often get varied results from it. It doesn't always bubble up on small leaks.

[Mr Pointy]

Try neat washing up liquid. Being a lot thicker it tends to stay in place rather than all slip away.

[Gingerbread Man]

You can get more of a foam gas detector.

[dudleybloke]

A 50/50 mix of washing up liquid and water will do the job.

[Dr Mike Oxgreen]

Aha, yes - thick or even neat washing up liquid might do better.

I'm away from home at the moment but will try this afternoon.

[Pagey]

Dr Mike Oxgreen said:

I'll try it, but when I used the shower shine stuff it just ran off too quickly. Perhaps soapy water will work better.

My suspicion is that it's leaking from the joint between the cylinder and the adapter that converts the thread to the right size for the regulator. When I screw the adapter onto the cylinder, there's hardly any resistance before I reach the end of the threads, which makes me wonder if it's not screwing tightly enough onto the nylon washer inside the threaded part.

I've never used pressurised CO2 on a fish tank before, so it's all new to me.

Edited by Dr Mike Oxgreen on Sunday 15th November 08:13

Try some PTFE tape on the threads

[p1esk]

Pagey said:

Dr Mike Oxgreen said:

I'll try it, but when I used the shower shine stuff it just ran off too quickly. Perhaps soapy water will work better.

My suspicion is that it's leaking from the joint between the cylinder and the adapter that converts the thread to the right size for the regulator. When I screw the adapter onto the cylinder, there's hardly any resistance before I reach the end of the threads, which makes me wonder if it's not screwing tightly enough onto the nylon washer inside the threaded part.

I've never used pressurised CO2 on a fish tank before, so it's all new to me.

Edited by Dr Mike Oxgreen on Sunday 15th November 08:13

Try some PTFE tape on the threads

I know that's the modern way of doing it, but when I had a brief flirtation with PTFE tape on normal plumbing joints, I didn't seem to get very good results. From what was said in another recent topic it sounds as you need to use a hell of a lot of tape, a fair amount of which gets squeezed out of the threads IME, so I prefer to use a sealing compound.

[Dr Mike Oxgreen]

PTFE tape sounds like a good idea - thanks for the suggestion!

When I get home I'll weigh the cylinder again and see if it's lost any more weight.

[Dr Mike Oxgreen]

I've arrived home to another completely empty CO2 cylinder. Beginning to think something is faulty.

[Rickyy]

Dr Mike Oxgreen said:

PTFE tape sounds like a good idea - thanks for the suggestion!

When I get home I'll weigh the cylinder again and see if it's lost any more weight.

PTFE tape only works on fittings where the threaded sections actually form the seal, not just provide a clamping force.

If there is a fibre washer in the fitting, I doubt adding PTFE to the threads will make any difference, same goes for adding it to the threads on compression fittings.

[sherman]

Use neat washing up liquid on the birs where you think the leak is. Also the area around the leak may be a bit colder as if the CO2 is coming out at any pressure it will be icing up that area.

[p1esk]

sherman said:

Use neat washing up liquid on the birs where you think the leak is. Also the area around the leak may be a bit colder as if the CO2 is coming out at any pressure it will be icing up that area.

In the absence of proper sealing compound, I use neat washing up liquid on the threads of screwed joints, and around the olive and seating faces on compression couplings. Admittedly it sounds a bit daft, but I find joints seal quite nicely on that basis.

[Mallinson1984]

Not so sure neat washing up liquid will be as effective as diluted solution... I use leak detection fluid alot in my line of work and diuted dolution will find your leak very effectively.

Dilute in a jug and slowly pour over all suspect areas, you only need the residue after most has run straight off to show you the point if failure. Be patient and observe for a few minutes if required although I doubt you'll need to be

[Peanut Gallery]

I would use varying ratios of washing up liquid and water in a spray bottle, till I find a ration that works with that brand of washing up liquid.

Alternatively
Google search for air con leak detector spray

That was the first one that I saw.

Curious side of me wants to know why you are giving the fishes carbon dioxide? - more plants than fishes? Excessive algae growth?

[ColinM50]

Sounds to me as if you've got a seal missing. Should there be a tiny O ring in the valve/connector set up? Maybe take the assembly to your local aquarium shop and ask 'em?