Today I just got my CO2 tank refilled at my LFS and at the end the guy told me 'not to loose this' and handed me an o-ring and says it was on my tank when I gave it to him.

I got home and placed the O-ring around the nipple on the regulator and screwed on the tank. Immediately I could hear a loud hiss and could feel the gas leaking around the connection. I tried to tighten the connection but no go. I then tried to pull get the o-ring out (I thinking that it may had been installed upside down or the wrong location) but it won't come out of it's recess.

From the gauge it shows that it can only hold just under 500psi.

Having not really noticed this o-ring before and cannot find any manuals online, is the o-ring the problem and how do I get a replacement (or even get it out)?

Note: Regulator is an Ista Twin Mini Gauge Vertical CO2 Controller (with Solenoid) http://www.istaproducts.com/product/co2-controller-mini-gauge-vertical/

Found out today it was a bit of a false alarm. I was a bit lazy when I screwed it back on. Turns out when you put the o-ring back on when the solenoid is engaged it goes further into the recess so it doesn't seal. When it switched off the o-ring came back out and sealed. It now seals fine and gauge shows 900psi.

It's almost been a year but it hasn't been smooth sailing.

The following CO2 refill wouldn't seal and I tried to find similar sized o-rings from Bunnings. At the start they didn't seal so I ordered nylon washers from eBay (18mm x 11mm) which were advertised for CO2 regulators. They didn't seal either. They were worst. I assume they don't work with Ista because you can only hand tighten and the fact that the Ista bottle the top isn't flat (has a groove which looks like it's for an O-ring). I popped in an O-ring from Bunnings again and it actually sealed. Not sure why but it worked for about 3 refills.

Just got another refill and attempted to pressure test the connection (solenoid off, opened the tank's valve to pressure up against the solenoid, then close the tank valve and monitor the pressure). It would go to 0psi within 3-5hrs. I changed out the o-ring and tried again but didn't work.

So I ordered o-rings which were described as "CO2PRO and DICI replacement oring for seal between regulator and cylinder valve. This style of oring will suit most types of regulators on the market". It was slightly larger than the other O-rings I had but no issues fitting into the recess in the regulator. However on the pressure test it would drop to 500psi within a few hours and to 0psi over night.

I'm not sure what to do now. I'm thinking about trying to find a rubber gasket of 18x11mm that way it covers the top surface of the sealing face of the tank. But having installed the nylon washer/gasket of the same size it was a pain to remove.

I'm almost at a point where I should just buy a new regulator. One that uses either the nylon washer or the other o-rings I found.

I've been searching the web for o-ring recommendations for this regulator but it's been difficult. This week I'm going to try and get some #111 O-rings (some mentioned on another forum), also something that fit in the groove of the tank sealing face, and maybe the rubber gasket/washer I talked about.

Does anyone have any recommendations (O-ring or regulators)? 

FWIW, the flat hard plastic washer that seals up against the face of the bottle outlet is the Australian standard fitting as is the more bullet-proof option.  There are a few people posting on other forums about the Ista leaking and requiring new o-rings as I'm sure you've found.   For either type, the recommendation is that a new seal is used every time the regulator is fitted to the bottle but most people spin it out a bit longer.  Once the o-ring has distorted or cracked its useless.

The one oddity in your post is the mention of groves on the bottle outlet.  The face of the outlet should be smooth and I've not seen any system where an o-ring is fitted to the bottle.  Perhaps post a pic of the bottle outlet.  What sort of bottle is it?

The fault might lie there.

Hi Grubs,

Photo of the outlet shown. The groove is quite small. Not very deep or wide (<1mm). It is an Ista tank.

I've also attached photos of the o-rings/washer I have used.

The two black ones are from Bunnings. The smaller of the black has 'worked' in the past. It fits snuggly around the nipple/spigot of the regulator. The larger sits on the inside of the groove. The washer is from Fleabay which easily covers the sealing area but I can only hand tighten the connection meaning it won't seal properly. The white/transparent o-ring is the latest described to work with Dici and CO2PRO regulators. It's size is between the two black ones. I also found an o-ring in my kit that sits directly over the top the groover which I'm currently testing.

Hope this helps.

 

 

 

I think you just need a "fatter" o-ring the diameter of the smaller black one.

compare to :

http://www.co2art.co.uk/collections/adapters/products/o-ring-replacement-for-co2-aquarium-regulator

(finding one locally will be a lot faster than postage from UK)

or use the smaller white one and tweak up the reg with some vice grips.

Last week I got some time to go around town to find O-rings. First two places (which I won't name) were useless. I went to Allied Bearings and Seals in Rocklea, Brisbane. The guy there was really helpful. I did end up getting #111 O-rings. They turned out to have the same ID as the Bunnings O-ring and the same OD as the white O-ring. Essentially they were fatter. Got 6 O-rings for $4.

I pressured tested the connection the first time overnight and it was solid. Then over the week I continued to pressure test the connection overnight (turning off the tap on the cylinder at night and opening it back up in the morning). It was perfectly fine. It's being going well for the week now. I just leave the tap open and let it seal up against the solenoid.

I'm very happy with this result.

For anyone else who's looking for O-rings for their Ista regulator, use a #111.

 

 

 

 

 

CO2 is hard on any number of plastics - you will want to check that those o-rings are nitrile or PTFE or they will end up cracking. At $4 for a package of six, I would wonder. 

On Saturday, June 18, 2016 at 6:32 PM, Josho said:

Last week I got some time to go around town to find O-rings. First two places (which I won't name) were useless. I went to Allied Bearings and Seals in Rocklea, Brisbane. The guy there was really helpful. I did end up getting #111 O-rings. They turned out to have the same ID as the Bunnings O-ring and the same OD as the white O-ring. Essentially they were fatter. Got 6 O-rings for $4.

I pressured tested the connection the first time overnight and it was solid. Then over the week I continued to pressure test the connection overnight (turning off the tap on the cylinder at night and opening it back up in the morning). It was perfectly fine. It's being going well for the week now. I just leave the tap open and let it seal up against the solenoid.

I'm very happy with this result.

For anyone else who's looking for O-rings for their Ista regulator, use a #111.

 

 

 

 

 

So I got the #111 o-rings from the same place you did in Rocklea and they are identical to the garden tap o-rings from Bunnings. (photo attached) 

I have to use 2 o-rings otherwise the thread gets to the end before it tightens. 

Im using a ista 0.82L cylinder . 

I'll get mine refilled and do the pressure test. This time I'll use plumbers tape