Author Topic: Help - leaking SCBA fill station (Read 1382 times))

keefd · « **on:** May 10, 2020, 02:14:55 PM »

So I need some help figuring this out.
I got a used SCBA tank and a new fill station. The fill station is a CGA347 hand-tighten version.

The problem is there is a leak right at the CGA347 connection. I wanted to do a short test fill (below 100PSI) to check for leaks, and I was surprised there is a leak right at the SCBA valve/fill station interface.

I swapped o-rings and I tried tightening it lightly, snug, and really cranking on it - it leaks before the compressor and fill station gauges even move.
I rotated the fill station 180 degrees and the leak seemed to follow, as in air blows out the same spot in relation to the fill station. This leads me to believe the fill station is at fault, but there are no nicks or dents and the orange o-ring is new.

I will take the tank to a testing place tomorrow, but I wanted to see if there's something I could figure out today.

Back_Roads · « **Reply #1 on:** May 10, 2020, 02:29:39 PM »

Hmm sure you closed the bleed valve? here is a picture show us where it leaks

One other thing is there a seal typically some harder white plastic, that seals under the bleed valve. Also make sure all threaded connections are firmly snug.

keefd · « **Reply #2 on:** May 10, 2020, 03:18:42 PM »

See picture, you may have to expand it.

It's not the bleed valve as I can close that and stop the airflow easily.

triggertreat · « **Reply #3 on:** May 10, 2020, 03:28:23 PM »

It's all about that O-ring and the nut and tank threads to seal off that area. Maybe the area the O-ring mates to inside the tank valve has a nick the O-ring can't fully cover now???

AGEnthused2 · « **Reply #4 on:** May 10, 2020, 06:07:33 PM »

Do you tighten with a wrench?
All three of mine have leaked until I snugged with a wrench.

keefd · « **Reply #5 on:** May 10, 2020, 06:13:17 PM »

Quote from: AGEnthused2 on May 10, 2020, 06:07:33 PM

Do you tighten with a wrench?
All three of mine have leaked until I snugged with a wrench.

Do you mean at the SCBA tank valve? No, didn't try that as the fill station is supposed to be the hand-tight version.
Should I? I don't want to damage anything.

Wayne52 · « **Reply #6 on:** May 10, 2020, 06:32:24 PM »

Personally I opted for the wrench tighten connector when I put my adapter together. Never leaking in over 3 years now.

I have replaced the cheap Chinese fill whip with a much better one and have added a better bigger gauge.

keefd · « **Reply #7 on:** May 10, 2020, 06:55:16 PM »

I'm thinking this fill station is a lost cause. If the tank tests okay, I'll probably replace the valve with an integrated foster connection/fill hose.
If the tank passes, I might build my own.

Does anyone know what internal threading is on a Draeger 45min/68cf SCBA tank? I think it's M18x1.5, but I couldn't find anything conclusive by googling.

AGEnthused2 · « **Reply #8 on:** May 10, 2020, 08:08:27 PM »

Yes tighten the nut on the adapter with a wrench, it’s just to snug it.
Before getting my first tank and adapter I watched videos, and from what I remember the fittings were snugged with a wrench.
Hand tight really doesn’t exist with high pressure.

VaporTrail · « **Reply #9 on:** May 10, 2020, 10:08:59 PM »

My Omega tank was leaking out of the bleed valve. I tried to remove it, but the pressure gauge was in the way. Didn't know if I could unscrew the pressure gauge while the tank was holding a charge, so I drained it. Turns out both orings on the bleed valve were broken. Replaced and now it fills and holds pressure fine. Called AoA and asked if I needed to drain the tank to remove the pressure gauge, and they said as long as the valve is closed, I can remove it. Replacement gauge arrived at the USPS Hub this morning, so when I get home, I'll replace.

After draining the tank, I decided to inspect the inside so I popped off the top. Replaced the oring at the neck and hand tightened it. Gave it a little love tap from a rubber mallet and so far so good.

Maybe yours just needs a little love thump? You can also check the orings for proper fitment. That happened the first time I drained the tank to take a look inside.

Franklink · « **Reply #10 on:** May 10, 2020, 10:19:29 PM »

https://www.airgunnation.com/topic/fill-station-oring/

I just went through this.

I've since been told that a 011 oring is likely a better fit. Airgunning friend was able to solve the same problem with the same eBay fill station with that size oring. I purchased some, but have yet to try them out.

These fill stations seem to be pretty high quality, considering the price. Just that pesky leak. If the 011 fixes the problem, I'm going to pass this station on to a friend with a wrench tight station that told me he'd would like a hand tight one.

keefd · « **Reply #11 on:** May 10, 2020, 11:13:49 PM »

I figured it out.
Or at least I think I did.

So I have a couple spare CO2 CGA-320 nuts in my junk drawers. For gits&shiggles I tried to see if it would fit the SCBA CGA-347 threads. Well, it does so I tried it with the CGA-347 nipple.

Wouldn't you know it, the threads on the nut are too short, but it did let me see one of the "safety holes" that the CGA-347 nut covered up. So I tightened it down a bit.
I looked up into the "safety hole" and guess what I see? Yeah, part of the orange o-ring.

It seems that either the "safety holes" are cutting the o-ring, there's an unsupported part of the o-ring where the holes are, or when the o-ring is compressed it squishes out the safety holes a little, causing the leak. The CGA-347 nut's skirt is super deep so I couldn't tell the safety holes were the cause of the leak originally.

edit - I just looked at it again, yep - the o-ring is definitely being squished out and looking at it later, it's getting cut. I know o-rings don't work unless fully supported, and this one clearly wasn't.

I'm debating going to a welding shop tomorrow and getting a solid brass wrench-tighten CGA-347 fitting, or just replacing the whole SCBA tank valve.
Does anyone know Draeger tank valve thread size? M18x1.5?

Buldawg76 · « **Reply #12 on:** May 11, 2020, 02:32:36 AM »

Every CGA 347 fitting I have ever seen does not have any o ring or delrin seal on the end that fits inside the tanks valve, it should have a round steel or brass end on the nipple that goes into the tank valve and seals metal to metal by the nipple and seat in the tank valve being the exact same contours. The hand tight fitting is just that hand tight with no wrench needed. The hole in the thread of the tank valves is a safety bleed if you were to loosen the hand tight fitting without bleeding the fill whip so it allows all pressure to escape before the hand tight fitting completely unthreads.

Some cheap chinese hand tight fill assembly do not have a correct mating contour to seal in the cga 347 tanks valve or the nipple is just shy of being long enough to contact the bottom of the tank valves seat to create a seal. The hand tight nut could be bottoming out on the tank valve thread before the nipple fully contacts the valve seat allowing for a small leak. If you can rotate the fill gauge/bleed valve assembly with the hand tight nut tight its not fully seating.

I believe you have mismatched parts .

BD

Wayne52 · « **Reply #13 on:** May 11, 2020, 02:58:20 AM »

Both my CGA fittings work well but both are made in USA fittings too.

keefd · « **Reply #14 on:** May 11, 2020, 04:17:07 AM »

The nut's not bottoming out, I can still see more threads. If I remove the nipple and just thread the nut, it goes farther in. The nipple is long enough, there's about 3/32" clearance when the nipple touches the bottom of the CGA 347 connector.

I think the fill nipple not having the correct contour is the issue. Or the tank's connector was damaged inside, sand or dust maybe? It came from the Phoenix FD. When I used a shorter nut, I can clearly see the o-ring being squished out the safety hole. Enough to damage it, but I couldn't tighten it any further even when I got out my biggest slip-joint pliers and went ham on it. Even just hand tight the assembly doesn't move at all.

I'll have the tank inspected at a fire safety place and see what they say.

KnifeMaker · « **Reply #15 on:** May 11, 2020, 05:02:07 AM »

Go to the hardware store and pick up a nylon washer that will seat in the bottom of the tank valve opening, and screw the hand fitting in tight. O rings are far too soft for his. Scott bottle fitting have the nylon washer built into the hand tight fitting.

Knife

Buldawg76 · « **Reply #16 on:** May 11, 2020, 11:56:51 AM »

Yea the contours may be the issue and as for using a delrin washer or o ring while it may work it will fail in the long term. I prefer the metal to metal type of CGA 347 fittings as they will last a lifetime without issue. I believe that there are two types of scba tank fitting in use that are CGA 347 and CGA 346 which do have slightly different contours and sealing designs.

BD

keefd · « **Reply #17 on:** May 11, 2020, 01:07:50 PM »

Well, this is disturbing.

While trying to deburr the o-ring seat edges, I found a hairline crack on the fill station CGA 347 nipple.

There was 1 spot that seemingly wouldn't polish up, and when I got my glasses out and looked at it under a flashlight, there was a dark line going from the nipple contact area all the way to the NPT threads. I can feel it by scratching my nail over it.
I can see the crack on the inside and outside of the tube. That would explain why it felt like air was leaking out the side of the tube, because it was.

And apparently CGA 347 nipples are as rare as hen's teeth here in Omaha.

Sorry for the roller coaster ride. I was troubleshooting under the assumption that something like a new, cracked stainless fitting just wouldn't happen.

I'm just glad I didn't try to run it up to working pressure. It may have leaked out too fast to pressurize, or it might have ruptured.

triggertreat · « **Reply #18 on:** May 11, 2020, 05:59:25 PM »

Quote from: keefd on May 11, 2020, 01:07:50 PM

Well, this is disturbing.

While trying to deburr the o-ring seat edges, I found a hairline crack on the fill station CGA 347 nipple.

There was 1 spot that seemingly wouldn't polish up, and when I got my glasses out and looked at it under a flashlight, there was a dark line going from the nipple contact area all the way to the NPT threads. I can feel it by scratching my nail over it.
I can see the crack on the inside and outside of the tube. That would explain why it felt like air was leaking out the side of the tube, because it was.

And apparently CGA 347 nipples are as rare as hen's teeth here in Omaha.

Sorry for the roller coaster ride. I was troubleshooting under the assumption that something like a new, cracked stainless fitting just wouldn't happen.

I'm just glad I didn't try to run it up to working pressure. It may have leaked out too fast to pressurize, or it might have ruptured.

Probably a blessing from above. A hairline crack can be very dangerous at those pressures.

Buldawg76 · « **Reply #19 on:** May 12, 2020, 02:11:54 AM »

https://www.augustindustries.com/product/cga-347-nut-nipple/

https://www.augustindustries.com/product/cga-347-stainless-nut-nipple/

http://www.northshorecompressor.com/products/CGA-347-Hand-tight-nut-and-nipple.html

http://www.northshorecompressor.com/products/CGA-347-wrench-tight-nut-and-nipple.html

http://www.northshorecompressor.com/copy-of-cga-347-wrench-tight-nipple/

http://www.northshorecompressor.com/products/CGA-347--Hand-tight-nipple.html

http://www.northshorecompressor.com/products/CGA-347-wrench-tight-nipple.html

Take your pick, the last 3 should all work with your current fill station.

BD

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Help - leaking SCBA fill station

Author Topic: Help - leaking SCBA fill station (Read 1382 times))

AGEnthused2

AGEnthused2