How Miflex HP ruined my dive.

[Ragnar]

I've been a bit concerned since getting the Miflex HP hose just from the looks of it, well today it finally happened. I'd say I only have maybe 30 dives on it so I thought you guys should know that in my opinion there is a genuine design flaw that's different from the previous one where the actual hose let go. In my case the hose is fine, but it let go at a fitting that I wasn't aware was even there and don't think should be.

I had it set up with a boltsnap tied on in the usual place. As has been discussed here, once pressurized the gauge doesn't swivel like it would on an ordinary line, it takes two hands, one to hold the line from twisting and the other to reposition the gauge. BAM!....that's when I found out there is an extra seal hiding in there and that it's not swaged like a normal line! The really bad part is that there is no way to properly tighten that fitting! I have had the Miflex LP lines for much longer and I like them, but there is no way I can recommend the High Pressure lines given this design, I'm switching back to rubber.

 

[Troutmaster]

There has been alot of talk of failures on the DecoStop. Most guys agree the LP hoses are great and the HP hoses suck.

 

[redacted]

It looks like that inner piece unscrewed at least part way before it snapped. Is that correct? I guess the lack of a swivel capability should have been a warning of something wrong. Hopefully the Mfgr or distributor will have something to say.

 

[Ragnar]

It looks like that inner piece unscrewed at least part way before it snapped. Is that correct? I guess the lack of a swivel capability should have been a warning of something wrong. Hopefully the Mfgr or distributor will have something to say.

Kinda. Your right, the inner piece did unscrew causing the leak, but nothing actually broke off. Back at home I was able to put it back together, but there is really no way to tighten it properly, all I could do was take a very small needle nose plier and grab it the best I could. I reassembled it this time with some lock-tite on the threads and did get it to stop leaking, but this design is so flawed I won't be keeping it. Miflex should have spent a lot more time designing a proper swage fitting instead of worrying about making the hose as thin as possible.

The way these don't swivel easily under pressure is common to all of them, it's just that this time it was enough to unscrew that fitting I didn't know was there. For those of you who will continue using these hoses I recommend turning the gauge into the position you want before pressurizing the hose and then not messing with it during the dive. If you can also take it apart and put it back together with lock-tite to keep the thing from unscrewing all the better.

 

[redacted]

Kinda. Your right, the inner piece did unscrew causing the leak, but nothing actually broke off. Back at home I was able to put it back together, but there is really no way to tighten it properly, all I could do was take a very small needle nose plier and grab it the best I could. I reassembled it this time with some lock-tite on the threads and did get it to stop leaking, but this design is so flawed I won't be keeping it. Miflex should have spent a lot more time designing a proper swage fitting instead of worrying about making the hose as thin as possible.

The way these don't swivel easily under pressure is common to all of them, it's just that this time it was enough to unscrew that fitting I didn't know was there. For those of you who will continue using these hoses I recommend turning the gauge into the position you want before pressurizing the hose and then not messing with it during the dive. If you can also take it apart and put it back together with lock-tite to keep the thing from unscrewing all the better.

I suspect you could use an SPG screwed in tightly to hold the two pieces together and then tighten it into the hose. Maybe a little loctite to help hold it. Then you just need to unscrew the SPG.

 

[Ragnar]

I suspect you could use an SPG screwed in tightly to hold the two pieces together and then tighten it into the hose. Maybe a little loctite to help hold it. Then you just need to unscrew the SPG.

That's the first thing I tried, it doesn't work. That middle fitting is free to rotate freely even when the B-nut is tightened to the SPG since it's sealed by an o'ring and not a face seal. And when it came unscrewed there was no immediate way to screw it back in regardless of if there was pressure on the system or not. This design with nothing to lock the threads and no way to tighten the fitting really baffles me.....it's junk. There's no way a design like this would make it past certification in other industries that are more closely controlled.

I guess if you had the male side to the fitting and tightened it to that instead of an SPG you could stop it from rotating and then have something to put a wrench to, but in the end it's just nonsense.

 

[knowone]

Do what awap says using a washer or two between the spg and fitting.

Anyway thanks for the heads up. I'm going to use all rubber from now on.

Oh. Hang on.

I already do.

 

[redacted]

That's the first thing I tried, it doesn't work. That middle fitting is free to rotate freely even when the B-nut is tightened to the SPG since it's sealed by an o'ring and not a face seal. And when it came unscrewed there was no immediate way to screw it back in regardless of if there was pressure on the system or not. This design with nothing to lock the threads and no way to tighten the fitting really baffles me.....it's junk. There's no way a design like this would make it past certification in other industries that are more closely controlled.

I guess if you had the male side to the fitting and tightened it to that instead of an SPG you could stop it from rotating and then have something to put a wrench to, but in the end it's just nonsense.

If the SPG stem is not long enough to engage the fitting, one of these should do the job: http://www.scubaboard.com/forums/do-yourself-diy/354001-tank-equalizer-2-50-a.html

 

[DiveGearExpress]

You do have another option, if you don't care for the standard rubber hoses.

Phantom High Pressure Kevlar Double Braided Hoses


Phantom double braided high pressure hoses have an outer polyester braided cover that is laid over a woven Kevlar layer The Phantom double braided high pressure hose has a typical outside diameter that works better with hose boots and consoles. Every Phantom double braided high pressure hose is tested to 5000 psi and a rated burst strength of 22000 PSI. Fittings are made from quality chrome-plated brass. The typical high-pressure hose is a 7/16-inch male at the end that screws into the first stage HP port and a 7/16-inch female at the end that screws on to the SPG. Length is measured in inches, from end to end of hose, including the fittings and their threads.


Hoses for SCUBA - Dive Gear Express

 

[danvolker]

You do have another option, if you don't care for the standard rubber hoses.

Phantom High Pressure Kevlar Double Braided Hoses


Phantom double braided high pressure hoses have an outer polyester braided cover that is laid over a woven Kevlar layer The Phantom double braided high pressure hose has a typical outside diameter that works better with hose boots and consoles. Every Phantom double braided high pressure hose is tested to 5000 psi and a rated burst strength of 22000 PSI. Fittings are made from quality chrome-plated brass. The typical high-pressure hose is a 7/16-inch male at the end that screws into the first stage HP port and a 7/16-inch female at the end that screws on to the SPG. Length is measured in inches, from end to end of hose, including the fittings and their threads.


Hoses for SCUBA - Dive Gear Express

Are you saying categorically, that there is no inner piece that can unscrew, as in the issue that created this thread?
Regards,
DanV