Plumbing question.

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couv
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Plumbing question.

Sun Jul 16, 2017 5:14 pm

Other than cost, is there a reason not to use flex lines to connect frame mounted components such as the final after cooler to the water separator or the air filter to the PMV? I.e. would the vibration from the engine and compressor eventually cause problems? Any other issues to be concerned about using flex lines in that application?

TIA,

Couv
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tbone1004
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Re: Plumbing question.

Sun Jul 16, 2017 6:25 pm

no reason not to. Flex lines would handle vibration better since they wouldn't transmit. The cost of flex lines us huge compared to hard lines though and if you have a permanent or semi permanent system, I don't really see much of an advantage to flex lines

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antique diver
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Re: Plumbing question.

Sun Jul 16, 2017 7:22 pm

Hose is not necessarily higher in cost than tubing when you consider the cost of tubing fittings. There is a good source of good flexible 6000 psi rated hose for about $4.25 per foot plus ends, which typically cost about $5 each for common npt ends or JIC flared ends (preferred). They are made to any custom length you want and usually ship by next day. Check out hoses, tubing and related connections and a wide variety of HP fittings at www.augustindustries.com.
If you have questions about what you need contact me by email or on here on forum. Also you can reach August Industries at 972-245-7000 and ask for parts sales or ask for Casey. Here is a link to the hose and related ends page: http://www.augustindustries.com/shopdis ... ssure+Hose
Look at HOSE-3, END-34 and/or END-35. If you want the JIC ends (END-35) you may need some inexpensive JIC ends to mate up to any NPT pipe threads on your application.

If all that is confusing, you can send me photos of where you want what, and we can help you figure it out.

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couv
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Re: Plumbing question.

Mon Jul 17, 2017 8:19 am

Thanks guys. It's my neighbors compressor but I'm contributing to the build. I might have the correct size flex lines available already. I just did not want to plumb it up only to find out later that hard lines should have been installed in the first place.
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SurfLung
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Re: Plumbing question.

Mon Jul 17, 2017 10:30 am

Thanks Bill. I have another question, but its not about compressors...

Seeing the exotic multi-tank systems the Cousteau used, and that they were connected with metal tubing rather than a manifold, I have wondered if something like that could be done with flexible high pressure hoses?
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antique diver
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Re: Plumbing question.

Mon Jul 17, 2017 12:29 pm

SurfLung wrote:Thanks Bill. I have another question, but its not about compressors...

Seeing the exotic multi-tank systems the Cousteau used, and that they were connected with metal tubing rather than a manifold, I have wondered if something like that could be done with flexible high pressure hoses?


Yes. No reason that wouldn't be fine. They would have to be made to almost exact length or preferably a little longer to allow a "U" or pigtail (complete 360 loop) between cylinder fittings. They would have to fit in where there is no stress ( or very little) at the hose to fitting crimp area. Some earlier manifold setups with single set of tank bands relied on the manifold for some of the rigidity of the system, but your system with two band assemblies would be rigid.

I have been toying with building a very similar setup of small doubles with valves down and a rigid tube going up between the inverted cylinders to the SCUBA connection. It would be supported by attachment to the band bolts. My cylinders are about 5 - 5.5" and I was originally going to use a typical Sportsways manifold, but that spreads the cylinders out with a larger gap between them than I want. I have built a set of bands that will bring them very close together for a nice compact and streamlined rig. I haven't put the valve and "soft manifold" together yet, and I will probably use SS tubing and fittings because I have lots of that stuff, but no reason that I couldn't do it with hose, except the valves may be too close together to loop the hoses properly. We tend to forget that rigid manifolds just aren't the only way to go!

tbone1004
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Re: Plumbing question.

Mon Jul 17, 2017 5:29 pm

used to be plenty of pigtail cheater manifolds out there.
GUE also uses something similar to connect the tanks for their JJ and RB80 rebreathers. I believe Deep Sea Supply made a few custom valves and manifolds for similar projects
lola makes several commercially available options

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couv
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Re: Plumbing question.

Sat Jul 22, 2017 10:31 pm

Another question.

My friend has acquired a piston type hydraulic accumulator to convert into a filter stack. This particular one has a different end cap setup than I'm used to seeing. Instead of end caps which screw into or onto the barrel, it has large snap rings to prevent the end caps from blowing out. Has anyone seen this type of accumulator before? Any reason to believe they are not safe?

Sorry I don't know the new procedure for attaching pictures.....I copied this post and pasted the pictures at SB-the links are below.

TIA

Couv

https://www.scubaboard.com/community/at ... pg.419369/

https://www.scubaboard.com/community/at ... pg.419370/
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captain
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Re: Plumbing question.

Sun Jul 23, 2017 11:17 am

What was the pressure of the hydraulic system they are used on. Unlike air if they fail in a hydraulic system not much happens except for some oil on the ground. Most hydraulic parts and pieces are rated either 3000 or 5000 psi.
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couv
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Re: Plumbing question.

Sun Jul 23, 2017 2:00 pm

captain wrote:What was the pressure of the hydraulic system they are used on. Unlike air if they fail in a hydraulic system not much happens except for some oil on the ground. Most hydraulic parts and pieces are rated either 3000 or 5000 psi.


Hi Tom,

It's supposedly from a 3000 psi system. You've pointed out my exact concern. Like a scuba tank being tested with water, not too much drama if it fails; but a failure when filled with gas is a different matter. Having said that, this accumulator is a hydro-pneumatic unit where one side is filled with a gas pre-charge and the other has hydraulic fluid. I've seen lots of aircraft with hydro-pneumatic accumulators before, but they've always had screw-on end caps.

I'm hoping someone here or on SB can confirm this type of accumulator is safe for high pressure pneumatic service as the only pressure rating indication on it is a sticker.

Thanks,

Couv
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antique diver
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Re: Plumbing question.

Sun Jul 23, 2017 3:02 pm

First, if it is aluminum I just flat would not use it no matter what the pressure rating.

If it is steel I think those are 3000 psi rated. However, I am 99% certain that the end plugs are aluminum, and must be carefully examined for corrosion and cracks. If these have been wet, the electrolysis between the steel and Aluminum can damage the integrity of the plugs.

Your concerns about the expansion of escaping air are certainly valid, and I have always been troubled about ththose retainer rings (no I did not accidently misspell "those"... I was stuttering at the thought of them), although these surplus accumulators were in common use in the 60's and 70's. The only accident with these exact units that I personally know of was at Lake Whitney, Texas, in the 70's. One of the ends blew out, sending a missile up through the roof. I don't know what parts hit the owner (I don't think the tube split), but he sustained a badly broken arm and a case or ringing ears. Made a mess in the shop (and maybe in his shorts). He felt lucky to be alive. If I recall he quit pumping air.

The cause could have been a failure to fully seat the retaining ring into its groove... or it could have been a failure of actual ring, or of the metal groove. I doubt that was ever determined for sure, but I believe it could easily have been user error.

Anyway, they scare me. :shock:

I think these may have been made as lightweight as possible for use in aircraft, and maybe never intended for such long term use. I know the guy that built that compressor system, and will try to find out more from him. Of course there was legal action over the event, and he may still be wanting to just cover his backside and not talk about it. I'll post it here if I can obtain any real facts from him.

New filter towers are expensive, but so are medical bills, building repairs, and of course funerals have gotten very expensive too. Just sayin'....

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antique diver
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Re: Plumbing question.

Tue Jul 25, 2017 7:45 pm

Update on Lake Whitney accident:
I contacted the friend that owned the company that put the compressor and "filtration" accumulator together in the early 70's. I had heard some erroneous info about the accumulator that blew apart, and want to set that straight. It was a similar item but instead of the ring type retainer it was the type with a screw on aluminum cap. The cap blew off with same results as I previously related, with one important difference. The operator had just repacked his filter material and capped the cylinder, and upon reaching full pressure and compressor shutoff he was able to hear an air leak from top cap. The fellow took a large wrench to the cap and attempted to tighten it further while still under full pressure! That's when the big noise occurred, the ground shook and bones broke. So there's a lesson in monkeying with high pressure fittings and connectors while under pressure. :shock:

After the lawsuit smoke cleared and the builder had paid the medical bills, he decided to scrap the remaining large number of hydraulic accumulators that he had bought as military surplus for about $5 each, even though the wrench monkey was the probable main cause of that specific incident.

Here's the thing you might hear in court after such an incident.... "Was that item designed to be used in that manner?"

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couv
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Re: Plumbing question.

Tue Jul 25, 2017 9:29 pm

Thanks for the updates Antique Diver. The barrel and end caps look new and free of corrosion. I don't know the type of material but will look into it.
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