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Hybrid Pressure Safety

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Hybrid Pressure Safety

Unread postAuthor: Lentamentalisk » Fri Feb 20, 2009 1:57 am

OK, I am working on designing an extremely high "x" hybrid, and I was wondering whether a hydraulic ball valve would work at the same pressures with a gas. I know that hydraulic check valves don't work with gases, so I thought it would be good to check.
Here is the one specifically I am thinking about: 4715K44

Also, would sch 80 seamless, 2" steel pipe be with in its pressure rating at 3000psi?
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Last edited by Lentamentalisk on Fri Feb 20, 2009 2:32 am, edited 1 time in total.
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Re: Hydrolic ball valves

Unread postAuthor: starman » Fri Feb 20, 2009 2:09 am

Lentamentalisk wrote:OK, I am working on designing an extremely high "x" hybrid, and I was wondering whether a hydraulic ball valve would work at the same pressures with a gas. I know that hydraulic check valves don't work with gases, so I thought it would be good to check.
Here is the one specifically I am thinking about: 4715K44


The write-up says it will operate to 5000 psi of Working Steam Pressure. Since steam can be considered a gas, I imagine it would extend to other gases as well. The wildcard in there is the temp rating of only 212 degrees F. However, high hybrid temp spikes are very short duration so I doubt it will have a huge effect on the operation.

I don't know about the steel without looking it up...

Just how high X, would we be contemplating here??
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Last edited by starman on Fri Feb 20, 2009 2:15 am, edited 1 time in total.
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Unread postAuthor: Lentamentalisk » Fri Feb 20, 2009 2:15 am

W.S.P. (working steam pressure): Not rated

I am pretty sure that the numbers at 212 are for a liquid, given that at those pressures, it would still all be a liquid.
I found a better solution. I will just use a 3000psi check valve, and then a cheapo ball valve. 45105k74
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Unread postAuthor: starman » Fri Feb 20, 2009 2:20 am

Their description there are a little confusing but I think you're right.

Your McMaster number (45105k74) isn't computing back on their site.
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Unread postAuthor: Lentamentalisk » Fri Feb 20, 2009 2:22 am

oops, my bad handwriting... 46105K74

I am trying to find a handbook to pressure ratings of various pipes, but haven't been able to find anything. Any hints?

Edit:
ok, I found this: http://www.sorinc.com/usefulInfo_pipeSize.stm
which seems to say that I will need sch 160 in order to be rated past 3000psi at 2".
Poop. Thats gonna cost me...

edit: Forking hell!
18"x2" of sch 80 is $35
18"x2" of sch 160 is $120!
There is no way I am going to do that.

Well I was only going to use it at 2000psi, I just wanted that safety factor, with such high pressure pipes, so 2575psi rating should be good enough
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Re: Hydrolic ball valves

Unread postAuthor: Ragnarok » Fri Feb 20, 2009 3:31 am

I'll try doing one of my explanations on this, see if it's any clearer.

starman wrote:The write-up says it will operate to 5000 psi of Working Steam Pressure. The wildcard in there is the temp rating of only 212 degrees F.

It's good to 5000 psi of Working steam pressure, it's got to be able to take more than 212 F - because, 212 F is when the vapour pressure of water hits 1 atmosphere absolute pressure - in other words, when it's pressure is high enough to allow it to exist as a gas in at sea level. This is obviously short of 5000 psi, which would require dry steam - that is, above water's critical temperature of 705 F, at a minimum.

It's much like CO2 or Propane - where their vapour pressure changes with temperature, so does water's. It just happens that at RTP, CO2 and Propane have vapour pressures above atmospheric, water has a vapour pressure below atmospheric.
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Unread postAuthor: trigun » Fri Feb 20, 2009 5:47 pm

well 2" schedule 40 steel pipe has been used by dyi up to 20x i think more after he did more testing
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Unread postAuthor: POLAND_SPUD » Fri Feb 20, 2009 6:09 pm

what has happend to DYI? I haven't seen him for quite a long time
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Unread postAuthor: trigun » Fri Feb 20, 2009 6:10 pm

Well a few members actually know of what happened to dyi but dyi didnt want it to be discussed unless given his consent. So he is fine and well probally busy and just doesnt have the time.
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Unread postAuthor: FishBoy » Fri Feb 20, 2009 6:58 pm

personally, I would not use pvc. I would go with galvanized steel as trigun said. I used it for my hybrid (unposted) and it works quite well.
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Unread postAuthor: Lentamentalisk » Sat Feb 21, 2009 1:10 am

What the hell are you talking about? you are the first one to even mention the letters P, V, and C together in the same word, in this entire thread!
I am talking about sch 80 and 160 seamless steel! PVC would be suicide in a 20x mix.
I plan on being able to be not inside a bunker when firing this.

And galvanized? Do you realize that galvanized pipe is nearly 2x as expensive, and offers absolutely no benefit for a non-water carrying pipe?

Please read the thread before trying to be helpful
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Unread postAuthor: Fnord » Sat Feb 21, 2009 9:53 am

I would recommend finding a plumbing supply store. If they want considerably more for threaded sch80, I'd just buy it unthreaded, then take it to home depot and get somebody to thread it for you.

You probably won't find seamless so I'd try to find sch160 to compensate.
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Unread postAuthor: Lentamentalisk » Sat Feb 21, 2009 4:26 pm

Um...

Unthreaded: 7972K319 $88
Threaded: 5016T75 $64

I save $24 by having them thread a piece of 36" pipe for me beforehand, not even counting the cost of having Home Despot thread it for me. (I say 36" because McMasters doesn't sell too many sizes of unthreaded so I chose that for comparison.)

I can gaurentee that there are no plumbing supply places around here that carry pipe rated at 3000psi. I know the best one around, and they don't carry anything over 500. What I need is an industrial supply place, like McMasters.
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