Expanding plenum volume

[elaerico]

Hi. I'm new in the forum. I'm from Argentina, and I own a SPA P15, and I want to increase it plenum volume. Currently has 12cc, and I want 30 fpe. I have a lathe, so I can manufacture the plenum extension. I was thinking in making an extension of the tube, where it connects with the valve. But I have some questions about sizing. I never before worked with pieces who holds this much pressure. I used an online calculator for strain, and came up with using 1045 steel, and a cylinder with walls of 4mm,it will hold up to 480 bar, three times the working pressure.
Can you give me an advice in the manufacturing, calculing, or something else?
Thanks a lot!

First, welcome to the mad house my friend.   

Truthfully I think you may be better off looking in the machine shop section of the forum...but I myself am unfamiliar with the model you are speaking of, maybe if I find anything out about it I will offer some conjecture about methods and implementation, but I definitely need more info. You are on the right track with the 3 to 1 safety margin though.you also may want to consider what else needs done to prep for these pressures.  What kind of pressure is it currently rated for? ( Meaning factory recommended operating pressure)

The current deposit rating pressure is 3600 psi, but in the plenum should be half of that.

[antithesis]

Hi. I'm new in the forum. I'm from Argentina, and I own a SPA P15, and I want to increase it plenum volume. Currently has 12cc, and I want 30 fpe. I have a lathe, so I can manufacture the plenum extension. I was thinking in making an extension of the tube, where it connects with the valve. But I have some questions about sizing. I never before worked with pieces who holds this much pressure. I used an online calculator for strain, and came up with using 1045 steel, and a cylinder with walls of 4mm,it will hold up to 480 bar, three times the working pressure.
Can you give me an advice in the manufacturing, calculing, or something else?
Thanks a lot!

First, welcome to the mad house my friend.   

Truthfully I think you may be better off looking in the machine shop section of the forum...but I myself am unfamiliar with the model you are speaking of, maybe if I find anything out about it I will offer some conjecture about methods and implementation, but I definitely need more info. You are on the right track with the 3 to 1 safety margin though.you also may want to consider what else needs done to prep for these pressures.  What kind of pressure is it currently rated for? ( Meaning factory recommended operating pressure)

The current deposit rating pressure is 3600 psi, but in the plenum should be half of that.

Well I looked at it a little and while I don't know what the internals look like, I believe I DID see a drop in reg that runs higher pressure.....this bullpup design doesn't look like it will have any easy way to expand the plenum volume so maybe a little bump in pressure may be a better route.... but then where there is a will there's a way.  ..if the plenum volume truly is only 12cc then 30 fpe is gonna be a tough number to hit efficiently without some serious modding. 

If it was me and I were *(&^ bent on getting more available air, I would consider checking to see if you can find space for something external like a second tube piped into the primary, like I plan on doing with my gauntlet. The gauntlet has several  ways to do this, by either using a longer main tube or by making a channel in the stock to hold a secondary that feeds the main. There is plenty of room in that gun for more tube.

[elaerico]

Hi. I'm new in the forum. I'm from Argentina, and I own a SPA P15, and I want to increase it plenum volume. Currently has 12cc, and I want 30 fpe. I have a lathe, so I can manufacture the plenum extension. I was thinking in making an extension of the tube, where it connects with the valve. But I have some questions about sizing. I never before worked with pieces who holds this much pressure. I used an online calculator for strain, and came up with using 1045 steel, and a cylinder with walls of 4mm,it will hold up to 480 bar, three times the working pressure.
Can you give me an advice in the manufacturing, calculing, or something else?
Thanks a lot!

First, welcome to the mad house my friend.   

Truthfully I think you may be better off looking in the machine shop section of the forum...but I myself am unfamiliar with the model you are speaking of, maybe if I find anything out about it I will offer some conjecture about methods and implementation, but I definitely need more info. You are on the right track with the 3 to 1 safety margin though.you also may want to consider what else needs done to prep for these pressures.  What kind of pressure is it currently rated for? ( Meaning factory recommended operating pressure)

The current deposit rating pressure is 3600 psi, but in the plenum should be half of that.

Well I looked at it a little and while I don't know what the internals look like, I believe I DID see a drop in reg that runs higher pressure.....this bullpup design doesn't look like it will have any easy way to expand the plenum volume so maybe a little bump in pressure may be a better route.... but then where there is a will there's a way

I attached the picture of the piece I want to make. The black one is the original, and will be replaced with the shiny one. Sometimes one picture is better than a hundred word.

[antithesis]

Hi. I'm new in the forum. I'm from Argentina, and I own a SPA P15, and I want to increase it plenum volume. Currently has 12cc, and I want 30 fpe. I have a lathe, so I can manufacture the plenum extension. I was thinking in making an extension of the tube, where it connects with the valve. But I have some questions about sizing. I never before worked with pieces who holds this much pressure. I used an online calculator for strain, and came up with using 1045 steel, and a cylinder with walls of 4mm,it will hold up to 480 bar, three times the working pressure.
Can you give me an advice in the manufacturing, calculing, or something else?
Thanks a lot!

First, welcome to the mad house my friend.   

Truthfully I think you may be better off looking in the machine shop section of the forum...but I myself am unfamiliar with the model you are speaking of, maybe if I find anything out about it I will offer some conjecture about methods and implementation, but I definitely need more info. You are on the right track with the 3 to 1 safety margin though.you also may want to consider what else needs done to prep for these pressures.  What kind of pressure is it currently rated for? ( Meaning factory recommended operating pressure)

The current deposit rating pressure is 3600 psi, but in the plenum should be half of that.

Well I looked at it a little and while I don't know what the internals look like, I believe I DID see a drop in reg that runs higher pressure.....this bullpup design doesn't look like it will have any easy way to expand the plenum volume so maybe a little bump in pressure may be a better route.... but then where there is a will there's a way

I attached the picture of the piece I want to make. The black one is the original, and will be replaced with the shiny one. Sometimes one picture is better than a hundred word.

Oh yeah that clears it up a little.....so you are sure this will fit where you need it? ( I cant tell where it is supposed to actually connect)....and it's already made?

Jeez you are further along than I had thought. If no other changes were made besides it being bigger and you made all the necessary calculations I cautiously say go for it!....I have no idea how the gun is put together, is that piece inside the tube?

[elaerico]

No, that piece is outside the tube. Between the tube and the valve housing. I think that's better becouse It won't loose compressed air capacity. In fact, it will increase it.

[antithesis]

No, that piece is outside the tube. Between the tube and the valve housing. I think that's better becouse It won't loose compressed air capacity. In fact, it will increase it.

If there is no major alterations in how it's attached (threads?), Or operating pressure, as long as the numbers line up it looks solid to me. ..I still have to get a better look at one of these to better understand the construction

EDIT: I still don't know exactly how or where, but I see Huma selling something similar, may be worth looking at just to get a better idea of how your piece compares

[elaerico]

Huma sells an extension, but that extension goes inside of the main tube, taking out air volume from the unregulated size.