Using aluminum for pump tube?

Using aluminum for pump tube?

Joined: March 1st, 2002, 12:22 am

December 1st, 2011, 5:09 pm #1


Oh ,say replicating a 1377 pump tube.

The pros are easy, its cheap, lightweigth and easy to work (hehehe even for me : ) )

Or is ti gonna be a multistroke pneumatic pipe bomb after 6 strokes?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
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Joined: November 28th, 2002, 6:26 pm

December 1st, 2011, 5:16 pm #2

...in the valve rather than the pump tube, so long as the valve is sound I don't think there's even the possibility of a significant explosion risk. However, given aluminum's relative softness and tendency to gall, more attention would need to be given to issues like adequate support of the linkage pins, piston lubrication, etc.

But given that brass can be made to work so well, I can't believe aluminum can't.

Steve
Last edited by pneuguy on December 1st, 2011, 5:17 pm, edited 1 time in total.
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Joined: September 23rd, 2002, 6:16 pm

December 1st, 2011, 5:36 pm #3

as the tube contains slightly higher pressure than the valve at the end of the pump stroke. So possibly a pressure ring would appear in a band determined by the valve seal oring and the sealing of the pump cup.

Walter....
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Joined: April 28th, 2010, 12:23 am

December 1st, 2011, 5:51 pm #4

Oh ,say replicating a 1377 pump tube.

The pros are easy, its cheap, lightweigth and easy to work (hehehe even for me : ) )

Or is ti gonna be a multistroke pneumatic pipe bomb after 6 strokes?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
laughed out loud dan thx
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Joined: April 28th, 2010, 12:23 am

December 1st, 2011, 5:53 pm #5

please photoshop a picture to explain the aftermath of the msp pipe bomb!
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Joined: March 1st, 2002, 12:22 am

December 1st, 2011, 6:12 pm #6

but I could see it splititng the tube

dr_subsonic's pneumatic research lab

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Joined: March 1st, 2002, 12:22 am

December 1st, 2011, 6:13 pm #7

as the tube contains slightly higher pressure than the valve at the end of the pump stroke. So possibly a pressure ring would appear in a band determined by the valve seal oring and the sealing of the pump cup.

Walter....
Thicker tube wall might stop that?

dr_subsonic's pneumatic research lab

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Joined: September 23rd, 2002, 6:16 pm

December 1st, 2011, 6:31 pm #8

could increase wall where needed with say a steel ring
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lhd
Joined: November 22nd, 2002, 10:41 pm

December 1st, 2011, 6:47 pm #9

Oh ,say replicating a 1377 pump tube.

The pros are easy, its cheap, lightweigth and easy to work (hehehe even for me : ) )

Or is ti gonna be a multistroke pneumatic pipe bomb after 6 strokes?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
Unlike steel, which normally will not become permanently stressed at load levels significantly below the threshold where some stretching begins to show up, even with many, many repetitions of the stress, aluminum has no such threshold, and can become fatigued by such repeated stress, even at levels lower than the point where permanent deformation would have occurred in virgin material.

Some common aluminum alloys, such as 6061 are more prone to this situation than say ... 7075, but the issue needs to be taken into account if many (thousands) of cycles that might approach the listed tensile limits are anticipated.

The T6 spec is a heat treat condition that gives much more strength due to an artificial aging effect. Part of this treatment is a soak at the quite low temp of around 325 degrees. I'm not expert at this, but suspect exposure to much higher temps might negatively affect the heat treat rating.

Not to say don't use aluminum, but just to say do the research and testing first.
Last edited by lhd on December 1st, 2011, 6:50 pm, edited 1 time in total.
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Joined: December 4th, 2005, 4:26 am

December 2nd, 2011, 12:07 am #10

Oh ,say replicating a 1377 pump tube.

The pros are easy, its cheap, lightweigth and easy to work (hehehe even for me : ) )

Or is ti gonna be a multistroke pneumatic pipe bomb after 6 strokes?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
It is possible to use aluminum for a pressure vessel, However, the big question that comes to my mind is Why? Steel is a much better choice for a pump tube. With brass or aluminum piston there isn't a problem with galling and if the steel is blued or plated corrosion isn't a problem. I and building a 2289 from scratch with a steel pump tube and brass valve and piston, in my opinion the best materials for the job.
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