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pre engineered silencers...DUH!

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Unread postAuthor: POLAND_SPUD » Thu May 07, 2009 12:21 am

@ rag
with 650 ccm chamber volume and 300 psi it must have been a real PITA to pump it with a stirrup pump... :wink:

high pressure guns started to spread once firdge compressors appeared... lol I wouldn't have the patience to use a stirrup pump to pump 650 ccm
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Unread postAuthor: Ragnarok » Thu May 07, 2009 12:32 am

POLAND_SPUD wrote:it must have been a real PITA to pump it with a stirrup pump

Actually, it's not bad in the slightest. The pump has a pretty large stroke (slightly over 20mm bore), so it normally reaches pressure well inside a minute, even with leisurely paced pumping.

If you really want to contemplate madness, I'm considering pressurizing the air supply for the semi-auto 500 psi HEAL 2 with a manual pump... good thing that I'm in good fitness.
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Unread postAuthor: POLAND_SPUD » Thu May 07, 2009 12:35 am

lol I suggest switching to a fridge compressor...
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Unread postAuthor: Ragnarok » Thu May 07, 2009 12:43 am

POLAND_SPUD wrote:lol I suggest switching to a fridge compressor...

Nah, I'd spend forever if I had a fridge compressor, singular.

Also, the reason I'm contemplating it is because I can't find fridge compressors particularly easily.
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Unread postAuthor: jook13 » Thu May 07, 2009 12:46 am

My best friend works for the city. Twice a year our city has a "free dump day" which means anybody in the city can take all the trash in for free. This includes appliances like fridges. After all is said and done I have free roam of the fridges and the compressors on them. :D :D
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Unread postAuthor: Moonbogg » Thu May 07, 2009 1:58 am

Perhaps the mufflers would work with a 2" x 12" chambered hybrid.
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Unread postAuthor: jackssmirkingrevenge » Thu May 07, 2009 2:08 am

Moonbogg wrote:Perhaps the mufflers would work with a 2" x 12" chambered hybrid.


Not the ones you linked to though, there's no place for the projectile to pass through.
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Unread postAuthor: Moonbogg » Thu May 07, 2009 4:47 am

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Unread postAuthor: SubsonicSpud » Thu May 07, 2009 5:48 am

Moonbogg wrote:http://www.anver.com/document/vacuum%20components/vacuum%20mufflers/flow-through_silencers.htm


I very much doubt they would have much effect on an air powered weapon, mainly to due to their lack of volume. The design also seems to be a muffler style perforated pipe with wadding, not very effective at reducing an air gun report. You really need to have the seperated baffles after the barrel to greatly reduce the report of a air gun

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Unread postAuthor: LeMaudit » Thu May 07, 2009 7:15 am

Just thinking I have used for my basement renovation this product:
http://www.roxul.com/sw47802.asp

My application was basically in the walls and ceiling (it do wonders!), but I remember a product demo at the Home Depot where there was a little 2' wood box with a loud radio inside. The box was padded with this stuff. When the box was closed, you could barely hear the radio.

I wonder if this could make a good candidate as silencer filling stuff ?
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Unread postAuthor: SubsonicSpud » Thu May 07, 2009 7:45 am

The idea of silencing a weapon is to contain the expanding gases. Silencing a firearms is not like trying to soundproof a box or cavity where you are trying to absorb small pressure waves. In a firearm there is a large release of gas out of the barrel this needs to be contained and released slowly out of the silencer. This can only be achieved by providing a large volume chamber for the gas to expand in and also to make it difficult for the expanding gas to escape into the atmosphere with the use of baffles and wipes at the exit of the silencer.

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Unread postAuthor: inonickname » Thu May 07, 2009 7:56 am

Yep, ideally the dead space after the round (i.e silencer/shroud) should be calculated and working pressures be taken into account. Ideally the gasses should expand to atmospheric pressure, no lower or higher.

If it is higher you will still have the gasses exhausting rapidly, and if too low a vacuum may form, dropping power and making sound as gasses rush back in the chamber.

While having such a large expansion chamber is out of practicality for most launchers. Cooling combustion gasses also has a massive effect. Baffles also help.

On topic; they don't seem suitable. While these may be different pneumatic silencers normally just aim to slowly diffuse gasses.
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Unread postAuthor: LeMaudit » Thu May 07, 2009 8:03 am

I knew if was something like a maze of intricate chambers inside a silencer, but somehow I thought there was also some filling stuff.
Oh well, another thing to learn. I'll explore the forum. If you have at hand some good links about DIY silencers please share.
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Unread postAuthor: LeMaudit » Thu May 07, 2009 8:14 am

Ideally the gasses should expand to atmospheric pressure, no lower or higher.


If I understand you well, does that mean to silence my PCP cartridge with their 1 cubic inch air chamber compressed at 400 psi, I would need something like 28 inch3 as a silencer? (supposing my math is correct)

That would be something like a 2 1/2" diameter cylinder, 6" long. Manageable... and surely killer look :-D
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Unread postAuthor: SubsonicSpud » Thu May 07, 2009 8:23 am

LeMaudit wrote:I knew if was something like a maze of intricate chambers inside a silencer, but somehow I thought there was also some filling stuff.
Oh well, another thing to learn. I'll explore the forum. If you have at hand some good links about DIY silencers please share.


Having filling inside of a silencer is really only effective in combustion firearms as it provides more surface area to help cool the hot gases. The cooling of the gases reduces the amount they expand and reduces the volume needed for the silencer. As there is no heat to lose from the gases of an air gun there is no real use for wadding. The only benefit would be to reduce the amount of resonation inside the silencer chamber, but it would not have a great reduction on the noise output.

Edit:
As for you're second post, you may not need something that big. It just depends how quiet you want it. Here is what I used on a copper Coax gun of 10mm bore with a much larger chamber than you have described

Image

It is about 22cm long and 3cm in diameter and uses four baffles, two with duct tape wipes and was very efective at lower pressures of around 180-200psi, above that it lost it's effect

Image

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Last edited by SubsonicSpud on Thu May 07, 2009 8:51 am, edited 2 times in total.
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