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"Maco2" high pressure hand pump (250 Bar!)

popgun pete

Well-Known Member
Jul 30, 2008
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590
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Australia
Some time ago I was looking at the "Maco2" expellable gas speargun web-site, more out of curiosity than anything else. The "Maco2" guns use either carbon dioxide or compressed air, according to the information on the web-site, which is stored in pre-pressurised cylinders or tanks that attach directly to the gun. The layout of the "Maco2" gun is similar to the fifties "Pelletier" spearguns which actually inspired the creation of this modern version of the guns.

I was surprised to see in the "Maco2" May 2009 catalogue (pdf file from the web-site) the mention of a 250 Bar hand pump, in fact there is even a photo of the pump showing its pressure gauge calibrated to 250 Bar! Does anyone know how this pump works as I cannot believe that a simple hand pump could ever reach that sort pressure, or even half that amount. Plus to compress from ambient and transfer a volume of air at that high pressure to fill a tank theoretically should take an enormous number of pump strokes, it would have to be in the thousands. Adiabatic heating makes compressed gas get very hot, even pumping to 40 Bar with a pneumatic speargun hand pump heats up the lower body of the pump, so you can imagine what over six times that pressure would produce, even if you could push the pump handle down at anything like that sort of pressure. As expellable gas guns consume a lot of gas per shot then hand pumping to pressurise the cylinders or tanks seems to be a crazy idea, but maybe I am missing something.

The 250 Bar hand pump is listed at 285 Euro, maybe it is a bit more than a simple hand pump, it would definitely need to be at that price!

I just revisited the web-site, the pdf catalogue seems to have disappeared, now there is a "shop" menu. You can see the high pressure pump here: http://www.maco2spearguns.com/en/shop.php?cat=Miscellaneous&ref=75

The price of the high pressure pump is now 300 Euro!
 
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radlimus

New Member
Oct 21, 2009
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Stuttgart
These pumps has a very small diameter.
There are existing hand and foot pumps for filling air shooting chambers (300 Bar).

In the history were diving bottles filled by hand compressors to 180 Bar, pumping many hours and then diving 30 minutes:blackeye.
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,035
590
153
Australia
Thanks for the information, could be the same pump as very similar configuration in both cases. The high cost would seem to indicate an elaborate construction, not just a simple tube with a plunger like you get with a pneumatic speargun pump.

I searched on FX Airguns (Sweden) and found this review: http://www.targetsportsmagazine.com/features/view/10220/product-test-fx-pumps/. Their stirrup pump is a multi-stage device, so that explains the high pressure pumping capability.
 
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foxfish

Silver Smoker
Staff member
Team Leader
Dec 31, 2005
12,932
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Guernsey, Channel Islands
I know I have been down this avenue before Pete but it just seems that our underwater guns are out of the ark compared to the amazing pre charged air riffle sytems available.
The barrel above the air chamber concept seems such a better format for a spear gun design, there have been several members who have suggested such a gun will be manufactured but I am still waiting for my dream machine!
I am not suggesting a stored air & dumping system just that a under-barrel air chamber would make aiming the gun far more natural.
 

Old Man Dave

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Feb 19, 2005
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Guernsey, Channel Islands, UK.
I'm working on it again. Currently considering remaking the handle/trigger block in billet marine grade ali (HE30) and using the exsisting barrel, piston, trigger etc from a standard pnemo gun. Air resevoir will be a custom made 25mm dia ali tube construction. This is a simple scematic with threads, seals/o rings omitted. Drawn on CAD, to scale, to check out proportions. Main prob looks to be bouyancy/displacement/weight. Looking promising though. Finished gun CAD is a scale drawing of a 90cm - approx.

Dave.
 

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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,035
590
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Australia
Just to complete this thread I can now say that I have found a schematic of the innards of this high pressure pump. It is a series of concentric tubes sliding within each other with the central tube having a very narrow bore anchored at the bottom, with a second tube sliding over it anchored to the tee handle (essentially the pump handle "rod") which in turn slides within an outer tube connected to the base that forms the outer body of the pump. Each end of the tubes has a bulkhead, one of which slides over and/or within one of the other tubes. The smallest, innermost bore is pumped by a narrow rod connected piston concentric with the second tube and which is also attached to the tee handle. So you have variable volume air spaces on each side (top and bottom) of the sliding bulkheads and the small inner piston as the tubes move up and down with respect to each other and transfer air across to the smallest bore inner tube, compressing it in the process. There appears to be a water collection point at the pump base (to remove condensate).

No wonder this "FX Airguns" pump is very expensive because it is full of "O" rings providing both stationary and dynamic seals at the various bulkhead and tube travel locations. I have also discovered that it is for pumping up relatively small volume air tanks in the air rifles (PCP types), around 200 cc to 400 cc of internal capacity. The hand pumps are said to get hot after 5 minutes of hard pumping due to adiabatic heating and need a rest to cool down and not over cook the "O" ring seals. It would be a big job pumping up a pneumatic speargun from scratch with one as the former contain much larger air volumes inside the gun's reservoir than that found in an air rifle. If you are wondering why such a pump is of interest to me then consider that my "Black Sea" hydropneumatic speargun uses 100 Bar in its internal reservoir, it can be filled from a scuba tank using an adaptor, but a manual pump to top it up would be useful rather than having to keep a scuba tank on hand. The gun does not lose air when shooting, however pneumatic guns depressurise eventually, although it can be over a very long time period, so may not be a problem. The drawback is the price of the pump, not surprisingly it is around the price of a gun, it has as many if not more internal parts.

As for your "barrel on top" pneumatic speargun, might I suggest that you anchor the pressure bulkheads with an inner metal tube or rod to save on screw threading the front and rear bulkheads of the air reservoir tank into the ends of the tank itself, it will save a lot of weight and just requires perforations in the inner tube's wall to pass air into the tank (if you use a rod then one end has to be bored out and radially drilled for an air path). It will be like the inner barrel of a standard pneumatic, just not as large in diameter, plus it gives you somewhere to locate the inlet valve body. Your main problem is anchoring the upper barrel to the gun so that it takes the force of loading the gun without bending with respect to its connection point. You can take as a guide the old fire extinguisher based carbon dioxide guns of the fifties, they had this barrel on top layout, but their spear loading effort was zero. They disappeared in favour of concentric barrel carbon dioxide guns, something for you to think about!
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,035
590
153
Australia
The SMACO high pressure hand pump from China is best included here as it may not attract much attention "buried" in the speargun oil thread https://forums.deeperblue.com/threads/oil-for-use-in-pneumatic-spearguns.114312/page-3


These pumps can pump to 3000 psi for filling "Spare Air" type cylinders, however they should be good with an adaptor for filling high pressure pneumatic guns, i.e. those using more than 600 psi. The hand pump has an in-built pressure gauge so that you know how much air has been pumped into the gun.

These Chinese clone hand pumps cost about 100 bucks each, including shipping, as a large number of people are selling them on eBay and there is a lot of competition among the various sellers who offer them separately or as part of an underwater breathing kit.

https://www.ebay.com.au/itm/SMACO-Oxygen-Cylinder-Scuba-Diving-Breathe-Equipment-Air-Tank-Oxygen-Kit-Set-AU/383062858364?hash=item5930535a7c:g:ntsAAOSwYeZdKY~q

There are lots of glossy photos advertising the units, but just why this user would need one is unclear.
 
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