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Pneumatic vacuum cup with valves

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Zahar

Well-Known Member
Jun 3, 2014
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A conceptual pneumatic vacuum mug with valves must provide sufficient firing force when the pneumatic vacuum cuff fails by ejecting leaking water into the barrel through an emergency valve! The first valve is necessary to reduce the water pressure on the pneumatic vacuum cuff during the introduction of the harpoon into the gun when loading!
 

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Aha, using o-rings as valves covering transverse holes in the muzzle?
Pink is the vacuum seal, green is the shock absorber, right?

But if these are the UBL (Salvimar, Pelengas) type vacuum cuffs I think they open by themselves when you load, so no need for a valve.



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The piston closes the hole in the shock absorber like a faucet! When the harpoon is inserted between the vacuum cuff and the shock absorber, until the moment of piston shift, a water pressure is created which compresses the vacuum cuff and creates friction and wear of the cuff when loading! To avoid this, you can make cuts on the shank of the harpoon or put the valve 1
 
I am wondering if valves are really needed when using UBL type vacuum seals?
The reason I am not convinced that they are is that every time I load either a UBL muzzled gun or a Predathor one, when I insert the shaft a small squirt of air and bubbles come out the front of the muzzle. I see that as proof that the cuff opens to let the water out as the shaft end travels from the cuff to the piston forcing the water out.
Perhaps at the very rear end of the muzzle, when the shaft tail is inside the shock absorber there could be more of an issue - I guess it depends on whether you feel the gap between the shaft tail and the shock absorber is so tiny that the water can't escape fast enough? But then again, the only other place it can go is behind the piston seals and those have 18-20bar of pressure acting upon them in most guns. I am not smart enough to figure out whether inserting a shaft in normal operations create more force on the water than the air does on the piston seals.

Now, if were were talking about the shot itself - especially on a deep dive when there is more compression on the cuff - then you could have a point. But then again, if the "extra" water was let out by the cuff expanding (during the loading) and there is no leak, then there shouldn't be "too much" water trapped in the barrel during the shot, either.

I am not sure I am right, I am just basing this on what I see when I load my guns.
 
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In a pneumatic vacuum gun there should not be a lot of water in the barrel but it is enough to lubricate the O-rings of the piston when fired! How to achieve this? Valve chamber 1. Without valve 1, when entering the harpoon, almost all the water between the piston and the vacuum cuff is removed and the shot is fired with dry friction of the piston O-RINGS!
 
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In a pneumatic vacuum gun there should not be a lot of water in the barrel but it is enough to lubricate the O-rings of the piston when fired! How to achieve this? Valve chamber 1. Without valve 1, when entering the harpoon, almost all the water between the piston and the vacuum cuff is removed and the shot is fired with dry friction of the piston O-RINGS!

Sorry, I still fail to see any operational difference between your idea and the expanding cuff design from UBL, maybe I am just not getting it;-).
Your o-ring valve will expand letting out the excess water when loading , but I think that's exactly how UBL/Pelengas/Salvi vacuum cuffs work, too? I can't picture how your design lets less water out - I think there would be the same amount of water left in the muzzle with both designs?

We are loading on the surface, not at depth, so each design should have an equally easy time opening as a valve, more or less. If so, then I would rather not have the external o-ring valves as it is one more thing that can leak. And for sure, if you shoot a vaccum gun which has water leaking into the barrel, then you are looking for A). an extremely throttled, low powered shot or worse B). water being forced behind the piston.

Don't get me wrong, I like the idea of using o-rings as a one way valve, I just still don't understand why it is needed.
That said, I think possibly with a muzzle that is using regular o-rings - and ideally should be loaded with the gun upside down above the surface (like a Tomba design) your o-ring valve could be an option. @tromic - any thoughts on this? And @popgun pete, what am I missing?
 
Charging a pneumatic vacuum gun without water, you reduce the life of the O-rings of the piston and increase the sound force of the piston strike when fired! Valve 1 makes it possible not to reduce the amount of water in the barrel, but, on the contrary, to increase it to the optimum amount for lubricating the O-rings of the piston when fired and the water is involved in damping the piston! But since you charge a pneumatic vacuum gun in the air without water, then you do not need valve 1! Valve 2 is enough for emergency discharge of water from the barrel when the pneumatic vacuum cuff is torn!
 
Gecko is right, the vacuum cuffs used in the modern pneumovacuum guns work like a one-way valve, the water cannot get in, but excess water blows out. This always happens when the spear tail is inserted underwater as water already in the muzzle opening is displaced leaving only that in the accommodation space with the spear tail in place. The first gun to use this concept in volume production guns was the "Taimen". The "Taimen" gun commenced production in the year 2000.
НОВАЯ ВТУЛКА Taimen 2 part hub cocked.jpg
 
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This design does not allow to dispense the amount of water involved in the lubrication of the O-rings of the piston and depreciation! But if it suits you well!

My idea is already 3 years old and maybe she pushed someone to the right decision! I would be glad! But no one has put the emergency valve! The idea was developed under the gun Pelengas with pneumatic vacuum muzzle!
 

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