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Question About Pump Volumes

Looking to replace my rf20's pump

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#1 snakerbot

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Posted 30 August 2009 - 09:28 PM

I want to replace my rf20 pump with one that doesn't suck so much, but I haven't been able to find much information about pump volumes. Are there any easily available guns that have pumps with equal or greater volume than the rf20 pump? I would imagine that the titan has a bigger pump, but I couldn't say for sure. I also think the berzerker/big blast might have larger pumps, but I can't really tell.

Thanks in advance.
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#2 Icespartan 1114

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Posted 30 August 2009 - 09:54 PM

I have seen a view people replace Rf20's pumps with a un-plugged titan pump. Works great.
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#3 Vinnie D

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Posted 31 August 2009 - 04:01 AM

You could always try a mini bike pump, just remember to be careful with it. I've had some success with a dual action mini pump on a big blast. I'd suggest looking into things non nerf. Most any bike pump will have more volume than a Nerf pump, meaning fewer pumps, and some have the double action meaning it pumps on both the in and out stroke resulting in half the pumps needed. Just don't get carried away with it or things explode.
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#4 snakerbot

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Posted 31 August 2009 - 10:34 AM

Thanks for the advice, and I have another question. I plan to integrate a few hornet tanks connected to a homemade smdtg trigger. (Think marvelous salvo) If I used a bike pump, would it be possible to overpump in this case? Basically, if I keep pumping the gun, would the release valve in the rf20 bladder activate before anything in the marvelous salvo explodes. My understanding is that the extra air would take the path of least resistance into the rf20 bladder and through the overpressure release valve. I'm trying to make it so I could pump the gun mid-battle after firing a number of shots, but without knowing exactly how many pumps to put into it and without worrying about anything exploding or breaking.
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#5 imaseoulman

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Posted 01 September 2009 - 05:15 PM

The RF20 pump isn't that bad. The MagStrike pump is a little better, and the BigSalvo pump is also pretty good. The Titan pump has the highest output, but it's a little awkward and harder to pump to higher pressures, due to its massive diameter (40 PSI over two square inches is eighty pounds of force, so that last pump can get pretty tough if you want higher pressures). My favorite pumps are the MagStrike and BigSalvo pumps, I also like the Lightning Blitz pumps for something more compact, but efficient.

The pumps on Big Blasts and Berserkers are tiny, the stroke is three-four inches, if that.

For your integration, if you leave the pressure relief valve in place and choose not to band the bladder, the relief valve will kick in long before the BS tanks have any problems. BS tanks can handle a higher pressure than most NERF air tanks (I take mine to 60 PSI frequently). The pressure in the bladder and the tanks will be at equal pressure while pumping. If you want different pressures you'll need some sort of valve (ball valve, toggle valve, etc.) to allow air to be pumped into only one or the other.

You seem to understand this pretty well, but your phrase "path of least resistance" doesn't quite apply in this case. The pressure you apply via the pump will be felt equally and undiminished throughout the entire system. This means that if your bike pump (assuming you use that) reads forty psig, then everything that holds the air (tubing, tanks, bladders, valves, etc.) have forty pounds of force per square inch exerted on them. I hope that was more helpful than confusing.

If you're interested in a flow path/schematic for your integrating with the necessary check valves, etc. labeled, let me know and I'd be happy to create one for you.
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#6 snakerbot

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Posted 01 September 2009 - 08:09 PM

Thanks for the help imaseoulman. My diagram has the check valves after the point where the tubing from the pump splits, but before the rf20 bladder and smdtg trigger. That way firing one of the guns (and thus lowering the pressure in that tank) does not cause the air from the other tank to flow backwards and equalize everything again.

Another thing, though. The rf20 bladder holds air at pretty low pressure, right? Quite a bit lower than would normally be in hornet tanks? This would decrease the range from the hornet tanks, but expanding them could raise the range to compensate some for the lower pressure, correct? I don't want to band/inner tube the bladder because I've heard that the stock rf20 tubing doesn't hold up well to that, and I don't necessarily want the extra rate of fire associated with the banding. I find myself going through ammo pretty quickly as it is.
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#7 imaseoulman

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Posted 01 September 2009 - 09:07 PM

You're absolutely right that range will be pretty dismal with hornet tanks at stock RF20 pressures. A tank expansion should help, though I've never tried it at that low of a pressure, so I can't guarantee that. Sometimes at low pressures the flow rate isn't high enough to support the extra volume, so I can't say for sure. I'd try it first with just one tank and see what the results are like before doing it to all the tanks.

If you do decide to attempt operating them at different pressures, just throw in a ball valve where you would have put the check valve before the bladder. After the relief valve kicks in you could close the ball valve and continue pumping to further pressurize the hornet tanks. Just an option to consider. Also, if you're concerned about ROF for the RF20, remember the dial that changes the speed; you could just turn it down closer to "single shot" mode and have slower firing, even with a banded bladder. Again, just something to think about.

Good luck.
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#8 snakerbot

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Posted 02 September 2009 - 01:04 AM

Alright, I'll try some stuff out on one tank and see what I can get. I'll update this when I find something that works well.

Time for a parts run!
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