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Finished Lpa Tank


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#1 jackster57

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Posted 28 July 2008 - 02:12 PM

EDIT- TANK IS COMPLETED! Scroll farther down for pics. Write up is coming

I have a plan to build (in a way ) a simplified and less expensive version of CS 's LPA tank. I would use this tank on my magstrike only. This tank would let me shoot alot more shots and give me the option of using a double clip.

My plan for this build was to use 1.5'' sch 40 pvc as the tank. Then on one side of this 1 foot or so section of PVC goes an end cap. A bike pump/shader valve gets drilled into the endcap and is made airtight with Plumbers goop. On the magstrike i would connect a coupling to the flexible tubing that comes out of the trigger valve , I would then attach more flexible tubing (about a 2 foot section) to the coupling then attach it to the tank. I would pump up the tank with a bike pump via the shader valve. Then when I pulled the trigger of the MS the air would be let out from the tank to the tubing that connects into the magstrike tank.


Drawing ...

Posted Image

Now for questions.

#1- Would I be able to pump up the tank with out the tubing bursting , considering that the air will be able to flow freely from the bike tire valve to the magstrike trigger?. I would plan on filling this tank up to around 65 psi.

#2 What would the best way be to connect the flexible tubing to the 1.5'' sch 40 PVC tank?

Will those of you that have experience with these kinda things please help me out.

Edited by jackster57, 30 July 2008 - 11:06 AM.

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#2 UpperHand

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Posted 28 July 2008 - 02:26 PM

Jackster57,

I know I am new to NH but I have been nerfing for a little over a year now, so I'll try to help out:

I'm not sure whether or not you mean the tubing in the magstrike or the tubing you are going to buy, but if you buy pressure rated tubing for the tubing you should be good. I got some at McmasterCarr.
As for the connection of the tubing to the Pvc tank, I'm pretty sure that you can get a PVC pipe to tube adapter easily at your local hardware store. If not, there's plenty of sites that you can buy those at. I think they are called hose barbs

-Upperhand
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#3 jackster57

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Posted 28 July 2008 - 03:35 PM

Thanks. Also, does anyone know what the specs of the magstrike tubing are?
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#4 DTReaper

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Posted 28 July 2008 - 03:55 PM

Without a regulator in between the tank and gun there will be a pressure drop and so as you shoot more your range will go down because the tank is solid and does not change volume. That is why nerf uses the bladder system it changes volume to keep a more stable pressure. So will it work most likey but it will only work for a while before it goes down to an unusable pressure.

I believe CS did actually stat the pressures somewhere in his thread and he did indeed start with a PVC built tank but he had a regulator so if you want to go for it.

-DTR

Edited by DTReaper, 28 July 2008 - 03:56 PM.

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#5 jackster57

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Posted 28 July 2008 - 04:32 PM

I just got all the stuff at the local hardware store. Also, thanks for the warning about the PVC. Ill post the completed pic later today. Total cost = 15$ + magstrike
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#6 CaptainSlug

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Posted 29 July 2008 - 11:06 AM

DO NOT fill a PVC container with more than 90psi of gas pressure.
pneumatic pressure and hydraulic pressure do not have the same power curves and PVC pipe is not designed for pneumatic pressure. So if it fails under the stresses of pneumatic pressure it's far more dangerous than when it fails under the stresses of hydraulic pressure.

1. My plan for this build was to use 1.5'' sch 40 pvc as the tank.

2. A bike pump/shader valve gets drilled into the endcap and is made airtight with Plumbers goop.

3. Would I be able to pump up the tank with out the tubing bursting , considering that the air will be able to flow freely from the bike tire valve to the magstrike trigger?. I would plan on filling this tank up to around 65 psi.

4. What would the best way be to connect the flexible tubing to the 1.5'' sch 40 PVC tank?

1. This is not going to offer you enough volume. My LPA tank provides 145ci of volume at 80psi and is down regulated to 60psi. And I only get 80 shots from it. What you are proposing will only net you 24ci.

2. If your schrader valve is the press-inset type with a rubber grommet molded into it then you should not be using any epoxy or sealant with it. You should only use plumbers goop to seal threaded fittings.

3. The tubing in the magstrike is pretty crappy stuff and will burst at pressures as low as 70psi. It's also prone to kinks.
Since the trigger valve has compression fittings I found it easier to just unscrew the compression nut and replace the stock tubing with a more durable tubing of the same dimensions. This new tubing then connects to a barbed tubing fitting, a threaded coupler, and then an instant tube fitting so I can use a much more durable type of tubing outside of the blaster to go inbetween the tank and the blaster itself.

4. I prefer instant tube fittings, but you could just go directly from the compression fitting on the trigger vale to a matching size barbed tube fitting on the tank using a single length of one tubing size.

Edited by CaptainSlug, 29 July 2008 - 11:10 AM.

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#7 jackster57

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Posted 29 July 2008 - 12:33 PM

Thanks for your help CS. I think I got a pretty reliable system worked out. If I do find that I do not get enough volume I will most likely upgrade to 3inch PVC. I am still waiting for all my goop to dry then Ill take a test.
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#8 jackster57

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Posted 30 July 2008 - 11:04 AM

Results....


PSI = 60

Shots = 32

Range = 50 on average ( Non- Banded piston)

Pump time with bike pump = 20 seconds

Verdict = I have successfully completed a LPA tank for under 20 bucks! Expect a write up later today.

Pics-

Posted Image


Posted Image



Write Up Coming....
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#9 imaseoulman

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Posted 30 July 2008 - 01:03 PM

So, in a couple of the recent magstrike mods I see that the front has just been cut open with nothing there to squeeze it together. Does this allow the firing off of just a few shots? Or do you have to fire the whole clip at once? Thanks.
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#10 jackster57

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Posted 30 July 2008 - 01:09 PM

I dont really understand your question. I just cut open the front so I could make a 20 round PETGed clip, but other than that it does nothing to affect performance.
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#11 Doom

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Posted 30 July 2008 - 08:51 PM

I just want to warn you that your PVC caps are definitely DWV and are not pressure rated. Their socket length is far too short to be pressure rated. Since your tank is so small to begin with I'd highly suggest scrapping it and looking to make a larger chamber. SpudFiles has a great page on identifying pressure rated pipe and fittings. I personally avoid any pipe that doesn't have a pressure rating written on it (regardless of whether it's DWV or not because there can be DWV pressure rated pipe) and only use fittings that are NSF-PW or NSF-61 rated (they're the same rating but have different names).

Let me reiterate that the tank you're using is dangerous. I would not suggest using it. Build a newer larger one with pressure rated parts and a regulator like CaptainSlug's... you'll appreciated the regulated pressure and not having to pick PVC shrapnel out of your body.

Edit: With all that being said your tubing probably isn't pressure rated either. I've never seen a pressure rating for normal vinyl tubing but I have pressurized it (with water, though). The difference between the tubing and PVC is that the tubing won't explode and turn into shrapnel like PVC will during failure. Your tank will probably break first at the tubing connection but I'd still play it safe with pressure rated parts.

Edited by Doom, 30 July 2008 - 08:54 PM.

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#12 Lynx

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Posted 30 July 2008 - 10:39 PM

Just scale down CS's plan, make sure you use pressure rated materials and if you doubt it's strength, just put some denim around the tank. It is VERY strong fabric.
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#13 jackster57

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Posted 31 July 2008 - 07:04 AM

Thanks Guys. This tank has sprung a leak any how so I will redesign it. I have 2 reasons why I didnt want to make CS's tank, reason 1 is COST. CS's tank costs around 90 bucks shipped Thats a lot of money for a DIY tank. I am looking to spend less then 40 bucks on the whole thing. Reason 2 is BUYABILITY OF PARTS. I got all of these parts at my local hardware store.
Thanks for all of your concern with safety. Now that I look back on it I realize how dangerous it was. I will probably make a Hybrid of CS's tank and this tank. But MUCH safer. I have decided to scrap this one.

THANKS AGAIN,

Jackster

Edited by jackster57, 31 July 2008 - 07:07 AM.

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#14 eddieoctane

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Posted 01 August 2008 - 05:19 PM

Jackster57,

I know I am new to NH but I have been nerfing for a little over a year now, so I'll try to help out:

I'm not sure whether or not you mean the tubing in the magstrike or the tubing you are going to buy, but if you buy pressure rated tubing for the tubing you should be good. I got some at McmasterCarr.
As for the connection of the tubing to the Pvc tank, I'm pretty sure that you can get a PVC pipe to tube adapter easily at your local hardware store. If not, there's plenty of sites that you can buy those at. I think they are called hose barbs

-Upperhand


Barbed fittings are alright, but I would throw a hose clamp on for good measure.

And if you are really worried about kinks and pinches in the house, braided hose could be an option. It just won't be cheap.
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#15 CaptainSlug

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Posted 02 August 2008 - 10:11 PM

Barbed fittings are alright, but I would throw a hose clamp on for good measure.

Some sizes and types of barbed tube fittings are not compatible with hose clamps or zip-ties. So ymmv
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#16 thedap

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Posted 16 August 2008 - 09:11 PM

I know the local homey despot sells short sections of PVC pipe cheaper than full lengths.
it could help keep you in budget if you go bigger sized pipe.

if you need to thread pvc and don't have a tap to do it, you can take a threaded pipe of the same size you need and cut it along its length at the threads, five or 6 places around the outside. so it looks like a self tapping screw on steroids.

then if you start to work it into your hole you predrilled, it will cut the threads. make sure it is not skipping and back off constantly to clear the shavings.

they make a shrader valve assembly for aluminum rims. it looks like a metal mushroom almost. it has a rubber washer under the head to seal on the inside of the rim and a nut that screws down the stem on the outside. it can be used on just about anything with a hole drilled in it. the area under the mushroom head has to be fairly flat so the rubber can seal properly.

also, your shrader doesn't have to be on the tank at all. it could be inline between the tank and gun or on the gun itself.

you could even mount a small bike pump permanently to the tank or the gun.
I've picked up nice little bike pumps on sale at target and at the local dollar stores.
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#17 imaseoulman

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Posted 16 August 2008 - 09:16 PM

I dont really understand your question. I just cut open the front so I could make a 20 round PETGed clip, but other than that it does nothing to affect performance.

I'm wondering if the clip falls back down if you try to fire off only a few shots. You know how the etape mods prevents the clip from falling back down? Well, I was wondering if cutting open the front makes the clip fit loosely so that it falls back down if you don't continuously fire.
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#18 Thom

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Posted 17 August 2008 - 03:49 PM

By the way, that Magstrike looks beautiful chopped down like that.
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#19 jackster57

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Posted 24 August 2008 - 08:58 AM

[/quote]
I'm wondering if the clip falls back down if you try to fire off only a few shots. You know how the etape mods prevents the clip from falling back down? Well, I was wondering if cutting open the front makes the clip fit loosely so that it falls back down if you don't continuously fire.
[/quote]


Nope. Its fine even with it cut open. It only fell in for me if I shook it when the clip was up, but some etape fixed that.

Thom - Thanks. Also chopping it down makes is have like 7 total screws.
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#20 imaseoulman

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Posted 24 August 2008 - 09:52 AM

Thanks jackster, I'm definitely going to have to try this.
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