19 replies to this topic

[Nonsense Man]

Well I found This but it's kind of expensive and I don't know how to mount it. Well I am making a homemade gun and i will have a cheap pump connected to a 1/2 inch cpvc tank but I want to know the PSI in the tank so uhmm what is a cheap PSI gauge and how would I connect it to my setup.

[PvtMcFlurry]

So your using a piece of 1/2 CPVC as a tank if I'm not mistaken. Sounds to me like your name suits you perfectly.

[nerfturtle]

You call 15$ expensive? I think that one is made for hooking up to tire valves, so if you want one you could just go to the hardware store and find some all-purpose PSI guage. As to hooking it up to a gun, you could just drill a hole in the top of the air tank and goop the guage into the hole.

[Nonsense Man]

Well the CPVC has a pressure rating of 400 PSI. Also this is an attempt to be like a DCAP or whatever it was that CS made.

Edited by Nonsense Man, 29 August 2007 - 09:13 PM.

[SHADOW HUNTER ALPHA]

Well the CPVC has a pressure rating of 400 PSI. Also this is an attempt to be like a DCAP or whatever it was that CS made.

Not the point. 1/2" CPVC pipe, no matter the pressure rating, is not going to hold such a large volume of air that you could possibly hope to do anything with it.

[Nonsense Man]

Ok then scratch the 1/2 cpvc ill use a different tank just could someone just help me with the regulator..

[Quilan Fett]

Well the CPVC has a pressure rating of 400 PSI. Also this is an attempt to be like a DCAP or whatever it was that CS made.

Not the point. 1/2" CPVC pipe, no matter the pressure rating, is not going to hold such a large volume of air that you could possibly hope to do anything with it.

Also, 1/2'' PVC has like a 1200 PSI rating, but is not safe over 100 PSI.

[CaptainSlug]

The pressure rating on PVC pipe is for WATER PRESSURE which is not the same thing as GAS PRESSURE. Do not fill any kind of PVC container that isn't rated as SCH40 or SCH80 above 100psi of constant gas pressure. Anything higher than that at constant pressure and the pipe is pretty likely to fail (i.e. explode/crack etc.).

The cheapest pressure gauge I've used is $6 and is available through mcmaster (part# 40565K51) and is available in pressure ranges up to 60, 100, 160, 200, and 300. It's 1/8 NPT threaded so you either need a threaded adapter to screw it into, or you have to drill and thread a hole using a tap.

When I made the DCHAP-1 I used 1-1/4" SCH40 PVC as the blast chamber. You need atleast 1" pipe to make a sensibly sized tank for a single shot.

Edited by CaptainSlug, 29 August 2007 - 09:38 PM.

[Nonsense Man]

Ok I think I'm doing a big order with Mcmaster one last thing thought where would i get a stepdown from Sch40 Pvc to a ball valve made for 1/2 cpvc. Actually one more thing where can I find a threaded adapter??

[CaptainSlug]

Search mcmaster for "plastic pipe fittings" and you'll see all of the available options for various pipe parts.

Here's a list of parts

<- Brass 1/8 NPT Threaded Tee or Cross with Pressure Gauge and pump input ->

<- Brass 1/8 NPT hex nipple ->


48335K207 - HI-Strength White Nylon Threaded Pipe Fitting 3/4" Male X 1/8" Female, Reducing Hex Bushing = In stock at $1.30 Each


4880K203 - Std-Wall (Schedule 40) White PVC Pipe Fitting 1" Pipe End Male X 3/4" NPT Female, Hex Bushing = In stock at $0.82 Each

Bushings have the same OD as the pipe so to glue them to the end of the pipe you have to use couplers.


4880K73 - Std-Wall (Schedule 40) White PVC Pipe Fitting 1" Pipe Size, Coupling, 2-3/32" Length = In stock at $0.48 Each

<- Length of 1" SCH40 PVC Pipe ->


4880K73 - Std-Wall (Schedule 40) White PVC Pipe Fitting 1" Pipe Size, Coupling, 2-3/32" Length = In stock at $0.48 Each


4880K314 - Std-Wall (Schedule 40) White PVC Pipe Fitting 1" X 1/2" Sz, Pipe End Male X Socket Fem, Hex Bushing = In stock at $0.74 Each

<- Very short Length of 1/2" SCH40 PVC Pipe ->

4876K51 - Economy PVC Ball Valve 1/2" Socket Connection, White Body = In stock at $4.98 Each

<- Length of 1/2" SCH80 CPVC Pipe for the barrel ->

Edited by CaptainSlug, 29 August 2007 - 11:50 PM.

[Prometheus]

Here you have several options:

Use standard SCH 40 PVC
Use high pressure SCH 40 PVC (a darker grey than regular SCH 40)
Buy a cheap 2" dial pressure gauge, like CS said. If you want a really high pressure, such as 30-350 psi, I migh be able to get you a high pressure compressed gas regulator (used on HVAC systems). It has one pressure gauge, but you'd want 2, one for pressure input and pressure output.

[commander erik]

Why not just buy a pump (I always use a foot pump) with a guage built in?

It may sound simple, but it works. I may be misunderstanding the purpose a bit, but as long as you are going to fill it via a tire valve, I see no problems arising.

[Nonsense Man]

Well thanks for the help but this is getting put on hold while I make my fully auto electric gun.

[Kid Flash]

i have a question now. if i have 1.5 inch pvc then how much air should i put in? do i only put in up to 100 psi?

[Prometheus]

i have a question now. if i have 1.5 inch pvc then how much air should i put in? do i only put in up to 100 psi?

Is it thin wall, or SCH40, or high pressure SCH 40É I`m going to assume regular SCH 40, so 100 psi should be your upper limit. I think CaptainSlug said they could hold about 120 psi max.

[Kid Flash]

alright. thankyou. im trying to make a pretty powerful air gun but i want to get at LEAST 10 shots off with one tank. ill figure something out.

[CaptainSlug]

do i only put in up to 100 psi?

Correct.

[Kid Flash]

do i only put in up to 100 psi?

Correct.

how long do you think an airtank should be if its 1.5 inch pvc to get off 10 shots? about 1 foot?

[SHADOW HUNTER ALPHA]

How much air will be expended per shot? This question directly affects range, so if you want a long-range rifle, then get a bigger tank. Once you have decided upon this, you can calculate the volume of your tank. (That needs to be about eleven [to allow for marginal errors and better pressure] times the volume of air that will be expended per shot.)