QEV vs. Solenoid

[Atattack]

I was planning on using a 3/4" QEV for a cannon with a 4" x 36" galvanized steel chamber with 2" x 72" barrel. Would I be better off going with a 1.5" solenoid valve? First cannon and would appreciate the veterans opinions. Thanks in advance guys.

[Crna Legija]

I was planning on using a 3/4" QEV for a cannon with a 4" x 36" galvanized steel chamber with 2" x 72" barrel. Would I be better off going with a 1.5" solenoid valve? First cannon and would appreciate the veterans opinions. Thanks in advance guys.

you could have ask this in your other thread, yes a 1.5'' sprinkler valve will be much better. A 3/4'' QEV is only good for a barrel around 1'' in dia not much more.

[nathanhd123]

Go with the solenoid. Using a 3/4" QEV would really restrict the flow and it would be very pricey buying a big enough one.

[Fnord]

The 3/4 qev will limit the flow/power considerably with that setup, but if you just want a quick proof-of-concept launcher, it'll work. You can upgrade later.

What 1.5" valve you are considering? Most valves can be converted to function better when the solenoid part is removed.



^^ Edit... ninja'd twice in three minutes, lol

[Atattack]

I have not decided on a 1.5". I want to be able to fire it from a distance of 30 feet away. Do you have any recommendations. I am curious how much a valve that large would cost. I need it to be rated to at least 300 psi.

[Fnord]

Ok, 300 psi is a very high rating for a non-industrial valve. You'll find large sprinkler valve rated to 200 or so, but they'll be expensive unless you find them on ebay or a surplus store.

Also, with 300 psi your chamber is really oversized for your barrel. What are you planning on filling it with?

[jackssmirkingrevenge]

I need it to be rated to at least 300 psi.

That eliminates a sprinkler valve...

[Fnord]

Hey jsr, do you remember that cannon posted last year(?) that had a massive 2" brass solenoid and custom welded chamber? It was a nice curvy under-over. I can't seem to find it but it's probably a good example of the price range...

[Atattack]

I probably should have given a little background info on the design. I am hoping to use it at different pressure for different objects such as potatoes for higher psi and water balloons for lower psi which is why I built such a large chamber. I will probably be operating the gun mainly around 100-150 psi form the water balloons and higher for the potatoes. That is why I am having trouble deciding on a valve. I really do appreciate the help guys.

[jackssmirkingrevenge]

Hey jsr, do you remember that cannon posted last year(?) that had a massive 2" brass solenoid and custom welded chamber? It was a nice curvy under-over. I can't seem to find it but it's probably a good example of the price range...

This one?

Thisis the valve in question, doesn't look cheap.

I am hoping to use it at different pressure for different objects such as potatoes for higher psi and water balloons for lower psi which is why I built such a large chamber. I will probably be operating the gun mainly around 100-150 psi form the water balloons and higher for the potatoes.

A fast valve will likely destroy a water balloon at that pressure before it even leaves the barrel.

Two important parameters to consider:

- what sort of performance were you hoping to achieve

- what budget do you have

Also good to know, what sort of tools and materials do you have available?

[Atattack]

I have already purchased the pipes and some of the fittings but can return them if needed. I would like to keep the rest of my budget under $250 if possible. The facilities I have are decent and I have a friend who has a full metal shop but lives 5 hours away so am hoping to complete most of work with limited tools and knock out the complicated stuff in one day.

The pipes I currently have are 4"x36" galv steel, and 2 2"x36" galv steel. I had same concern JSR about bursting balloons but thought if I only use 75-100 psi on balloons with a foam cup behind it that would help, your thoughts? Also would like ability to go up in PSI to launch solid projectiles far distances. May not be feasible to have both in same gun but was hoping if I used different psi's it would help.

Starting to wonder if I should go with a piston design. Thanks guys.

[jackssmirkingrevenge]

A piston valve would certianly give you good performance at a much cheaper price, but it will need a bit more work.

What were you planning on using as a pressure source?

At the 150 psi a shop compressor can give you, and the dimensions you are proposing (3 foot 2 inch barrel, 3 foot 4 inch chamber), you'll be sending potatoes into the next county.

With a 2 to 4 inch reducer, 4 inch endcap and some cutting and welding, a coaxial piston valve would be a very realistic prospect. You'll lose some chamber volume but it won't have a visible effect on performance, and on the upside the launcher will be half the length, not sure if compactness is an issue for you.

Is the 4 inch pipe smooth internally?

a foam cup behind it that would help

You'll be amazed how few psi you need to destroy one but wadding is something that can be discussed later.

[Atattack]

I think a Piston with a gun with these dimensions will be the way to go. I considered it at first but with this being my first gun was a little worried to try it. I will have to check how smooth the pipe is internally. It is schedule 40 galvanized steel that is new. I should be able to sand it right? Does only the section where the piston will move need to be smooth?

Also, is there a good how to guide on putting a piston gun together? Not sure how to secure the barrel to the 4"-2" reducer and what to make a piston that large out of.

[mattyzip77]

[quote="jackssmirkingrevenge"]A piston valve would certianly give you good performance at a much cheaper price, but it will need a bit more work.

How do you think a 1 1/2 inch q e v would work, rather than the piston???

[jackssmirkingrevenge]

I think a Piston with a gun with these dimensions will be the way to go. I considered it at first but with this being my first gun was a little worried to try it.

For absolute beginners I would not recommend it, but for those with previous material experiences with plumbing it's not that big a deal.

I will have to check how smooth the pipe is internally. It is schedule 40 galvanized steel that is new. I should be able to sand it right? Does only the section where the piston will move need to be smooth?

Yes, if the pipe has a seam it will need to be filed and sanded down to allow the piston to move easily.

Also, is there a good how to guide on putting a piston gun together? Not sure how to secure the barrel to the 4"-2" reducer and what to make a piston that large out of.

It's a question of understanding the concept and applying it to the materials and tools you have to hand. I'll draw up a little diagram, in the meantime does your friend have a lathe on which he might be able to machine a piston from nylon, delrin, PVC or any other suitable polymer?

How do you think a 1 1/2 inch q e v would work, rather than the piston?

Is there a QEV of those dimensions that can be purchased at a reasonable price?