Granta - my copper APH (design phase currently)

[Ben]

Hmm.. I've never heard of non-return valves but alternate names are good to add to the guide. I'll get on that.

[cantab]

Latest possible change to my design: I'm considering using a product called "Just For Copper". It's basically a glue specifically for pipework. It's quite expensive, but the cost can be saved back by the use of the very cheap, and also light, end-feed solder fittings. It's pressure rated to 500 psi.

http://www.solderlesscopperbonding.com/pg/index.html

[devvo]

why dont you want to solder your fittings, soldering capillary fittings is very easy, just get the ones with solder inside the fitting, there just heat and go and cost 30p a fitting

[cantab]

Hmmm...I'm not really sure. I think it's in part because I know the people I'm staying with now won't like me using a blowtorch. In any case though, I might postpone the build until I go back to uni, that way I don't have to transport the gun; since I'm going by train, luggage space is at a premium.

[Ben]

Yeah, you should probably go with soldered fittings. I've actually been considering making my own copper gun with soldered fittings for the sake of enlightenment. My father has a torch and he knows how to solder copper pipe so it shouldn't be too difficult. Sadly I don't have infinite time or money.

[Silence]

Just For Copper sounds like JB Weld, but just for copper. Anyway, if it's easy to use, go for it!

[cantab]

Latest on this is I'm going to postpone it until I return to uni and get my student loan.

Also, does anyone know a cheap source of check valves in the UK? It seems like they're going to be the most expensive parts (well, them and the nozzle valve), so if I can save money there that would be great.

Also, is it possible to make a quick filling gun without using a check valve. I'm thinking basically connect a hose to the nozzle, open the nozzle valve, close when pressurised, remove the hose, sorted. If that will work, I'll probably use my leftover pipe and fittings from Granta for such a design, named 'Nene'.
In fact, I might try and rig it up so that Granta and Nene can be connected nozzle-to-nozzle, then pumping Granta pressurises both, then they are seperated into two guns again. That way I only have to build one pump.

Aside: more confusion on valve nomenclature - the term 'ball valve' in the UK most commonly refers to the automatic valves used in toilet cisterns, http://en.wikipedia.org/wiki/Ballcock

[aEx155]

Originally Posted by cantab

Also, is it possible to make a quick filling gun without using a check valve. I'm thinking basically connect a hose to the nozzle, open the nozzle valve, close when pressurised, remove the hose, sorted. If that will work, I'll probably use my leftover pipe and fittings from Granta for such a design, named 'Nene'.
In fact, I might try and rig it up so that Granta and Nene can be connected nozzle-to-nozzle, then pumping Granta pressurises both, then they are seperated into two guns again. That way I only have to build one pump.

You could always make a detachable put and make it fit onto both guns. If you make your pump and attach it with some quick-disconnect fittings (male on pump and female on gun; get the kinds with the stop in them so the water won't flow out when you disconnect the pump) and just make a "pump space" to fit the pump into, then you can pump both up without having to do that "nozzle to nozzle" thing. (you could also use the QD for filling from a hose)[... but then again, I think you're going after filling both guns up at the same time.] Just a thought.

As for your hose to nozzle idea, I guess that would work, but since there would still be pressure in the hose, you'd get soaked. I used to do that when my pump broke, and I had to figure out a way to disconnect the hose while not getting wet. If you were going to do that, I recommend you get a female QD with stop (to keep the water from spraying out) on the hose and put a male one the gun after the ball valve. Connect to fill, close ball valve, disconnect, and fire! If you get the right size, you might be able to use the male QD as a nozzle, too.

[cantab]

I've found a much cheaper supplier for most fittings, especially check and ball valves

www.screwfix.com

(despite the .com address it is a UK company)

so that should save me a fair bit. They only sell pipe in big packs though, so the pipe I'll get elsewhere.

I've also found there that unequal tees are very expensive. It'll probably be cheaper to use an equal tee with a reducer, though making the gun slightly longer.

[Silence]

If you have the right parts, a homemade valve might work. You need the right fitting, an olive, a ball (like a large BB/slingshot ammo, a marble, or a hard rubber ball), and a spring. That does get a little complicated though.

Ben's 2 liter homemade water gun uses a ball valve instead of a check valve.

[devvo]

www.plumbcalldirect.co.uk have cheaper fittings than screwfix also www.plumbworld.co.uk, just dont get any brassware from plumbworld though, there notorious for sending out conex branded rubbish.

[cantab]

Originally Posted by Silence

a ball valve instead of a check valve.

Ball valves are even more expensive than check valves...

Originally Posted by devvo

conex branded rubbish

Would you say conex should be avoided then?

[devvo]

avoid conex if you can, there compression fittings always seem to nip the pipe so it kinks slightly at the nut which also leaves it open to bending, not a major problem when chucking it in a house as it wont be moving but a water gun thats being thrown around.... you get the picture.

get crane or yorkshire if you get a choice, that 20p more could save you having to rebuild whole parts of the watergun.