Pressure Gauge Placement and Other Propane Stuff

[revans]

Hey guys, I've looking at making a propane injection system and after looking at tutorials and other people's launchers I've deduced that:
1) The regulator (if there) needs to be right by the propane tank to be useful (right?)
2) If you don't have a regulator (and your using plastic pipe like me) you should have a few wraps of pipe to let the propane evaporate into gas before it reaches the plastic so it doesn't go brittle.
3) Pressure gauges can either be placed at the start of the system with the regulator or in the middle of the meter between the ball valves.
Does it make a difference where the gauge is positioned? Does any one have any opinion on this or anything else I've said? Just want to check before I empty my wallet. Thanks for any help or suggestions. Cheers, Rhys

[MrCrowley]

1) You don't need a reg, it does help though and yes, before the meter.
2) Not sure on that, why not metal? It's pretty much the same price or cheaper.
3) Seeing as I can get a regulator that has a guage for about $5US, I actually have a guage on the reg, and in the meter, just to make sure.

But you can either have a reg with guage, or a guage in the meter. You don't need both.

It shouldn't make a difference, the reg is just more reliable and usually more accurate.

[Pete Zaria]

I'd always prefer to have the gauge on the meter pipe, between the ball valve so I can see the exact pressure (and thus amount) of propane being injected into the chamber.

The regulator is optional - I, along with a few other "combustion experts" here like SpudBlaster15, etc... have used propane injection systems without a regulator without problems.

As I mentioned in another thread, the problem with compressed gases in plastic pipe is that as they evaporate from the liquid state to the gas state, they become very cold which can make the plastic pipe brittle. So, either keep your propane tank upright all the time, or devise a system to make sure no liquid can get to your meter, such as a coil or two of pressure-rated hose between the tank and meter pipe or etc...

Good luck

Peace,
Pete Zaria.

[revans]

Thanks for the info, I think I'm going to go for a gauge in the meter and either a regulator or loops of hose. Also if I was to use a regulator would this one be okay?: http://www.topmaq.co.nz/product_detail.aspx?id=AIAC6100
Mr Crowley, seeing you're from NZ, if you know where I could get a cheap without-gauge regulator that'd be great.

[MrCrowley]

Oh yeah forgot your a Kiwi
Those Topmaq regs I linked to you in that other thread will be fine.

For $9 you can't go wrong, may as well keep the guage and just do what I do and chuck another guage in the meter if you're that way in mind.

You'll pay $25 at SuperCheap for a similar guage, so just get the topmaq one.

[revans]

Cheers Crowley do you think that the budget brass regulator I linked to above would work though? even if the slightly more expensive ones you showed me with gauges might be better. BTW For my gauge in the meter I plan on using another cheapo from Topmaq: http://www.topmaq.co.nz/product_detail.aspx?id=PUEL5030

[MrCrowley]

Yeah it would work, though this one can be found on trademe for $9:
http://www.topmaq.co.nz/product_detail.aspx?id=AIAC6150

Choose what you want, both will work.

Not exactly cheap, but sure it will be fine. Topmaq seems almost as expensive as SuperCheap, you could get this stuff half price at a plumbing/gas merchant.

BTW How old are you? If you're young and innocent looking like me, they might give you it at trade price if you go to a plumbing merchant like LG Carder (Now Reece).

[revans]

I'm in 6th form at high school so that could work The only thing I got a problem with though is what you said in that other thread about propane bottles have weird sizes so you can't connect anything (like a regulator) to them. I don't know how to get around that.

Also, do you know the rough dimensions of those Mitre 10 propane bottles?

[MrCrowley]

Ha! I'm 6th form too

You're in luck, I figured out a way and posted a quick how-to on it <A HREF="http://www.spudfiles.com/forums/viewtop ... 7">here</a>

Hmm I have two of them, all I know is that they fit in 3" DWV PVC pretty tight. They're the same as the ones on this site, so maybe a few Americans or Canadians will have better specs.

[revans]

Cool, that propane adapter thing seems pretty nifty. Except for: what's size 14 metric drill bit, 14mm or something? and how do you drill through solid brass? i tried drilling through a thick bolt once and got nowhere. oh yeah and this would do right?: http://www.hoseshop.co.nz/product-detai ... prodid=476

[MrCrowley]

No idea, but it's the same size for all metric drill bits, whether it's a spade bit or a normal drill bit. Just go to Mitre10 and a size 14 drill bit will be the same size.

I used a 10mm drill bit, then seeing as I had two 14mm brass spade bits, I wasted one on the brass fitting. The bit is completely FUBAR'd, but I had two and no other drill bits to use

If you can get your hands on a cheap drill bit size 14 that can drill through metal, try that

If you can't find JB-Weld in stores, try trademe:
<A HREF="http://www.trademe.co.nz/Trade-Me-Motor ... JB-Kwik</a>
<A HREF="http://www.trademe.co.nz/Trade-Me-Motor ... JB-Weld</a>

JB-Kwik takes 24hours to completely set, and only 4hours to dry. JB-Weld, though slightly stronger takes one week to fully set.

So if you're using pressures under 250psi, JB-Kwik will be fine for most things.

Wow, just found 5ounce <A HREF="http://www.trademe.co.nz/Trade-Me-Motor ... ro-Weld</a>, 5x normal size.

[revans]

Thanks for the link to 'the world's finest cold weld adhesive'.
I guess I just need to drill a hole which the torch head pipe will fit through, I'll figure something out. Hopefully my launcher ends up being worth all this time and cashy.

[MrCrowley]

Yeah I know what you mean, I've probably spent about two grand on spudguns in 4 years.

$100 on my first combustion
$500 on a launcher I still haven't finished
$200 on a paintball gun
$250 on my golfball launcher
$30 on a cloud BBMG
$400 in America
$300 on many various parts I still haven't used

Don't know where I get the money from, but I spent it somehow

[revans]

Yeah I need a job eh, I'm running out of money.

[Spitfire]

I made a meter the other day



Then a stupid thing happend



Now i must go spend another R40 for a smaller pipe

sigh