High pressure fittings

[Tweegs]

I’m confused.

Looking for high pressure fittings.
I plan to run the RO at ~250 psi.
High pressure cut-off is set for 275 psi.
Membrane housings are rated for 300 psi.
Membrane I/O are ½” NPT.

Thought I would run copper. Types K,L and M will take the pressure, but will probably go with L (rated working is 625 psi @150*).

Options for fittings then would be sweated, flare or compression.

Sweated are out. I’m not that good at it anyway, beyond the other concerns of strength and maintenance.

Compression would be the easiest, but the big box stores have them rated for only 125 psi.
I assume this lower rating is related to the compression bond and not the material.
(odd that my needle valve is compression type and rated for 5,000 psi)

Flare fittings I’m having trouble finding a rating for.
Seems to me the weakest link would be the tube at the flare, but I can’t confirm.

Looked at some poly-vinyl (something or other) tube that could take the pressure. Minimum order was 100’, I need maybe 10 or 15’…copper was cheaper.
And again came the question of fittings. Even the John Guest line of fittings I’ve read much about here aren’t rated for 300 psi. (perhaps I’m looking at the wrong fittings?).

So who’s using what and why?

[BreezyHill]

Sweat only for me. Clean both ends past the joint end with sand cloth, flux both ends, slide together and use silver soldier. When heating you want to heat the entire area to be connected to the point that the soldier melts and quickly move the soldier end around the joint. The soldier is actually cooling the connection and connecting the two surfaces. Don't get the pipe to hot as this weakens the pipe. Cleaning is 90% of a good connection the other 10% is using just enough to make the fitting and not have extra into the pipe.

Compression fittings will leak over time due to sugar and mineral into the fitting.

I have seen where shark bites fittings have let loose...not pretty.

[WESTVIRGINIAMAPLER]

Soldering is easy as said as long as you clean and use plenty of flux. To me flux is just as important as cleaning, one won't work without the other and not hard even upside down. Solder will run where the flux is just make sure it is lead free solder.

[Tweegs]

Thanks guys,

I’ll give it a go.

[maple flats]

Also use a flux rated for lead free. If you get silver solder it will be the strongest.
Before you put the torch to the joint being soldered a 100% cleaning with either a SS brush or plumber's cloth is needed. Flux the pipe and push it into the fitting (be sure to clean both parts completely). Then put the tip of the torch flame (adjust it to the point where the light blue in the flame gives you about a 3/4" point), the rest of the flame outside that will be maybe 2.5-3.5" long). On sizes under about 1.5-2" you only need to heat from 1 side. Then while heating you will first see the flux bubble and then dry up, after that every 2-3 seconds touch the solder to the joint, opposite the flame side. When the solder melts remove the flame and run the solder around about 2/3 the diameter, but not on the flame side. If it draws in good that's it, if the solder does not melt that far around, just put the flame to the fitting again, but it usually will only take 2-3 seconds more. Then wipe the joint with a clean cotton cloth and you are done. The heat will have drawn the solder to cover the entire joint. Do not get the fitting or pipe too hot or you will burn the flux and the joint may leak. That is why you keep testing by touching the solder to the joint as you heat and remove the heat when it melts. It should melt fast, if it just does a little and quits melting you need more heat. If you are still not sure, I'll try to find a decent u-tube link for you. But don't just do a search on U-tube, lots of wrong methods are there to confuse matters.
Here's a link to help. He cleans it well, but used too much solder on the horizontal joint, he left it, I'd just give it a quick touch with the torch and wipe it with the damp cotton cloth. www.youtube.com/watch?v=nmccA2k9VCA
The only difference on your soldering is that you would do better with a silver solder and a flux (liquid or paste) intended for silver soldering.

[Clinkis]

My RO is combination copper with sweat joints and John guest plastic......no problems with either one. Usually run around 275 psi. Actually blew end cap of membrane housing twice when pressure crept over 300 psi when I was not paying close attention. Made a mess but none of my plumbing leaked.

[DoubleBrookMaple]

My RO is combination copper with sweat joints and John guest plastic......no problems with either one. Usually run around 275 psi. Actually blew end cap of membrane housing twice when pressure crept over 300 psi when I was not paying close attention. Made a mess but none of my plumbing leaked.

I guess I should order the high press s/o switch and throw it onto my R/O build in progress!

[Clinkis]

I guess I should order the high press s/o switch and throw it onto my R/O build in progress!

Definatly....planning on retrofitting mine with one before the start of this season

[Tweegs]

With 35 years in electronics, I’m quite comfortable with the principles of soldering.

A number of household repairs and building my preheater taught me, however, that soldering wire and components and sweating copper are two different animals.

The preheater used 1 inch manifolds and five ¾” runs, 50 sweated joints in all and 3 failed under just head pressure.
Let’s not talk about the number of times I had to scream at the wife “TURN IT OFF! TURN IT OFF!” on those household projects.
’Tis why I baulked at sweating anything for high pressure.

Based on how you guys have responded, I’m thinking my problem was too much heat.
I’ve been good about making sure the parts to be joined were properly cleaned and fluxed.

This project is all half inch, I haven’t had too much trouble with that, except for the one time…ah, never mind.

I am curious though, I was planning on bending the copper wherever possible (I have the tools), but let’s talk a moment about the fitting that threads into the end caps of the membrane housings.
I assume you wouldn’t thread the fitting in and sweat that first joint, thereby transferring all that heat to the end cap (plumbers tape, too).
Maybe sweat a piece of 3 or 4 inch straight section to the threaded adapter first, mount the fitting to the end cap, then sweat an elbow (or what have you) on the opposite end and pick it up from there?
That would help reduce the amount of heat on the endcap itself.

And if you were to hard plumb right up to the end cap, how would you remove the cap later (short of putting 350 psi on it, that is)?
Better make sure you’ve got that fitting threaded in tight enough before sweating in the rest of it, too.

Having a little trouble getting my head around that end of it.

[BreezyHill]

I use a union 2-3" above the threaded piece.

Another rule in soldering is you do not touch the connection area after it is shinned. The oils in your skin are very hard to clean off.

With that high a percent of failure I would guess you inadvertently touched the fittings or your flux is contaminated. I like paste or gel flux over liquid. When you slip the sections together give a turn to spread the flux and use plenty to coat all surfaces.

I find wire to be harder than pipe to soldier but this is usually repairs under a dirty salty truck. Tough work environment.

I can get a pic if you want.

[Tweegs]

Touching the parts after cleaning and prior to fluxing is a good possibility, hadn’t thought of that.

A union seems the way to go. Looked at some from the big box stores, really looking for pressure ratings but tripped over the reviews.
80% of the respondents said the stupid things leaked. (1 or 2 bad reviews you can chalk up to idiots, when the majority speaks, however).
Looked at different sources for the unions, but most are from the same manufacturer (Nibco, I believe).
I’ll probably just chance it, unless you’ve got a good recommendation.

Acetone will usually clean those wires up for you. Make sure it all evaporates off before touching the iron to it though.
I don’t know about you, but getting out from under dirty, salty truck quickly isn’t in the cards for me.

Short of the acetone, I’ll cut the wire back until the strands are clean and splice in a new wire.
For that environment, cover the splice with heat shrink, the type that has a hot melt glue in it.
Butt splices work, temporarily, but corrode quickly (dissimilar metals).
Where you have to use crimp on connectors, a dab of Nolux or other dielectric grease will help keep corrosion at bay.

[Zucker Lager]

Hey Guys check out this PDF everything you ever wanted to know about copper pipe and tubing and more. Jay

http://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf

[jimsudz]

i used compression and flare fittings without any problems.

[jimsudz]

I should state that I run 300 psi and less. It's an RO not a log splitter

[BreezyHill]

Tweegs,
Acetone, I will have to give that a try.

sons and their friends have seen a few hot welder drip dances over the years. lol

Shrink tubes are great, I add a dab of silicone to the joint and the shrink tubes spread it very well. Joint lasts indefinitely.

Thanks for the tip!

Ben