Metal fittings and RO water.

[DarkSoul]

Does anyone know which types of metal fittings are suitable for use with RO systems.

Fittings that wont corrode or leech stuff back into the water?

I'm having some trouble finding exactly what I need (and I need alot of fittings :D) but mostly, I've been looking for plastic.

I picked up a 9.2 Gallon accumulator tank today, but its brand name is unknown, and it has a 1" pipe thread fitting on the bottom.
This fitting is metal of some sort, though it is silver in appearence, I think it may be plated brass or copper. I dont know anything about this particular tank other than it is a water storage tank, which is what I needed.

I am slighty concerned about this metal fitting, and the light powdery coating on the rubber membrane inside (obviously a few flush runs of the tank are in order) I fear that the metal fitting may corrode over time and leech metals into the water.... maybe im just over stressing :)

The only other option would be to pay a (likely) outrageous price to have the cover plate that the nipple is connected to made out of plastic.
There is a company here who could possibly do such a thing, and in the process have the nipple made a smaller size, and female.

Otherwise, back on topic here, can anyone answer the above question about safe metal fittings, and where I may possibly locate a soloution to my 1" male pipe thread nipple problem?

I basically need (want ideally) a plastic reducing elbow that will reduce 1" FPT to 1/4" FPT (probably have to have another reducer of some sort as i doubt any fitting would reduce that much)

[Plecosterone]

Stainless steel or brass are both good choices although stainless is very expensive. Brass fittings can usually be found at most hardware stores and is probably your best bet on finding something that will work. Maybe a plastic bulk head fitting with a brass nipple.

[ct-death]

Generally you want to marry up like materials. When we go from one fitting material (say brass) to another (pex, for example) there are often fittings made to do that specific task and they are usually designed in a tongue and collar fashion. Threaded materials will seperate over time, particularily in an environment where the humidity and/or temp flucuates (sp?).

As to you question; Heavy metals can always corroroed and more to the point, build up over time in standing water. Leaching can also occur. However, this takes years oftentimes, or longer, and besides which the water itself starts from your own home where that same water has had time to work on your copper pipes and brass fittings there - Especially standing water in pipes. Water used frequently flushes the particles before they tend to build up in amounts. Some elements are very important even at extremely low concentrations (i.e. lead, arscenic, etc.)

Even if metals are leached out from this one fitting, we are talking very very small amounts from one metal fitting. The water passing through a entire homes pipes, sure you may have trace elements, but nothing measurable from a single brass/stainles steel fitting.

Hope this helps. Grandfather is a master plumber - Man do I save a lot of $$$ :D

[DarkSoul]

The storage tank is storing water from an RO filter..... so after my cities copper pipes, it goes through my filter, which removes EVERYTHING, and I do mean everything.

This tank will be storing nothing but the purest of pure water(UV/RO/DI water) so I wanted to reduce the contact between metal as much as possible.

[ct-death]

Ooh I like that! :D

Yeah, if you are going to this length to ensure pure water, if would be best to go all plastic IMHO. NOt that I can foresee 1 fitting cuasing any issues, but peace of mind and making a system like this "perect" would be a good goal.

Nice setup Darksoul (like the name too) ;)

[DarkSoul]

to be quite honest, if I KNEW this fitting was stainless, I wouldn't be so concerned, but the flange plate on this tank, honestly looks like nothing more than plain old steel.... which as we all know, rusts :)

But I find it hard to believe a water storage tank would be manufactured using a metal that will rust, and that isn't safe for contact with water.
It could be a copper or brass fitting, but Ive not seen "silver" copper or brass.

I also find it strange that this tank has a 1" fitting... most accumulators that I've seen have smaller fittings.

Oh well, what can you do for $60 (yup, $60 CAD for this 9.2 gallon accumulator tank)

I really am just being over cautious, I know, But I am really concerned about that flange plate and its "origins" lol.

[ct-death]

This may help a bit: http://www.plumbingworld.com/pipefittings_stainless.html

Stainles is the obvious choice as it is often used in sanitation, water storage and in kicthens.

Another possability (albeit remote) is nickel, but i would not think that is the the case.

Take a look at the link, it should help you price things out for your local plumbing store, but I would encourage you to go to a plumbing store and discuss your fitting (bit the fitting in to them too!). They will provide some great information. Then you cna buy the product you need elsewhere (plumbing stores are outlandishly priced!)

Good luck

[Squawkbert]

RO water is actually fairly aggressive in terms of corrosion potential (it isn't nitric acid, but it's a lot worse than people generally expect it to be).

316 Stainless steel is the way to go wherever you must have metal.
If possible, use a stout PEEK tubing with 316 SS swage type compression fittings wherever stuff has to be joined after the water has been through the system.

Before the filter it doesn't matter as much, but if you're adding a bunch of different metal ions and complexes, your filters & RO membrane will not last as long.

[TKOS]

Yes, not all stainlessis created equal. If it is cheap then it probably isn't great quality and will rust eventually.

Corrosion potential is one thing but metal will still need a salt to corrode.

[DarkSoul]

Well as far as a fitting, I think i know what I need.

a 1" NPTF elbow, and a reducing bushing (or two).
I have found these on one particular aquarium site, and it would allow me to plumb it in just as I want it, But again, it comes back to this darn flange on the tank itself.

Sure the area of metal coming in contact with the water may only be about 1" (round) by about 1" long, but if that metal isnt a food grade metal, then it is going to corrode (or will it? This RO contains NOTHING, No salts, no minerals, nothing. it is SO pure, drinking it causes dehydration)

Now, I can generally identify most metals, by looking at them, and I have to be honest here, Looking at this flange, I want to say that it is just plain, metal/steel/etc.
A ferrous metal, which will corrode (or even rust) over time.

I seriously am considering unbolting this flange, and taking it to the "local" plastic welding/fabrication shop and having them make me up a plastic flange to fit inplace of the metal one.

In this process, they would also be able to convert that 1" nipple on the flange, to something more easily workable, such as a 1/4" NPTF fitting, which would allow me to very easily stick a 1/4" JG swivel elbow, and plug my tubing right into it, without much effort.

again though, this ends up costing money, so as far as that goes, no matter what I do, I dont be saving anything :)

would there be anyway to determine what sort of metal this flange is made from?

A couple of ways I could think of, would be;

1.) Use a magnet, if it sticks, its ferrous, and will likely rust or corrode in ways that will contaminate my water.

2.) try and "shave" a small fragment of the metal, and burn it at an extremely high temperature and see what colour the flame burns.
Copper would cause a green flame, Regular metal would produce the typical red/orange flame, and i forget what colour brass burns.

But once again, they almost don't seem like fiesable ideas.

[ct-death]

Can you offer the products name/model or post an image of the fitting?

You "typical" metals used by drinking water are (there a bunch of new alloys out there and of course coatings applied to who knows what): Copper, Brass, Nickel, Stainless and steel (Galvinized Zinc). Black Iron is not used w/ drinking water. These are your typical choices, but I have seen different alloys used in certain situations typically w/ pressure.

Regardless I think it's a safe bet that the fitting that came with you $60 tank does not pass your quality standards - especially if it IS stainless or a steel-alloy. Also, if it is coating, taking a shaving is a bad idea (it will ruin any corrosion protection it had).

Also judging from you response (it is just plain steel...) I would assume Galvy atm...?

EDIT: GratZ! :D

[DarkSoul]

It would seem now that I have accidentally stumbled on to the answer to my question of what metal this is.

When i minimized my page, I had open a page of pipe fittings that I didn't get a chance to look at lastnight.
Upon looking closely at these 304 Stainless fittings, I noticed that the metal looks identical in appearence to the flange plate on my tank.

It is (presumably) 304 Stainless steel.

I managed to dig up this information about 304 SS on the following page
http://www.azom.com/Details.asp?ArticleID=965

Chemical Formula

Fe, <0.08% C, 17.5-20% Cr, 8-11% Ni, <2% Mn, <1% Si, <0.045% P, <0.03% S

Corrosion Resistance

Excellent in a wide range of atmospheric environments and many corrosive media. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C. Considered resistant to potable water with up to about 200mg/L chlorides at ambient temperatures, reducing to about 150mg/L at 60°C.


I would have to say, based on the information on that page, that this "304 SS" is suitable for this purpose.

A few good rinses with water should suffice.

Now I need to buy a tire pressure gauge to see what the tank is pressurized to :)

[DarkSoul]

Can you offer the products name/model or post an image of the fitting?

You "typical" metals used by drinking water are (there a bunch of new alloys out there and of course coatings applied to who knows what): Copper, Brass, Nickel, Stainless and steel (Galvinized Zinc). Black Iron is not used w/ drinking water. These are your typical choices, but I have seen different alloys used in certain situations typically w/ pressure.

Regardless I think it's a safe bet that the fitting that came with you $60 tank does not pass your quality standards - especially if it IS stainless or a steel-alloy. Also, if it is coating, taking a shaving is a bad idea (it will ruin any corrosion protection it had).

Also judging from you response (it is just plain steel...) I would assume Galvy atm...?

EDIT: GratZ! :D


I do not know of any brand name... nothing is on this tank.
Its blue, has 3 legs. I purchased it at princess auto, for those who know the store.
It is likely either overstock, or surplus from somewhere else and if it isnt, then it is Princess Auto's house brand "Power Fist"..... but they never leave off a label, so this isnt likely.
But it was more expensive previously, so dont use the budget price as a guide so much... I think it was originally like $99, which is what I usually see these things selling for.

I am unsure about the flange being 304 stainless, but it seems likely, as that seems to be a fairly cheap grade of stainless, used when making potable water systems and the like, and being the tank came from a surplus store of sorts it would be the type of product to use a chaper grade of metal suited for the application at hand.

I think i will call plasco and see if they could possibly manufacture this flange out of plastic, and if so how much.
Just because im curious.... If this is 304 SS, I think it should be OK.

unless someone else has other ideas.

[DarkSoul]

I had an idea, and what i think i might do, is use some of the marine epoxy i puirchased for my background, to seal this metal.
this way no metal will be touching the water at all.

simple problem, simple soloution :)

[Star_Rider]

sealing the metal seems easy to do but in reality may not work..if this is a flange.hinge etc..it is attached to the box..no?
there is chance that the seal will break when attaching the flange back in place..also if there is any moving parts..you will inevitably wear thru the seal.

I'm curious why you need this water to be so pure.

[DarkSoul]

this is an accumulator tank..... not a box, and has no moving parts.

sealing the metal will work in this instance.

And the water is so pure.... simply because I have the means to do so. :)

[kw0me]

the powder you were talking about on the rubber would be like talcum powder its used to stop the rubber breaking down when dry.

[DarkSoul]

ok, So I got some pics of this water tank..... My GF has aptly named it "Oswald the Octopus" .... and those of you with children will probably know why..... she looked at me rather strangely when I began taking pictures of oswalds private regions and then further, his insides..... actually it sort of creeped me out for a bit there too lol.

The tank itself. 9.2 gallons is its listed size. Assuming an approx. difference of 2 gallons based on other tanks I've seen, it should hold about gallons. I know nothing about it, including its max rated pressure, However I assume its 80 PSI as the rest of our water supply is.
I was unable to verify its precharged pressure before I discharged it.
http://theinterstellardestroyers.com/DSCF2040.JPG

Here is the metal flange which has been the topic of much discussion in this post :) You can see it is rather large, and secures the bladder.
I believe it is a 1" pipe thread.
http://theinterstellardestroyers.com/DSCF2041.JPG
http://theinterstellardestroyers.com/DSCF2042.JPG

The flange removed.
http://theinterstellardestroyers.com/DSCF2047.JPG

A peek inside the tank itself. Are most accumulator tanks built this way? with a large bladder inside a tank like this? Or are they lined inside the tank itself?
The metal tank itself looks a little rusty, so I may shoot some rust paint in there before I actually use it.
Also, will this bladder expand? or will it remain its current size under pressure and full of water? it seems alot smaller than the actual tank itself, and not like it will hold even 7 gallons of water.
http://theinterstellardestroyers.com/DSCF2048.JPG
http://theinterstellardestroyers.com/DSCF2050.JPG
http://theinterstellardestroyers.com/DSCF2052.JPG

A look inside the bladder... a little powdery, but generally good condition, just needs a real good flushing before use.
http://theinterstellardestroyers.com/DSCF2056.JPG

Lastly, the air valve, to rpessurize the tank.... nothing really more to say about this device except that its covered with a nice little cap :D
http://theinterstellardestroyers.com/DSCF2057.JPG