Examining possible solutions to issue of sulfur smell from Perlick 650ss faucets

BrunDog said:

By the way, there is no way that Perlick does not know this is an issue. If they recommend avoiding low pH beer, they know about the problem. That's just lousy customer service and I say we leverage this forum to get them to own up and remedy the problem. I certainly appreciate your willingness to experiment, but that's not something you should need to do for a "quality" product you paid quality dollars for.

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+1 to this. I too think Perlick knows about the problem and I think these experiments probably won't tell them much that they don't already know. But I appreciate the desire of the OP to get to the root of the problem.

I too work for a mfr and one of the biggest factors in how we respond to a problem is how many complaints we've received. 1 complaint = probably a fluke. 100 complaints = we need to do something about it.

I have 1 650ss with no sulfur smell issues. But if it did, I would demand a replacement or repair kit from Perlick. I know it can be time consuming and frustrating getting through to the right person, but I wouldn't give up. Good luck.

Dont start a new thread. There are already other threads.

My lot codes are A0115G and A0215G. Looking at other posts I'm inclined to think the numbers are MMYY too.

The increasing sulfur smell with a starsan makes me nervous. Agrazela (and anyone else with a knowledge of chemistry and/or metallurgy) do you feel comfortable that nothing unwanted is leaching into our beer? In my mind food grade stainless and components should NOT be having this issue.

CascadeOK said:

My lot codes are A0115G and A0215G. Looking at other posts I'm inclined to think the numbers are MMYY too.

The increasing sulfur smell with a starsan makes me nervous. Agrazela (and anyone else with a knowledge of chemistry and/or metallurgy) do you feel comfortable that nothing unwanted is leaching into our beer? In my mind food grade stainless and components should NOT be having this issue.

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From my reading of items linked earlier in this thread, my theory is that there is sulfur deposited on the surfaces of these (suspected) 303ss parts, likely from improper passivation procedure (and that is looking possibly like a lot-to-lot issue). I think (hope!) all that needs to happen is that this surface sulfur needs to be got rid of (hopefully through simple acid dip), and THEN they'll be fit for service.

BrunDog said:

Dont start a new thread. There are already other threads.

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I'll just pester people on existing threads for their lot codes.

-TH- said:

+1 to this. I too think Perlick knows about the problem and I think these experiments probably won't tell them much that they don't already know. But I appreciate the desire of the OP to get to the root of the problem.

I too work for a mfr and one of the biggest factors in how we respond to a problem is how many complaints we've received. 1 complaint = probably a fluke. 100 complaints = we need to do something about it.

I have 1 650ss with no sulfur smell issues. But if it did, I would demand a replacement or repair kit from Perlick. I know it can be time consuming and frustrating getting through to the right person, but I wouldn't give up. Good luck.

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I agree Perlick must know. If AIB is to be believed (and I believe them), it's PROVEN that they've known of an issue for at least 9 months. Their denial of my issue on the phone to me is why I'm not going to let up or give any benefit of the doubt.

And what they probably know is that a fix would involve all three of these parts (handle lever, compensator, and barrel of the flow control handle device) re-machined out of 304ss (or re-made of 303ss with proper passivation) and decided that ignoring and/or denying the problem is hella cheaper (in the short term, anyway) than fixing it. And that developing some sort of "DIY fix" for owners to do is an admission of a problem, so that's out, too.

AND if I may further speculate...they probably decided that since these faucets were going to be designed specifically for beer (not wine or cider), why not save a few pennies per unit and use 303ss for these parts? Maybe further cheap out on manufacturing and not specify proper passivation (or go with factories that cut corners)? Except that they forgot about low-pH beers (sours, hefe's, etc.). And also it turns out that even "normal" pH beers (APA, IPA, etc.) are causing issues, at least with some (lots of) 650ss faucets, like the ones I have.

BTW -TH-, what's your lot code?

My experience with star san and nitrile rubber matches the sulfur (rotten egg) aroma you've been experiencing.

Place 1 nitrile rubber glove in a glass jar (like the blue one you're wearing in the photo) and spray some star san on it. Wait like 5 seconds and take a whiff (you'll smell it very well). Now seal, wait 5 minutes and take a whiff (it might knock you out ).

The most common o-ring material is Buna-N (the 'N' standing for nitrile), and I'm assuming that's what's used in perlicks. Those flow control seem to have a lot of o-rings/nitrile in them. Couple those o-rings with star san (or perhaps just very low pH solution), and you get rotten eggs.

In addition, it's possible that you've been unknowingly contaminating your experiments by wearing the gloves to do your work. Next time try using metal tongs or forceps instead - just to see.

A possible solution to the perlick tap issue: How about buying some silicone replacement o-rings and see if you still get the rotten egg smell. A test at least.

agrazela said:

BTW -TH-, what's your lot code?

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I will check tonight at home and post it. I should mention that mine is fairly new and I've only run one beer through it so far (IPA).

OK so next morning, if I had to rank the strength of sulfur smell coming off the beakers of the three parts being soaked in 1:1 Star San anlog : distilled water from strongest to weakest, it would be:

Compensator, closely followed by handle lever, and flow control barrel a distant third. (But in all three cases, VERY definitely sulfur-y)

The parts do not appear to be damaged or discolored in any way. I rinsed the parts in distilled water, and laid them out to air dry for the rest of the day (Pic 08) in case the chromium needs to re-oxidize. If there is still any sulfur odor on the rinsed parts, it's very, very faint. Or I can't tell because I'm getting nose-blind to sulfur at the moment. I'll sniff them again periodically throughout the day and report if I get anything.

All the other parts in the dilute Star San analog I also rinsed in distilled water and laid out to air dry.

I think this faucet may be ready to be re-assemble and put back into service to test whether it is fixed...that of course will be monitored over days (or weeks).

I would normally be inclined to not believe the stainless parts are the issue, but if your acid soaks produce sulfur, then sure enough they are. The practical question is... Can you get the sulfur out enough to be below the smell and taste threshold?

BrunDog said:

I would normally be inclined to not believe the stainless parts are the issue, but if your acid soaks produce sulfur, then sure enough they are.

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Not if he's using a nitrile-gloved hand that comes into contact with the acid solution. See my explanation below.

stpug said:

My experience with star san and nitrile rubber matches the sulfur (rotten egg) aroma you've been experiencing.

Place 1 nitrile rubber glove in a glass jar (like the blue one you're wearing in the photo) and spray some star san on it. Wait like 5 seconds and take a whiff (you'll smell it very well). Now seal, wait 5 minutes and take a whiff (it might knock you out ).

The most common o-ring material is Buna-N (the 'N' standing for nitrile), and I'm assuming that's what's used in perlicks. Those flow control seem to have a lot of o-rings/nitrile in them. Couple those o-rings with star san (or perhaps just very low pH solution), and you get rotten eggs.

In addition, it's possible that you've been unknowingly contaminating your experiments by wearing the gloves to do your work. Next time try using metal tongs or forceps instead - just to see.

A possible solution to the perlick tap issue: How about buying some silicone replacement o-rings and see if you still get the rotten egg smell. A test at least.

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I've tested four different colors and brands of nitrile gloves. They all produce the same sulfuric, rotten-egg aroma.

stpug said:

My experience with star san and nitrile rubber matches the sulfur (rotten egg) aroma you've been experiencing.

Place 1 nitrile rubber glove in a glass jar (like the blue one you're wearing in the photo) and spray some star san on it. Wait like 5 seconds and take a whiff (you'll smell it very well). Now seal, wait 5 minutes and take a whiff (it might knock you out ).

The most common o-ring material is Buna-N (the 'N' standing for nitrile), and I'm assuming that's what's used in perlicks. Those flow control seem to have a lot of o-rings/nitrile in them. Couple those o-rings with star san (or perhaps just very low pH solution), and you get rotten eggs.

In addition, it's possible that you've been unknowingly contaminating your experiments by wearing the gloves to do your work. Next time try using metal tongs or forceps instead - just to see.

A possible solution to the perlick tap issue: How about buying some silicone replacement o-rings and see if you still get the rotten egg smell. A test at least.

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Never having used Star San before (nor dipped my gloved hands in phosphoric acid), I did not know about that issue with nitrile. Ironically, I donned the gloves because I was originally using bare hands, and my hands were starting to stink so bad from sulfur I needed a barrier between my nose and hands. Additional irony: I did not use stainless tongs for fear of contaminating my experiment with an unknown grade of tongs.

Quick web search turned up this thread:
https://www.homebrewtalk.com/showthread.php?t=175177

Speculation there that the smell either comes from the reaction between phosphoric and excess sulfur-containing crosslinker in the nitrile, or from something going on with the sulfur in the dodecylbenzenesulfonic acid in the Star San.

Luckily I can separate and test: 1% phosphoric acid in distilled, vs 1% Micro 90 in distilled, vs 2% of my Star San analog in distilled (Pic09). And if any of you guys know that Saran Wrap has sulfur in it, keep it to yourselves.

After a 10 minute soak, sure enough the smell of sulfur from the phosphoric acid and from the Star San analog, but not from the Micro 90 alone. So it seems that the acid is messing with something in the glove, I suppose excess cross linker (I guess I'll look that up later).

Being curious, I then did 1% citric acid in distilled, and after 10 minutes, yes, sulfur.

I suppose if I was writing a paper for publication, I'd have to start over. And any further testing will be nitrile-glove-free.

But I can tell you, the strength of the sulfur smell coming off these glove soaks is like a breath of sweet, fresh air compared to what's been emanating from these beakers containing the suspect parts and the concentrated Star San analog. There is absolutely no doubt whatsoever in my mind that these faucet parts are the source of the sulfur in my beer.

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Interesting thought about the buna-n O-rings, though. I guess for now I'm gonna have to hope that however much "excess" cross-linker they put into those is eliminated by the standard dilution Star San analog dip. Or that O-rings are made with a different cross-linker. Or that O-rings don't use excess sulfur. I mean hey, all those Perlick forward-seal faucets use the same seals for the various parts of the handle lever ball, and presumably they're buna-n, and again we're not seeing any complaints about 630ss.

Guess I've really got to put some research into this cross-linker in nitrile thing now.

This could be one of the most interesting experiment threads ever produced on HBT!

Lot #A0515G. No sulfur issues.

Update on Treatment Test 1, soaking all parts in dilute Star San analog and the three suspect parts (handle lever, compensator, flow control "barrel") in concentrated (1:1) Star San analog, on the first of three 650ss faucets (lot code A0915G):

Re-installed in keezer Friday evening 3/11/16, hooked up to an American Pale Ale using a new length of EJ Barrier tubing after the tubing/QD assembly had sanitizer pushed through it from a pressurized keg.

Let sit overnight with flow control at about the "halfway" position. Next morning (Sat), first draw (about two ounces or so) had a faint smell of sulfur, immediately subsequent pour does not. Next morning (Sun), same story.

This smell is GREATLY diminished from what it was originally, but it is not gone. I will check again Mon morning before work (for science!).

My theory is that I got some portion of the residual sulfur off, but not all of it. I think next step is to take the three suspect parts and subject them to another concentrated Star San soak (or two, or three) to see if I can get it all.

Call Perlick and tell them to make it right. It's a known, documented problem.

Your experiments are cool but at some point they need to be accountable for inferior quality.

BrunDog said:

Call Perlick and tell them to make it right. It's a known, documented problem.

Your experiments are cool but at some point they need to be accountable for inferior quality.

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I did call inquiring about the problem (post 12). I got a fistful of denial. If I don't find a fix I will either demand a fix from Perlick or return them.

Accountability will, at minimum, be expressed in whether or not I decide to buy Perlick products in future. That and getting the word out about my experience is about all I can really expect to do as a consumer.

I am surprised how few individuals have posted in this thread. Either there aren't as many people experiencing this issue as I believed, or most folks have already given up on these faucets.

You beat me to this topic by just a couple days. I actually had it all written up and have been waiting to make sure the sulfur smell didn't come back before posting. I only came across this thread when I was making some edits in preparation for posting and trying to find a reference from another thread. I don't want to re-edit what I've already done so here it is, there is some duplicate information from earlier in this thread :

Recently a friend of mine purchased some brand new Perlick 650SS flow control taps. Unfortunately, it seems that some 650SS taps are prone to causing a sulfur odour when used with low pH beer or cider. Numerous complaints can be found on this forum and others, AIH even posts a warning on their 650SS page. In our experience, the sulfur odour happens after the beverage has been sitting in the line for at least an hour; after a pour or two it will go away until it is left stagnant for a while. After some research and experimentation, I'm confident that we've determined the source of the sulfur smell and how to fix it. There is a chance that the theories presented below are not entirely correct, but the procedure did fix the sulfur issue for us.

Source of the sulfur
The 650SS is very similar to the design of the 630SS, with the addition of flow control. However, these flow control parts are (probably) fabricated from 303 stainless instead of 304 stainless. 303 was likely chosen since it is easier to machine – a useful property for small, intricate flow control parts. Why is it easier to machine? Because of sulfur additions in the steel (also phosphorus, but that isn't important here), which allow the tool to slide more easily over the surface and promote clean shearing of the steel. The sulfur/rotten egg smell comes from residual elemental sulfur that remains on/in the surface. The sulfur should have been cleaned off before the steel was passivated. Passivation is a process which builds up a protective oxide layer on top of the just-cleaned stainless.

303 and other 'free-machining' stainless steels need a slightly different procedure from the standard passivation in order to remove residual surface sulfur – essentially just a pre- and post-soak in alkaline solution, preferably sodium hydroxide. ASTM A967 mentions this the in appendix (paragraph X1.3.3), but does not specify a procedure. Basically, the acid used for passivating the stainless dissolves the MnS inclusions, leaving behind elemental sulfur in the resulting pits which is not removed by typical post-passivation cleaning. Check out this paper which provides a more thorough discussion of what is happening.

Why does Perlick let this happen?
Since this problem does not occur consistently with all 650SS taps, I have a couple guesses as to the cause:

1. Perlick has multiple vendors/factories doing their cleaning/passivation, some who know how to treat 303SS and some who do not.
2. Their passivation treatment method is borderline ok, taking away most of the residual sulfur, but certain batches of 303 have higher sulfur content resulting in leftover sulfur on the final product .

These are simply my guesses and I do not have any concrete knowledge of Perlick's actual operating practices or materials used, just my own experiments which have a very small sample size. I emailed Perlick with the information in this post, but have not received a response from them. I will update this post if I do.

Experimentation
Since we had two 650SS taps, we wanted to test whether the NaOH soak was sufficient to correct the problem, or if a full cleaning and passivation treatment was required. One of the taps only underwent a NaOH soak (5 wt% @ 70°C for 30min). For the other tap we performed the NaOH soak, followed by passivation in citric acid (as per ASTM A967 Citric I, 10 wt% citric acid @ 60-70°C for 1 hr), followed by another NaOH soak same as before. Citric acid was used since most homebrewers would not (and probably should not&#8230 have access to the nitric acid and sodium dichromate bath traditionally specified by ASTM A967.

We've been using the taps on a cider (pH unknown – it’s all gone now) and berliner weisse (pH 3.3) for the past month or so and have not had the sulfur smell return on either tap. There may have been a couple times where the taps were not used for several days and they was a hint of sulfur, but I'm unsure whether this was just me being paranoid. It was subtle enough that I doubt I would have noticed it if I wasn't actively looking for it. Therefore, I believe a single alkaline soak treatment is enough to solve the problem.

How to remove the sulfur
The following procedure details the process to desulfurize your Perlick 650SS flow control taps. You should only need to do this once and the sulfur will be permanently removed from your taps.

CAUTION: Sodium hydroxide, and to a lesser extent, citric acid, are hazardous chemicals which should be treated with greater care than your standard brewery chemicals such as PBW or starsan. This website provides a reasonable overview of the hazards. Always read the MSDS and take appropriate safety precautions before using highly caustic or acidic chemicals.

Follow this procedure at your own risk, I am not responsible for your safety.

You may be able to find both sodium hydroxide and citric acid at your local homebrew store. However, I found it was 1/10 the price at a local DIY soapmaking store, and I could buy it dry instead of a premixed liquid form. Hardware stores may also stock it.

1. Completely disassemble the Perlick 650SS tap. Don’t worry about removing the o-rings; they are Buna-N/Nitrile, which is compatible with all of the chemicals being used.
2. Separate the 303SS parts that need to be cleaned, rinse them in hot water, and set aside. The 303SS parts are handle lever (item 5A), flow compensator (item 9) and/or the flow control lever shaft (item 11) in the diagram on page 2 of this link. I’m not entirely sure if all these parts are 303 but this procedure isn’t going to damage anything if they aren't. You could probably throw the whole tap in the bath, but I was worried about etching the polished finish on the outside of the tap. After further research this probably isn’t a concern, but proceed at your own risk.
3. Prepare a 5 wt% NaOH (sodium hydroxide) solution in a stainless steel or borosilicate glass container large enough to fully submerge the parts. My starter flask worked well for this. This can be done by mixing 5g of dry NaOH per 100 mL of water. ALWAYS add the NaOH slowly to cold water, not the other way around! Dissolving NaOH is an exothermic reaction (gives off heat) and may spatter if water is added to the NaOH. Distilled water is preferred, especially if your tap water contains a lot of minerals.
4. Heat the solution to 70°C. Make sure you have adequate ventilation in the area.
5. Place the parts in the hot NaOH solution and soak for 30 minutes, maintaining temperature.
6. Rinse parts thoroughly in water.
7. Rinse parts in isopropyl alcohol. I'm unsure whether this step is necessary, but Shen mentions it in their paper as reducing the surface residue so I don't think it hurts.
8. Rinse parts thoroughly in water and allow to dry.
9. Smell or taste the parts. If you can still detect sulfur, something may have gone wrong. You can try installing the taps and using them, or try the full alkaline-acid-alkaline passivation treatment with citric acid. To perform full alkaline-acid-alkaline passivation treatment, proceed the same as above, completing step 6. Then prepare a 10 wt% citric acid solution in the same manner as the NaOH solution, using a ratio of 10g/100mL. Heat up the citric acid solution to ~60-70°F and soak for 1 hour. After the citric acid soak, rinse the parts in water, and continue again at step 3, repeating the NaOH wash (steps 3-9).

Let me know if you have any questions!

References:
ASTM A967 - Standard Specification for the Chemical Passivation of Stainless Steels
The Cleaning of 303 Stainless Steels (T.H. Shen, 2004))
Carpenter Technology - Passivating and Electropolishing Stainless Steel Parts


Onto this thread:
Based on my write-up above, I think you should try the NaOH soak again, possibly for longer. Also, it sounds like you just soaked the levers last time? You should soak all three parts you show in pic08

I hadn't come across the information stpug raised regarding the reaction of buna-N/nitrile with starsan. I wouldn't worry about it unless nitrile gives off sulfur in all acidic solutions (more specifically beer/cider/wine/etc.). However, I don't have much background with polymers so I could be missing something. To back up your point that the acidic starsan is releasing sulfur from the stainless parts, I did notice a strong sulfur smell when performing the citric acid soak and I was not using nitrile gloves (though I probably should have used some for safety).

^^^ Hell of a nice first post! Very good to know you fixed yours, I knew there had to be a way.

Now of course I want to know, what are the lot codes on your friend's faucets?

I have not yet done NaOH soak, the soak I did of the three suspect parts was in a concentrated Star San analog (phosphoric acid).

I have two more 650ss faucets to treat. Full-on passivation just as described in the paper we've both linked is one of the treatments I'm planning to try, and now you've given me a third (and fairly simple) option to try, just soaking the three suspect parts in hot NaOH.

Ha, thanks, I rarely post on forums.

Both of his faucets are lot code A0815G.

agrazela said:

SO, I did an experiment. I pulled the levers from my three 650ss faucets. And they did smell strongly like rotten eggs. I took a cue from that gov’t paper where they suggest that improperly passivated 303 stainless can be remedied by soaking the parts in 5% NaOH at 70°C for 30 minutes, followed by a detergent wash, a water rinse, and a wipe with isopropyl alcohol. I did that procedure in the lab, reinstalled the levers and…

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You didn't do an NaOH soak? Your above statement in the OP seems to disagree with that...

sctcts said:

Ha, thanks, I rarely post on forums.

Both of his faucets are lot code A0815G.



You didn't do an NaOH soak? Your above statement in the OP seems to disagree with that...

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So correct, I totally forgot that I did that. Guess I'll do it again.

EDIT: correct again, I did the NaOH soak on only the handle levers, not the other two parts.

Great info! Thanks for all the hard work that went into gathering this info.

Are you saying if an alkaline-acid-alkaline passivization treatment was needed we'd have gone through Step 6, smelled or tasted sulfur,
so we do a 1 hour soak in 60-70°C 10 wt% citric acid after step 6, then

"after the citric acid soak, rinse the parts in water, and continue again at step 3"

So we go back and do another 5 wt% NaOH soak (complete the original list steps 3 - 9 again)?

I'd rather Perlick replace my faucets but I'm getting limited use out of them now so if I have to I'll try the DIY method. Kinda hoping Perlicks company moto "Quality & Innovation that Inspires" is something they live by, not marketing BS. We shall see

CascadeOK said:

So we go back and do another 5 wt% NaOH soak (complete the original list steps 3 - 9 again)?

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That's correct. I just reworded my previous post to make it clearer.

I swapped a beer from my 630ss to my 650ss because it was extra foamy and all of a sudden I get nothing but sulfur smell (rotten egg) out of the tap. pH 4.43 @ 40°F (my kegerator temp) on a 3.7% ABV ordinary bitter. I didn't have any smell problems on the 630ss and googling it brought up this thread. I'll post my lot codes tonight. The faucets are all brand new bought from MoreBeer right after Christmas the 650ss has had and APA (pH 4.80) and a vienna (4.59 pH) poured though it with no previous issues. Looks like somewhere between pH 4.59 (no sulfur) and 4.43 (eggs galore) my faucet is having trouble. I don't think 4.43 is very acidic though for beer is it? Casual googling came up with a few references of 3.8-4.5 for "normal" beer pH (guess that's at room temp?).

I do not have a sulfur problem, both my faucets are A0215G, been in service since November '15, sometimes the beer sits for 3 weeks and no issues (I had bronchitis). I did clean with PBW and then run Acid Blend #6 in a 2oz/Gallon ratio when I installed them.

On to Treatment Test 2: Soaking only the suspect parts in hot NaOH.

Made a 5% solution of NaOH in distilled water (Pic10), came out to pH 13.30. Only the three suspect parts (handle lever, compensator, flow control shaft; Pic11) went into that, the rest of the parts got a soak in dilute Star San analog.

(I did remove the o-ring seals from the flow control shaft because I wanted to make sure all surfaces of that shaft were exposed to the NaOH solution, and because nitrile rates as only “fair” compatibility with concentrated NaOH according to the rubber chemical compatibility charts)

Suspect parts soaked in 5% NaOH for 30 minutes at ~70°C (Pic12)—using stainless steel tongs this time, no gloves!

No sulfury odor came off of this solution. Perhaps this is because sulfur reacts with hot concentrated M+ hydroxide solution to form M+ sulfide and M+ thiosulfate salts:
http://www.webelements.com/sulfur/chemistry.html

Which are highly soluble:
https://en.wikipedia.org/wiki/Sodium_sulfide
https://en.wikipedia.org/wiki/Sodium_thiosulfate

(And it takes an acidic reaction with the sulfide salt to produce the H2S hydrogen sulfide gas that has that “rotten egg” smell)

Then parts were rinsed in distilled water, then rinsed in 70% isopropyl alcohol. (As sctcts has said, unsure if the alcohol is necessary, but I’ve got it, and it’s basically just concentrated rubbing alcohol), then laid out to air dry. I can't smell any obvious sulfur now on these parts.

Note: as I removed the rest of the parts from the Star San analog soak, the flow control handle (Pic13) definitely had a sulfur smell coming off of it. But that part doesn't touch beer.

Will reassemble this faucet, put back into service, and report.

.

Addendum (again, forum not allowing me to edit)

As these parts were air-drying, I can swear I smelled sulfur on my SS shank, too. Well, it could be made from improperly-passivated 303ss also. So I repeated the Treatment 2 process on this shank (minus the lock ring, collar and coupler) and on the flow control handle (because what the hell, it's already disassembled and it's just sitting there).

Now, since somebody had to do it, on my third 650ss faucet I ran Treatment Test 3: full alkaline / acid / alkaline passivation.

(This is the “if this doesn’t work, I may be all out of ideas” option)

Soaked all stainless parts (including shank and tailpiece for completeness) in 5% NaOH for 30 minutes at ~70°C (Pic14). Rinsed in distilled water, then soaked in 10% citric acid for 30minutes at ~65°C (Pic15).

(Note that I got a lot of sulfur odor off of the citric acid soak. This does not bode well for previous Treatment 2, as maybe that single NaOH soak alone is not enough to get all the sulfur?)

Rinsed again in distilled water, followed by another 30 minutes soak in fresh 5% NaOH at ~70°C. Then rinsed in distilled water, then rinsed in 70% isopropyl alcohol, then laid out to air dry.

All the non-stainless, chrome-plated brass parts (faucet bonnets and bearing cup, shank's coupler and collar, etc.) and the seals got a soak in dilute Star San analog, then laid out to dry.

There does not appear to be any discoloration or damage to the shiny exterior of the faucet (Pic16).

Will also put this faucet back into service and report.

Thanks for documenting your process agrazela, I'm terrible at remembering to take pictures as I go.

agrazela said:

(I did remove the o-ring seals from the flow control shaft because I wanted to make sure all surfaces of that shaft were exposed to the NaOH solution, and because nitrile rates as only “fair” compatibility with concentrated NaOH according to the rubber chemical compatibility charts)

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All the information I looked at shows Buna-N as fully compatible with NaOH, at least at concentrations of 20% and under.
http://www.coleparmer.ca/Chemical-Resistance
http://www.efunda.com/designstandards/oring/oring_chemical.cfm?sm=none&sc=sodium%20hydroxide
http://www.quickcutgasket.com/pdf/Chemical-Resistance-Chart.pdf

You do make a good point about making sure the NaOH could get all surfaces of the shaft, but I figured that if the NaOH didn't reach a spot, the beer wasn't going to reach it either. And I didn't want to risk damaging the o-rings trying to get them off.

agrazela said:

Soaked all stainless parts (including shank and tailpiece for completeness) in 5% NaOH for 30 minutes at ~70°C (Pic14). Rinsed in distilled water, then soaked in 10% citric acid for 30minutes at ~65°C (Pic15).

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I used a 60 minute acid soak, but 30 minutes should be sufficient. The actual requirement for ASTM 967 Citric I is only a minimum of 4 min at a 60-70°C, 4-10% citric acid, so you're well above this.

agrazela said:

There does not appear to be any discoloration or damage to the shiny exterior of the faucet (Pic16).

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Nice to see confirmation that the outside of the faucet doesn't etch in the acid.

agrazela said:

Pic15

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Your setup with the clamp looks much more scientific than mine did haha. For those who do not have a stand like agrazela used, a vegetable steamer works well to keep your vessel suspended off the bottom and away from the direct heat. It's a good idea to heat the NaOH or citric acid in a water bath like agrazela did to maintain a more stable temperature.

Update my smelly faucet is lot# A0515G