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Caustic (sodium hydroxide) vs alkaline noncaustic (percarbonate + metasilicate)

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  • Caustic (sodium hydroxide) vs alkaline noncaustic (percarbonate + metasilicate)

    We're scaling up production and I'm in the process of reviewing cleaning procedures in our brewery. So far we have been using a PBW like cleaner (sodium percarbonate and sodium metasilicate) in hot solution for primary cleaning of soil and debris but most info about CIP mentions use of caustic sodium hydroxide solutions before rinse and acid wash and sanitizing. Is there a reason to prefer hydroxide to percarbonate? On the surface, it looks that their cleaning principles are different, since NaOH acts by being an alkali while percarbonate is an oxidant.

    Apart from the reaction with carbon dioxide from carbonation, I'm worried about corrosion issues. How much contact time for a given temperature is safe for stainless steel?

  • #2
    In my experience NaOH is preferred in most applications with 300 series stainless. Most use between 0.5%-2% solution by volume (dependent on brands, usually at around 45%+/- actual NaOH) at up to 165*F (74*C). The sodium percarbonate and metasilicate is particularly useful for applications that contain aluminum. They are usually around 20-30% actual compound.

    Yes they have slightly different principles, but you can also add hydrogen peroxide to your NaOH reacting into Sodium Percarbonate. The cycle time for any CIP will be dependent on solids load, concentration, temperature, and mechanical action (spray ball). Usually 20-30 mins is sufficient however you should verify your procedures by lab periodically, IMHO. Rinse until pH neutral, then next step.

    I prefer NaOH (ideally with some KOH in it) as it just plains works better. I can use less chemicals, I can use a hotter temperature, and it is easy to measure/dispense. If I find a need for more aggressive action, I can just add some H2O2. I keep some Metasilicate on hand for any aluminum applications, and as an alternate back up.

    You will not have corrosion issues arise from NaOH or KOH. Basically the temperatures and concentrations we are using would be well below the threshold of concern. You can use pure NaOH (maximum possible saturation) up to 80*C without risking the integrity of 304/316 steels. Avoid heating any chlorinated products over 60*C for any reason (I just don't use them).

    I recommend Dana Johnson from Birko Corp, but Loeffler is a great resource also. I believe Dana wrote an article on brewery CIP in the July/August 2017 issue of New Brewer where he outlines an alternative method that I have used for years.


    • #3
      NaOH is a dangerous chemical...

      Likely the one that causes the most accidents in the world. If used correctly with lots of PPE, then you should be OK. For me, I'd rather use something like Bru-r-eze or PBW. Much less dangerous. And still quite effective. And I don't like high temperature CIP schedules. They stress welds on tanks. Especially those that don't have proper weld penetration. Like most cheap stuff. Up to you, but I'd give the alternatives to NaOH a try. If they work well for you, then it's much safer.
      Phillip Kelm--Palau Brewing Company Manager--


      • #4
        I also prefer caustic based detergents to metasilicate, but accept horses for courses.

        Whatever you use, DON'T use raw caustic. It should contain a variety of additives such as wetting agents, rinsing agents, mineral dissolving agents. Even if you are in an area with extremely soft / low mineral content water, you must use additive containing detergent as the mineral salts in beer and unless fully demineralised, the tiny amounts of minerals in the rinse water can still build up - I saw over 1 cm of hard water scale on FVs and MVs at one brewery where they had not used formulated detergents. If using acid detergent washes to help prevent scale build up, then these also need to be formulated to help wetting and prevent bacterial build up, particularly if you are re-using the acid and merely topping up to strength normally.


        • #5
          Originally posted by gitchegumee View Post
          Likely the one that causes the most accidents in the world. If used correctly with lots of PPE, then you should be OK.
          I will concede that NaOH and KOH are more alkaline than PBW and the like, however NaOH it is not even in the top 5 chemicals that commonly cause injury in the workplace. Which ones are?

          1 - Carbon Monoxide
          2 - Ammonia
          3 - Chlorine (hence my personal displeasure for chlorine dioxide based products)
          4 - Hydrochloric Acid
          5 - Sulphuric Acid

          Okay, maybe that isn't the world, but 9 states is a pretty good sample size. I'd bet you would find it holds true throughout the world with concentrated Hydrogen Peroxide (or other oxidizers) ranking as the top industrial hazard. That's my anecdotal from a previous life as a haz-mat responder. Oddly enough the most common workplace incident requiring medial treatment was a box cutter when I was working a research facility with all of these top 5 in use every day. Could hardly get past 30 days.

          PPE should not be overlooked for metasilicate based products either, and I think you would find equal recommendations from manufacturers in handling procedures for both metasilicate and caustics. Granted, I am not freaking out when I dip past a glove in PBW, but either way I'm stripping it off and washing my hand within a minute or two. All chemicals can be dangerous in concentrated form and should be treated with respect.

          I would argue that NaOH or KOH are not practicably more dangerous than metasilicates. Both metasilicate and hydroxide are considered a "3" in health on the Hazardous Materials Identification System (HIMS). Hydroxide is more reactive and receives a "1" in reactivity. It is also considerably more toxic in terms of ingestion limits, but hopefully we aren't drinking either of them because both could kill you. All it takes is gloves, glasses and skin protection. It's not like you need a level A chemical resistance suit.

          It is a good point on the temperature stresses and metal fatigue. It is not only welds that are suspect, but poor quality nickel steel itself can form micro fractures. I have not seen this happen on anything North American or European, however I have seen this on poor quality Chinese equipment. It is always best to start with the least aggressive procedure that offers acceptable results for these reasons. The alloy content is very important. If you have true 316 or 304 austenitic and the welds are of high quality, then you will have no problems with any of the suggested methods or chemicals in this thread.


          • #6
            This is all great info to have. Do you happen to have info on the dangers of inhalation of vapors on these chemicals? A concern of mine. Its difficult to mix these cleaners in a brink and not breath in some amount of vapor.


            • #7
              Read your SDS

              This information is in the SDS for each chemical preparation, and is specific to each. Your supplier should provide these for you as a matter of course.


              • #8
                One point that I rarely see brought up in this discussion is the fact that long term the non-caustic is easier on equipment.

                The brewery I work for uses non-caustic and has so for 20 years. We've seen both our soft parts including hoses and our stainless last much longer than industry averages. In fact a brewery in the same area that purchased the same equipment as us has had to replace their fermenters due to weakening of the metal around the glycol jackets. We had the same welder that diagnosed their issue assess our equipment in much better condition than theirs. The difference was they use caustic.

                Our 3 breweries are consistently making clean beer as confirmed by our lab. So, non-caustic certainly does a sufficient job in cleaning. The downside is silicone staining from the non-caustic. We keep some chlorinated caustic around to remove that on occasion and for really tough cleaning tasks. I would really recommend non-caustic as a regular cleaner.


                • #9
                  Do you have a product suggestion Jeff??

                  Jeremy Reed
                  Co-Founder and President, assistant brewer, amateur electrician, plumber, welder, refrigeration tech, and intermediately swell fella
                  The North of 48 Brewing Company
                  Regina, Saskatchewan, Canada



                  • #10
                    I do not believe there is a real risk of degradation of real 304 or 316 austenitic steel with use of NaOH in a brewery setting. I have used much higher concentrations in bio-reactors for extremely prolonged periods of time with very minimal effects. This supports the data I have seen.

                    Here is some data from qualified resources on the risks of stress cracking, corrosion, and sodium hydroxide.
                    The Hendrix Group, Inc. provides best services. Our services are "Asset Integrity", "Materials Consultants", "Corrosion Consultants" and many more.

                    There are no significant risks at the temperatures and concentrations we are typically seeing. We would basically need to boil the caustic before starting to worry about severe degradation of the metallurgy. The weld points are often the weakest due to temperature and alloy differentials, but even the rolling of steel can impact its potential for stress cracking. There are a lot of factors that can weigh in, however quality equipment should have no concerns of any procedures or chemicals mentioned on this post.

                    As stated before, its always best to use the least aggressive method with acceptable results from an equipment perspective. You have to factor cost, availability, equipment compatibility, enviro/social impact, and effectiveness in choosing the right procedures. The chelators, surfactants, and detergents present in each chemical vary (as Dick says) so you may have more or less effect based on brands and water composition too.

                    Metasilicate is easier on the EPDM rubbers than NaOH, but both have good resistance. Silicone is rated excellent against NaOH. Hypochlorites are a bit more aggressive. Pick equipment based on cleaners or cleaners based on equipment, but ensure they are compatible. PPE should really be the same for all those mentioned, except dry chemicals can have respiratory concerns as well.


                    • #11
                      Just to add to the comment about hypochlorite usage - which has all been said in a number of other threads over the years.

                      Typical concentration 150 to 200 ppm, absolute max 250 ppm chlorine. pH of solution, 11.0 + for maximising protective effect against chlorine induced corrosion. Max temperature typically quoted (by my chemical supplier contacts) as 65 deg C - but occasional blitzing at higher temperatures, providing pH > 11, is normally OK. And ideally don't use on plate heat exchangers as with the best designed & constructed ones are still liable to accumulate around the edges of the gaskets, due to slight flexing with temperature and pressure changes - leading to chlorine pitting corrosion which can develop into crack corrosion between the pits. Not that that has stopped me using the stuff on PHEs occasionally - but definitely out of urgent necessity only, not routine.


                      • #12
                        If you’re saving the co2 in your brites you’ll need the pbw. So start there. Get a good acid regimen to prevent scale. Chech your tanks after a month or two and see what you think.

                        I enjoy the security of knowing that helpers cant implode a brite or ferm if im not around to watch them. Not alot of brewing history in mexico, virtually zero folks with professional education, not many more with decent experience. (At least outside the majors like modelo/cuatehmoc/etc.) And those guys aint leaving to come work a little craft brewery.

                        Nothing says you cant use caustic on a quarterly or semi annual basis for deep clean/passivating.
                        Last edited by brain medicine; 02-25-2019, 10:13 AM.


                        • #13
                          Originally posted by Jer View Post
                          Do you have a product suggestion Jeff??

                          We use Brew-Clean from Brew City Solutions.


                          • #14
                            I have used flaked KOH for over 10 years and have yet to have a problem with it.


                            • #15
                              Originally posted by brain medicine View Post
                              If youÂ’re saving the co2 in your brites youÂ’ll need the pbw.

                              I enjoy the security of knowing that helpers cant implode a brite or ferm if im not around to watch them.

                              Nothing says you cant use caustic on a quarterly or semi annual basis for deep clean/passivating.
                              Nothing says you can't use NaOH/KOH every time. You can't use it for passivation though. It won't remove free iron.

                              You don't need PBW to save co2 in the brites. You can use an acid based cleaner under pressure. Also, PBW wont eliminate your risk of vacuum. Temperature alone can be enough to vacuum a tank like foil, with no chemicals at all. I would suggest it is probably more likely to vacuum a tank than the 1-2% caustic solution, but I'd have to get back into molar equations before I care to break that down further, and it would probably depend on tank size.

                              I will second the "third world" helpers comment. Been there. I prefer an "atmospheric" cleaning procedure with an open tank, but will use a closed pressure acid loop on brites to save o2 pick up (not so worried about saving the co2 myself). I make sure to supervise anyone that I feel is less than capable of full responsibility, or do it myself whenever possible in those circumstances. It only takes once, but no-caustic does not equal safe. Hot cycle to cold rinse can vacuum a tank just as quick.

                              I think the biggest advantage to metasilicates is the compatibility with aluminum. Great for lower end canning/bottling lines that have aluminum parts.