Did I miss what your issue is exactly?
I have been having issues lately with a couple of our carbonating stones. Basically we clean them by soaking, scrubbing and blowing co2 through them simultaneously in both a caustic and acid bath. All seems well when cleaning. We are getting many signs of pressure coming through the stones while in the cleaning buckets. Do the stones have a life span? Are the channels in which gas passes bendable? When I've taken apart the valves that we have attach to the stone and inspected, all seems clean and well to the naked eye. I've seen a couple of posts relating to this issue, but I did'nt get the answer I desired. Any help would be great.
Did I miss what your issue is exactly?
Bear with me as i type this from my phone, but we have had many similar problems with our sintered stainless stones. Are you backflushing and soaking in acid? How long have they been in service? Our stones, after several years of service and probably rough abuse, i.e. dropping in buckets of san and dropping clamps and other misc. parts on them., pulling them in and out of ports will close the stainless pores and become "ineffective". We have tried pumping 120 psi through them to no avail. In some cases, its time to replace them unfortunately....
Any one else have these issues?
First of all, don't blow CO2 through your stones as they are being cleaned in caustic. You just render the caustic ineffective. Carbonation stones don't have a life span--or it's measured in decades if there is one. That said, dropping clamps and other fittings on the delicate porous surface of the stone will smear the pores closed and will lead to less available surface area. Some stones have larger pores than others. Keep them clean and damage free. Take the time to treat them right. Like jewelry. Don't use a wire brush to "clean" them. Visit some other threads here for cleaning tips. And make sure you have a good check valve installed immediately at the stone to prevent beer from backing in the carbonation lines and plugging your stone with yeast. Ditto with oxygenation stones. With care, a quality stone will last a long, long time. But toss a Chinese stone in a bucket of parts every day for a year and you'll throw it away.
Palau Brewing Company
Besides cleaning we remove the check valves and backflush with 180 water.
VP of Operations / Zymurgist
Bluegrass Brewing Co
636 East Main St
Where I used to work we never had problems with pores clogging on our carb stones. We used the 11 piece Zahm & Nagel SS stones. After emptying the brite tank we would break apart the stone into its 11 pieces, rinse with water and then soak all parts in non-chlorinated caustic diluted to a 25% concentration. After soaking for at least a couple hours, all the parts were rinsed thoroughly with water. The stone was placed into a pressure cooker, and steam sterilised under pressure for 15 minutes. Essentially, the pressure cooker is being used as an autoclave with 'wet steam' which is one of the most effective ways of sanitizing. After autoclaving all parts were sprayed with a mild PAA solution before being reassembled. After assembling the stone was placed in a diluted solution of PAA and CO2 was blown through the stone to ensure all pores are clear and the stone was put back together properly. Then the stone was put back on the tank before a PAA CIP.
I know this procedure may seem a lot longer than what a lot of other brewers do, but we never had any issues with our stones clogging or contaminating our beers. A carb stone is porous and can be a perfect spot for biofilms once pores start to clog. Make sure you always remove your carb stone as soon as possible. Don't let it sit in an empty and dirty tank. I agree with Phillip that your stones should last a long time. Also, if you have ceramic stones you will need to follow a different procedure than you would follow for SS. My experience is only with SS, so I would contact the manufacturer if you have ceramic stones.
By the way you can get a pressure cooker and burner at Walmart for less than $100.
Hope this helps.
looks like there are electric pressure cookers out there also. Does anyone have experience using these? they would save you the danger of having an open flame in the brewhouse with a propane or butane burner.
We used cornelius kegs for a chemical solution (caustic/rinse/acid) and pushed the chemical through the stainless steel stone. While not in use, s.s stones were soaked in a phosphoric/nitric acid. As mentioned in a previous post, make sure you have check valves installed and don't use a brush to scrub!
Originally Posted by Wild Onion Pete
Thanks to all the replies. Very useful information.
25% caustic seems like an awful lot. Is this figure correct?
We boil ours in a pot on the stove with a %4 acid solution every few months.
Sometimes amazes me what comes out.
We use the acid cleaner we use for regular acid wash of tanks.
Wear goggles if you're going to try this. Also make sure the sink is full of cold water when you dump the boiling acid solution out of the pot.
Works like a charm, I find. Regular cleaning is caustic in bright tank cleaning loop. Regular storage is in peracetic sanitizing solution.
No! Its not correct, my mistake. Our Caustic in the container was at 20%, and then we would dilute that solution to a 25% solution. So roughly 5% was our concentration.Originally Posted by obvance