I finally found a medical oxygen tank on Craigslist at the right price. It has a regulator, but I heard a podcast some time back stating that one also wants a flow meter on it so that one can be more consistent in dosing the wort.
What do you think?
Most advice you find says 1 liter a minute for a minute per 5 gallons of a standard ale (something about 1.050). You go longer for high gravity or lagers.
I too did a bunch of research before getting my O2 system; I settled for a small tank for welding (easy to get filled/exchanged), and the flow meter is integral to the regulator on my unit. It’s a 1-4 LPM device I got on Amazon for $50 http://www.amazon.com/gp/product/B006980HS2/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1
This one’s configured for a CGA 540 connection to the tank - yours may be different. Only issue I had was the fitting on the output - it a DISS outlet for medical fittings and is specific to Oxygen (thread size and pitch) so I had to order from a medical supply. Got the fitting and an elbow, a master ON/OFF valve and nipple out to the hose - this thing works great!
Or use the wort as a flow meter? If too much O2 is leaving the surface, turn down.
Well as it turns out I just need a little schooling on what I bought.
The little number 1 on the left indicates the flow rate which in this setting is 1 liter of O2 per minute! It can’t get any easier. This tank will last me for years and then is only $15 to exchange. No more messing around with those little red cans and the horrible regulator that I’ve been using on it.
Where do you get it refilled?
The short answer is: at a local medical supply store. They just exchange it on the spot for a full one.
The longer answer is that this tank was purchased from Lincare, a national company. They WILL NOT exchange or refill one of their tanks unless one has a Dr’s. prescription. I thought I was out $100. Until I went to the local mom-n-pop medical supply store. They said they could do it. But then showed me that the tank was full - I just had the main valve off. I’m happy again.
Easy way… find tare weight on bottle. Weight it. The difference is how much gas you have.
I don’t even know why we are worried about medical vs welding 02. I have used welding exchange five lb tanks for years with no problem. Throw a cheap Harris gauge on it and you are there. You will get at least 40, 5 gal kegs out of the tank. I leave it slightly open all the time so it never sucks wort into the sintered stone or metal until I drop it into the starsan.
From what I’ve discovered; oxygen is filled into welding tanks and medical tanks using the same master system, same oxygen, same everything. The difference is when it leaves the filling plant - chain of custody (and tank configuration) is what really separates “medical-grade” and “welding-grade” oxygen.
No matter the source of the tank or oxygen, I’ll still feel better with medical-grade regulators and flow meters - just “feels” more sanitary to me.
For me it was which unit I found first at the price point I felt was reasonable. I would have totally sprung for a welding tank - this one just came up first. I have to say that I love the regulator far more than the welding variety though.
You can get a CGA540 version of the medical regulator, which fits welding tanks. See the amazon link above. I use one and it makes it very easy to control the output since it’s designed for low flow.
Flow meter is best, but in a pinch you can also use a small ball valve and a sight glass (or the bubbles going through the wort) to gauge the flow. You don’t really need a flowmeter.
A quick report on the first use. It couldn’t have been easier. Set the regulator to 1 liter/minute, stick the aerator wand in the wort, turn the main valve on and start the timer for a minute. Pull out the wand at 1 minute and shut the main valve. So glad I found this!