Following up from my previous post, I recently bought a digital probe thermometer and a better hose and tried another test round of steaming. What I wanted to see this time was how well the braided hose would hold up to the heat and at what temperature was the steam coming out of the hose. So, here's the setup again:
The hose goes straight from the pressure cooker to the barrel. With the thermometer probe inside, I stuffed a glove into the bung hole and waited for the temperature to go up. Steam was already going pretty well, and initial reading were around 180°F.
As the pressure in the cooker goes up, the temperature of the steam rises (see table). Water, under no pressure, boils at 212°F, but at 15 PSI it will boil at ~250°F. The hotter the steam is that blows into the barrel, the more bacteria/yeast it will kill. As Vinnie mentioned, you want only the strongest strains to survive.
So, I let the pressure build up and checked the temperature again, and I had hit 201°F!
I consider this a huge success. Without a way to control pressure, to hit and stay at those higher temps, being able to bring the barrel temperature to ~200°F is very good. However this is just a local temperature. Both the hose and the thermometer probe are at the bottom of the barrel.
The next step is to build two parts. First, I need to build a way to control the pressure. Second, I need to build a diffuser. Instead of just sticking the end of a hose into the barrel, a diffuser will allow me to disperse that hot steam evenly. And then controlling the pressure should allow me to raise the temperature of that steam much higher. (see that done here)
4 comments:
I'd definitely say 200 degrees is great considering the tools you had at your disposal. And heck, I don't think much of anything is gonna be surviving a temp that high anyway, so I don't think it's a big deal you couldn't get it higher.
Didn't know a steam cleaner could clean a barrel!
Not sure what the official temp for sterilization is, but that's got to be hot enough to kill any bacteria that would be left in the barrel.
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