EnidPuceflange wrote:Just so I'm clear what you're doing (I too brew, so I'm curious ) - you're using this to step mash, right? For non-brewers, this is the process where the grain is heated to a very specific temperature in water (it looks a lot like oatmeal) and the steam (if I understand correctly) is being used to raise the temperature of the mix by specific steps.
If that's the case, then you don't care about sterility - it'll be boiled afterwards anyway - but you want a lot of steam on demand, and the ability to shut it off and turn it on (which might cause some issues here).
Of course I could be totally wrong on this, like so much else
That's correct, i want to be able to step mash. I don't care about sterility, but i also don't want rust in the mash. Whether or not the rust would make it into the mash i don't want to debate, i just don't want to take the chance. I think steam would be the best way to do this without scorching the mash or wort. I'd use a solenoid to turn the steam to the mash on and off using a controller, and the controller would also monitor the vessel pressure and turn off the element at the setpoint.
hammermill wrote:some thoughts. many comerical steam kettles as used in restaurants are in essence what you are talking about. one stainless element like you mention can also be found in dishwashers and in the surplus world at one time I thing surplus sales has them.
as you may know many a piece of brewing equipment has been ruined by someone leaving water with a chlorine concentration in it stand . a whole new brew pub suffered this fate a few years back.
I don't think i would have any chlorine content in the water. I'm on a well. We have very clean water here.
I'm sorry, but 10 psi. isn't going to give you what you want. Water boils at 212 degrees F at sea level. If you want to raise the temperature to 240 degrees F, you will need a pressure of 240-212 or 28 psi., since for the first 100 psi. of steam pressure, the steam temperature rises by 100 degrees Fahrenheit. I'm not sure what happens after that, but for the first 100 psi., the pressure/temperature curve is linear (or close to it) at 1 psi. per degree Fahrenheit.
The 10 - 15 psi range is about what you would see in a pressure cooker (1 atmosphere), but 30 psi. would give you quite a bit more stored energy and when misused, even pressure cookers can fail quite spectacularly. I'm not saying, "don't do it;" I guess what I am saying is that it does require a lot of thought to come up with a safe, workable solution. Probably some form of periodic hydrostatic testing at multiple times working pressure should be incorporated in the plan to be on the safe side.
You should also have at least two safety valves (required on our steam locomotives) in case one fails and also some form of pressure switch or sensor that would cut off the power to the heater if it goes over the normal operating temperature.
Just my ideas, I'm sure others will have more.
Richard Trounce.
Richard, are you sure? I think the steam table i was looking at showed equilibrium temp for 10 psi at about 240. That seems to be what everyone i have seen doing this has also seen. I think 2 safety valves might be a good idea. As i stated, we would be controlling the element using a pressure sensor. At setpoint or above, element is off.
You're right. 10 psi. will give you close to what you want. As you know, steam would make a great temperature control medium, just like a double boiler on a kitchen stove.
I checked and the pressure - temperature relationship is decidedly non-linear. Delta T is greatest at the low end of the relationship and gets smaller as you get closer to 100 psi.
At 5 psi., Delta T (temperature differential per 5 psi. change) is 16 degrees F. At 10 psi., it drops to 12 degrees. By the time you reach 50 psi., it is down to 5 degrees per 5 psi. change and at 100 psi., it is 3 degrees per 5 psi. change. Non linear for sure!
Not only that, but at 100 psi., the temperature isn't 312, it is 338 degrees F.
I learned something today! Thanks, I had assumed that what I was told was right.
) - you're using this to step mash, right? For non-brewers, this is the process where the grain is heated to a very specific temperature in water (it looks a lot like oatmeal) and the steam (if I understand correctly) is being used to raise the temperature of the mix by specific steps.