Steam Injected Mash System

In case someone is interested, I've done the preliminary analysis and investigation and I'm going to be building a steam boiler from a corny keg to supply steam for heating my mash.

Its not nearly as scary as it sounds.

Description

The corny keg will get a 4.5KW hot water heater element installed in the bottom. A temperature sensor will be installed in the top. A small $35 computer will monitor the temp (and other things about the brewing process) and turn the heater element on and off with a set point of 240F. A laptop computer will be used to control and monitor the process computer.

The pressure in the keg will be about 10 PSI. Corny kegs are rated for 130 PSI. A 15 PSI pressure relief valve will be installed to prevent any over pressure situations from occurring. Keep in mind that this is less pressure than a typical automotive cooling system. The keg will be pressure tested to 30 PSI with tap water before being fired up.

The keg will be equipped with a simple valve manual or computer controlled on-off valve for delivering the steam to the mash.

Parts List

The parts list is this thus far (McMasterCarr part numbers where applicable.)

1 good corny keg
1 4.5 KW hot water heater element, screw in (3555K32) $6.80
1 self sealing nut (5530K23) $4.90
1 pressure relief valve (4893K25) $7.70
1 bulk head fitting, nickel finish 5483K93 $9.80 for 2
5 feet high temp NFS hose 3184K1 $1.47 per foot
1 high temp electric solenoid valve 4807t21 $51.02

There are a few misc fittings missing from this list as well as the computer and relays or SCRs for turning the heater and control valve on and off. Temperature measurement will be done with a $3 thermistor.

Usage

The computer will be programmed from a PC to bring the strike water in the HLT and boiler up to their start temps (135F and 240F) respectively. It will take about 20 minutes to bring a nearly full keg up to 240F. The HLT will be electric heat as well, so that will take another 15 minutes or so.

Dough in will occur. There will be a temp sensor in the mash vessel, actually multiple of them on a floating thermometer setup.

When the computer senses a temperature differential in the bed, it will turn on the recirc pump to even things out.

When the computer senses the bed is too cool, it will modulate the steam valve a few times, injecting some steam, to heat it up.

As soon as the temp in the boiler drops, the heating element will be turned on to bring it back up.

At the first mash temp step the computer will change the temp setpoint from 130 to 155F and open the steam valve accordingly. The recirc pump will kick in. The operator will be encouraged to stir the bed.

The thermodynamics are such that the steam created from a corny nearly full of 240F water is enough to heat the mash from strike temp to mash out. The steam can be added as fast or slow as desired by throttling the flow. It will be possible to raise the temp of a bed containing 10 pounds of grain by over 20F per minute. Gone are the days of waiting around for the bed to get to the next temp. Multiple temp mash schedules should be a breeze.

The amount of water in the injected steam to heat the mash from strike to mash out will be small, less than a quart.

The boiler will contain 15 Litres of 210F water at the end of the mash out. It can be used for cleaning or sterilizing the counter flow chiller. It could also be used to top up the boiler if the sparge volume is less than the boil volume.

This is going to be one hell of a system.

I'm gathering bits and cropping ideas. There's no way I'm going all the way with it but I reckon I can use some of the ideas.

Are the controller and software going to specific and hard wired for the system you build or d you think it'll be adaptable to lesser/other systems?

Are you still going with the SIMS tag?

Are the controller and software going to specific and hard wired for the system you build or d you think it'll be adaptable to lesser/other systems?

Click to expand...

The controller will be the arduino board I've spoke of before. I'll make my code for it and the Java GUI that runs on the laptop open source. People can do what they want with it.

Are you still going with the SIMS tag?

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Until someone gives me a better acronym ! I'd like to call it SIMPLE or something like that.

MISH: Mash Injected Steam Heating.

You could MISH your mashing ! or MISH mashing. Try saying that 5 times after drinking 4 homebrews.

I have yet to brew an all grain, so I may show my ignorance. I understand that when the mash reaches 170F, something happens to the enzymes. Will injecting 240F steam be bad for the areas right by the steam injectors?

Is the Ardino board capable of self tuning? I am assuming it is a PID?

I have yet to brew an all grain, so I may show my ignorance. I understand that when the mash reaches 170F, something happens to the enzymes.

Click to expand...

According to Dave Miller, they stop functioning. That is why the mash out temp is set there.

Will injecting 240F steam be bad for the areas right by the steam injectors?

Click to expand...

Truthfully, I don't know what short term exposure to 240F would do to the mash. I know that people run RIM systems or use a heatstick and the temps are way higher than that in the vicinity of the element. Ditto for the bottom of the pot when its on the stove. So I think that 240F will be OK.

Is the Ardino board capable of self tuning? I am assuming it is a PID?

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*chuckle No, the Ardiuno won't be self tuning. It needs to be programmed a bit. Its not a conventional PID controller, although we could put a PID algorithm in it. Truthfully, I am not sure that a PID controller would work for the steam process. I guess I'll see what the temp response is to steam injection.

http://www.arduino.cc/

For those that are afraid of "programming", this might be interesting
http://www.arduino.cc/en/uploads/Booklet/Arduino_booklet02.pdf

Will the corny seals hold up to the heat?

Remember the Challenger!

Ahh, k so basically an i/o board that is easily integrated with a pc. Most controllers I have seen are PID. Sounds like you've got lots of work ahead hehe (fun project btw). The step response is probably a good place to begin, and hopefully you won't have to get terribly complicated, although to hit your mashes without overshoot will be interesting because your amount of grain will usually be different. Geez I miss control systems stuff.

olllllo said:

Will the corny seals hold up to the heat?

Remember the Challenger!

Click to expand...

Buna N seals are good to 250F operating temp.

http://www.marcorubber.com/materialguide.htm

Ahh, k so basically an i/o board that is easily integrated with a pc. Most controllers I have seen are PID. Sounds like you've got lots of work ahead hehe (fun project btw).

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Shouldn't take long at all.

I just ordered the McMasterCarr parts, btw.

The step response is probably a good place to begin, and hopefully you won't have to get terribly complicated, although to hit your mashes without overshoot will be interesting because your amount of grain will usually be different.

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I don't think there is much system inertia. I don't think overshoot will be an issue. It will be interesting to see. Hopefully I can just open the valve and watch the temp. When the temp gets to the setpoint, shut the valve.

Unlike other systems, the thermal capacitance of the heating components in the mash is just about zero. I guess we will see.

Here is an email I sent a guy on this topic.




So here is my attempt at mash boiler thermodynamics. Be kind... I am really rusty with my steam calcs.

My data source is http://www.chesterton.com/interactive/tables/steam/

Water and steam at 1atm, 212F. The liquid has an enthalpy of 180 btu/lb and the steam portion has energy of 1150 btu/lb

Water and steam at 25 PSIA (10 PSI), the temp will be 240F. The liquid has an enthalpy of 208 btu/lb and the steam portion is 1160 btu/lb

Straight liquid at 126F at 2PSI has an enthalpy of 94 btu per pound. Straight liquid at 170F at 6 psia has 138 btu per pound. For now we will ignore the energy due to pressure because water is nearly incompressible and that energy change is near nothing.

So to heat water (our mash) from 126 to 170F takes 138-94 = 44 btu per pound. Which makes sense because the temp spread is 44F and water has a specific heat of 1btu/lb.

Lets say we are brewing a beer that uses 10 pounds of grains. Using this page http://www.rackers.org/calcs.shtml and a water ratio of 1.25 q/lb, it will take 3.93 gallons of volume. Lets say that is all water at 8.33 pounds per gallon, we'd have 32.7 pounds of "water". In reality, it will be both lighter than that and have a lower heat capacity. But using these numbers, the total energy to raise our mash from 126 to 170 would be 32.7 x 44 btu = 1440 btu.

If we were direct heating, a 4.5KW element puts out 15,354 btu/hour or 256 btu/minute. Our water weighs 32.7 pounds so we would get 256/32.7 = 7.8F per minute. That is a pretty good heating rate as far as these systems go. Most are 3F or less per minute.

Now cooling steam from 240F to water at 170F will release 1160-138 = 1022 btu/lb. We need 1440 btu, so that is 1440/1022 = 1.4 pounds of steam = 0.17 gallons = 0.676 quarts. A little over 2 cups of water. Pretty incredible, isn't it !

Now how much energy is stored in the corny ? Assume we have 10L of water (22 pounds) and 9L of steam.

First the water part. When the valve is opened, the pressure will drop to 1 atm and any water over 212F will boil away as steam. And all that will be left is hot water at 212F. Neglecting the change in mass, we go from hot water at 240F to 212F, so that is 28btu/lb x 22 pounds = 616 btu.

Now the steam part. We have 9 L of steam at 16.31 ft^ per pound. 16.31 ft^3 x 1728 in^3/ft^3 /61 in^3/litre = 462 litres per lb. 9L/462L/lb = 1.94 x 10e-2 pounds. That steam has an energy of 1160 btu/lb so 1162 btu/lb x 1.94 x10e-2 lbs = 22.6 btu. Not nearly as much as the hot water because there is little mass.

The boiler energy storage will best work on the principle of heating the water up to a temperature higher than boiling at atmospheric pressure. Like 240F at 25psia. Then when the valve is opened, the pressure drops in the boiler and the water boils, making steam. Just like if you open the radiator cap on a hot car engine.

That is much different than a pressure cooker principle, where one is just capturing what the stove is boiling off as it boils.

Now... if one had the whole corny full of 240F water, then we'd have 19L x 2.2 lbs/litre x 28 btu/lb = 1170 btu stored up ready to go. Almost enough to do our whole batch. We need 1440 btu to go from 128 to 170F.

One could probably release the 1170 btu in about 2 minutes. That would give us a heating power of 1170 btu x 60 minutes/2minutes = 35,100 btu per hour from the hot water alone. 1 KW = 3412 btu/hr so 35100/3412 = 10.2KW. Plus the 4.5 kw element will cut in and add to that, so we have about 14.8 KW of of steam power going to the mash ! That is 50,453 btu/hr or 840 btu per minute. Our mash weighs 32.7 pounds, so the temp rise would be 25.7F per minute !

So a mash temp rise from 128 to 154F would be 32.7lbs x 26 btu = 850 btu, which is almost exacly 1 minute. One would have to throttle the steam flow so that you didn't overshoot on the temp. But on the other hand, you know how many btus is going into the mash from the boiler temp change if you wanted to get fancy ! The computer could measure the temp before and then watch it until it drops the right amount.

Now... how much energy are we putting into heating the water ?

19L x 2.2 = 41.8 pounds. The temp rise will be 240-60F = 180 btu/lb. So 41.8 x 180 = 7524 btu. 1 KWhr is 3412 btu/hr so 2.2 KW Hr of power or about 20 cents worth to get the water ready in the boiler. WIth a 4.5KW element, that should take 7524 btu/256 btu per minute = 29 minutes. If one started the element when the mash started, it would be ready before the first step. Cool ! At the end of the run, one will have 42 pounds of water at 212F for washing ! The energy in that water is 212F - 70F x 42 = 6000 btus. One could do a good job of sterilizing a counter flow chiller by pumping that water through it. I also capture the water that goes through the counterflow chiller in the HLT for washing purposes, so neither of that energy is totally wasted.

So... did I get my math and thermodynamics right ?

What do you think of the boiler operation ?

I like how fast it would raise the temp of the mash ! No more sitting around waiting for the temps to rise. If they are going to rise that quickly, I think I want to manually control the valve and stir at the same time. I think I am going to make a floating thermometer for my mash vessel, with multiple thermistors to get the bed temp at various depths automatically.

fifelee said:

I have yet to brew an all grain, so I may show my ignorance. I understand that when the mash reaches 170F, something happens to the enzymes. Will injecting 240F steam be bad for the areas right by the steam injectors?

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Stirring the mash should alleviate any issues of directing hi temp steam into the mash. A motor operated stirring machine would be best (for consistent churn) but stirring by hand while introducing the steam works too. I've communicated with a handful of people that say the steam has no notable effect on their mash efficiency.

HERMS systems put the runnings through quite a bit of temperature differential as it passes through the tubing and heat exchanger and back into the mash. It seems that gently introducing steam would be less detrimental. Of course, I'm relying on others' experience until I get my system built...

fifelee said:

Will injecting 240F steam be bad for the areas right by the steam injectors?

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In theory yes, any enzymes that are heated above 170f will be denatured. They do not simply pause above 170f and then restart once the temp comes down.

As I understand mashing, it should not effect the overall mash if a small area is superheated with steam.

Don't decoction mashes involve boiling some of the wort to raise the temps?

If so, this volume of wort has no enzyme activity, but it doesn't impact the overall conversion much.

How many steam injectors are you talking about here? Is this going to be a steam jacketed kettle, or direct injection?

Since you're already automating most of this system, why not build a grain stirrer as well?

Matt

I think this will be much gentler on the mash than heating over a stove burner or infusion of boiling water or even decotation. And for sure, RIMS, where a hot element directly contacts the wort. HERMs might be be gentler.

The steam will probably come out of a C shaped manifold at the bottom of the mash vessel.

brewman ! said:

Shouldn't take long at all.

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Not for simple do this, do that software no. You can easily set up the computer to throttle the valve etc, vary the duty cycle or some other method to get your setpoint. But to have a closed loop feedback control system specifically designed to do what you are doing could take a bit of time. I guess I'm overcomplicating it, but it seems to me that you really want to be accurate within a degree and that seems like it would be a bit of work to get your system tuned properly. It's all a process though, as I am sure you're aware. Not sure if I am understanding what the vessel that actually contains the mash is. The less lossy it is probably the better for you (I would not rule out heat flow from the vessel, this could really put you in a spin), as long as you can very accurately control that throttle valve. Sorry I don't mean to come across wierd or anything, you've just got the gears turning lol.

The parts arrived for converting the corny into a boiler. Bulk head fittings, element, valve, relief valve, etc. The microcontroller isn't here yet though. It will be a few days until I can find time to work on this. But I will.

Get the camera man.

I think you should start a blog as well.

"Get the camera man."

Got one... actually two.

"I think you should start a blog as well"

Nah. I'll just post here. Blogs aren't interactive enough. I like it when you guys comment. Lots of good ideas here.

You should look into makeing a steam kettle now. Seeing you have a boiler.

Hmmm... very interesting. A pressure cooker would work as well.

Expensive ? $50 !
http://www.amazon.co.uk/dp/B0001P16YS/?tag=skimlinks_replacement-20

This one is a plastic tank with a heating element. 2KW isn't a lot of power, but then again, a lot of the RIM systems are running with 1-1.5KW to avoid scorching the wort. This thing would be very easy to build.

Not to brag, but my element is 4.5KW.

Then there is the matter of storing superheated water. The wallpapers steamers will work, no doubt about it. But they aren't a pressure vessel. They make steam at atmospheric pressure and that is fine. It will work for heating the mash.

When done, my boiler will store hot water at 240F at a pressure of about 10PSI. When the steam line valve is cracked the pressure in the boiler will drop to atmosphere and all that hot water will boil, making steam. So my boiler actually stores heat energy ready to use. That is how I can get mash temp rises of 20F per minute if I want them.

Here is a more robust wallpaper steamer. It appears to have a metal tank and it probably runs at a higher pressure.
http://www.taylorrental.com/item_detail.asp?id=33

I didn't get to work on my steam stuff today and probably won't for a week.

I don't understand any of this, but I will certainly bookmark it and check out the links when I have some quiet time... Sounds awesome!

Don't know if he's already chimed in on this thread, but Sudster uses steam injection to heat his mash. I picked his brain (eww) a while back and he's very pleased with the success of his system. Pretty simple concept...

Here's a pic of his pressure cooker steam "generator". https://cdn.homebrewtalk.com/gallery/showimage.php?i=6

I like the automation with computers and it seems like you could build on this as time goes on. After a few years you might be able to flip a switch when you go to bed at night and wake up with a bubbling carboy of fermenting beer.

Here is an alternate approach to steam use and generation, propane fired flash boiler that is used to inject steam into the recirculated wort for heating. Same boiler is used for heating strike water at higher flow rate, generate steam for temperature increase, and heat sparge water to 175 deg. Materials used were a 30K 6" burner, 6" stove pipe, and 4-10' long pieces of 1/4" stainless steel tubing wound around a 2" pipe. this setup requires some method of feeding water to boiler, and a recirc pump for the wort.

I don't understand the pros and cons of wet, dry, saturated, and superheated steam, and why one would want one versus the other. Do you know?"

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Yes. Lets leave those terms out of it and talk about superheated water.

Superheated water is water heated above its normal boiling point (212F) but kept as water by applying pressure to keep it from converting to steam. If we keep the water under about 10 PSI of pressure, we can heat it to 240F without it boiling.

So at 240F and 10 PSI, I will have a boiler full of water. There won't be any steam. The reason I want this is because water is very dense compared to steam and thus I can have my boiler hold a lot of energy.

Now, when I open the valve on my boiler, the pressure drops. And when the pressure drops, that superheated water starts to boil. In effect, the liquid water under pressure releases energy as steam. It will go from 240F down to 212F as the pressure goes from 10PSI down to 0 PSI. It will reach equilibrium at 212F and 0 PSI. The energy lost between going from 240F to 212F is the amount of steam energy it will release.

The difference between storing superheated water and generating steam by boiling water is that superheated water stores energy that can be used to heat the mash quickly. When I open the valve on my boiler, all the energy in the water from 240F down to 212F will be released as steam, plus the energy of the element if it is on.

When one boils water in a pot without any backpressure, there is no superheated water and there is no pressure change. Very little energy is stored. The energy you get is that of the heating element and that's it.

Superheated steam is steam heated above its boiling point. Steam will absorb more energy than it does at its boiling point. So we could superheat steam at 0 PSI to 240F. (Normal boiling point is 212F, so we get 28F of superheating. The problem with superheating the steam is that steam is very light compared to water and it would take a very large vessel to store enough steam to absorb the same amount of energy as superheated water. In fact, steam takes 1600x the volume that water does for the same weight. (Steam stores more energy per pound though... but it still takes tons more volume to store energy as steam than as superheated water.)

I like your corny steam vessel idea, but I just wonder if it will be safe enough... and there are a lot of commercially produced items that might be as effective and possibly safer since they were designed to make steam rather than to serve beverages.

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A corny keg is a pressure vessel. 240F is way below the temp at which stainless steel or brass or copper or even plain steel starts to weaken. The nice thing about using an electric heating element is that there are no electric or flame burners heating parts of the keg up to 5 or 600F or 1000F or higher, because those sorts of temps can change materials over time and make them subject to failure.

Standard testing procedure for steam pressure vessels is to pressurize them with water to 2 or 3x their working pressure and watch for leaks. Once everything holds that kind of pressure, the vessel is considered sound and rated for the working pressure. Model railroaders test their steam boilers this way.

The relief valve and shutting the element off when the water reaches a maximum safe temp (240F) will ensure the vessel never gets over pressured. The maximum pressure vaporized water can make at 240F is 10 PSI.

Liquid water is another matter ! If the corny was filled entirely to the brim with no air space and then heated to 240F, it could generate enormous pressures because water is incompressible. Luckily we have a pressure relief valve to limit the pressure is these sorts of circumstances. However, with a void space above the water, the liquid water can expand and the vaporized water (steam) will only generate 10PSI of pressure.

There are 2 sorts of things that could go wrong with my steam vessel.

1) leakage or failure at rated pressure, 10PSI. Corny kegs are rated to 130PSI. I'll be pressure testing mine to 30PSI. People carbonate beer at 15 PSI all the time. When was the last time you heard of a corny failing doing this ?

2) failure because of over pressure. My kegs setup will have 3 things to prevent this. 1. A pressure relief valve. 2. A temperature sensor 3. A mechanical pressure gage. Multiple things have to fail and the temperature would really have to rise before my corny would get to an over pressure situation.

I think my steam boiler will be a lot safer than working under an HLT suspended 6 feet in the air.

For example, check out the JR/AR 1.5 to 8KW steamers on the Reimers Inc site. Like I wonder if the little 1.5KW version of this one would do the trick. Of course, unless found used and for a steal, it is likely to be a lot more expensive than your solution.

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There is nothing wrong with using a premade steam generator. A pressure cooker heated by a 1.5KW stove element will provide 1.5KW of energy to the mash, less the heat lost from the burner and tubing and steam leakage loses.

My corny will have a 4.5KW element in it. So even if I didn't store any superheated water, I'll be heating my mash with 4.5KW of power, less any losses. That is nothing to sneeze at !

Storing the superheated water is icing on the cake. I'll dough in and do a protein rest while the heating element in my boiler is getting the water up to temp. Then, when its time to do a mash step, I open the valve and release heat at the rate of 10 to 15KW into the mash. I'll be able to raise the temp of my mash very quickly, all without exposing it to temps any higher than 240F ! That is a very gentle heat compared to a RIM system.

I dislike 3 things about using a flame to make steam. 1) It is possible to generate very hot super heated steam. In my system the steam will be at 240F maximum. As soon as it touches the cooler mash bed, its temp will be lower. Its a gentle heat, good for the wort and mash bed. 2) flames and electric burners generate high temperatures which weaken the boiler and tubing materials over time. The 240F water in my system doesn't get hot enough weaken anything. A flame easily does and without proper materials engineering, vessel or tubing failure can occur. 3) the flame chemistry comes into play. Using a flame with excess oxygen to heat metal things can really affect the metal things over time.

Flash boiler was built about 4 years ago as an alternative to lifting 5+ gallons of 180 deg water to top of gravity stand. Since initial construction have installed flowmeter and thermometers to monitor process temperatures. The output from the boiler is tee'd into the wort flow to the mash tun with no valving in the discharge line. Temperatures are regulated by needle valve in gas to burner and needle valve in water to bottom of coils. Have experimented with steam temperatures to 300 deg but found that it was the quantity of steam delivered that counted not the temperature. The secret to steam mixing quietly is copied from commercial steam/water mixers, perforated steam diffuser and moderate flow rate past diffuser. The current system is able to raise 1 gpm of wort from 125 to 148 degrees with no signs of scorching, as the steam temp was 219 deg at start and dropped to 212 at end of 11 minute step as gas was throttled to control wort temp.

Does your 4.5KW heater require 220 volt service or can it run on 110?

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The 4.5KW elements I've found are 240VAC.

The max current for a 120VAC circuit is 15A as far as I know, unless one goes to an RV plug. One could get 3600 watts by running 2 1800 watt 120VAC elements, each on its own breaker, of course. One would have to run 2 solid state relays to control each circuit to do that, if one wanted computerized control.

How will the heating element be mounted in the corny keg?

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Drill a hole in the bottom and bolt it in. Thus the 30 PSI pressure test. There are heating elements that could be put into the keg through small compression fittings, but they are more expensive.

Isn't this another possible point of pressure failure? Or is it on the outside?

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It is a point of pressure failure, yes. One could use one of several external wrap around heating elements from McMasterCarr as well. Hmmm... you have me thinking now.

(You may have covered this, already, just tell me if so and I'll go back and read the thread from the beginning.)

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There is no such thing as a dumb question ! I've gotten a lot of ideas from the comments and such that people have made along the way.

Edit: I just checked McMasterCarr. Item #35765K187 is a 2160 Watt 12 x 18" heat blanket. $80.56 ea. You'd need 2 of them to equal the power of my hot water heater element. 2 would just fit. Item 3671K162 is a 1500 Watt band heater. $46.88 ea. You'd need 3 of them. Pretty hard to beat 35555k32 water heater element. 4500 Watts, $6.50 ea. Uses 1" NPSM threads.

I'll let you know how the drilling and pressure testing goes. I'll do the element hole first.

I finally got to work on my mash steamer boiler. You can see the pictures at http://picasaweb.google.com/beermeister1/MashSteamBoiler

I guess this is kind of a DIY project and should probably go in the DIY area. Can a moderator move it there ? Sorry for posting in the wrong forum.

Great pics brewman. Looks like you have a great shop. I can't wait to get back home to all my tools. Please keep us updated. I am very interested in how it works out.

Thanks fifelee.

I was really worried about mounting the element and the bulkhead fittings. I am happy with how well that went. The big hurdle will be the pressure test to see if they leak. I should get that done in the next couple days.

Once the keg holds pressure, its a done deal, it will work.

This thing should rock. Step mashes should be a piece of cake.

Update. I installed the valves and pressure tested it. It held 30 PSI with no leaks. I've got the pressure relief valve set at 15 PSI. I'll run it at 240F, which makes 10PSI of steam pressure.

Its ready to make steam. I'll do that another night.

Pictures are here: http://picasaweb.google.com/beermeister1/MashSteamBoiler

Brewman,

Glad this boiler is working out for you. I want to offer a word of caution though. I work for a supplier of high performance rubber and plastic raw materials, and took a look at our elastomer chemical resistance guide. Your O-rings, if they are indeed Buna-N (nitrile) rubber may not last long under conditions of 240 F and steam/water. You are correct that nitrile is good to 250 F, but under dry conditions only. Nitrile is not recommended for hot water and steam. It will swell up and ooze out of the fitting, or leak.

The kind of rubber that is recommended for these exposure conditions is called EPDM or sometimes EP. You probably can get these from the supplier you cited on page 1, Marco. You would need the O-ring size, which you can get by taking one and carefully measuring the overall ID and OD of the ring (radial dimension), and the diameter of the cross section of the rubber (axial dimension). I just had a look at Marco's site, and, you can get a lot of informantion from the O-ring section of the website, including a chemical resistance guide that says the same thing about nitrile that I found in the guide we have in my lab.

You might also want to be sure you get food grade O-rings as well, since 240 F water will extract who knows what out of whatever ring you use.

This product is designed to work at 175PSI and 250F. It uses Buna N Orings.
http://muellersteam.com/PDF/e14-15.pdf

Here is another device, this one 160 PSI and 250F. Its ASME approved. It uses Buna N Orings and a Buna N diaphram.
"Applications Hot water boiler, heat exchangers and generators"
http://www.airbooster.com/upload/4452_KUKMC- 537.pdf

Buna N Orings are available FDA approved.

The fibre washers I selected were designed for hot water use.

Thanks for your concern. I'll let you know if I have any problems.

Brewman,

So be it. Maybe there are some special compounds that withstand steam and hot water. You may be okay since you won't be using it 24/7. I'd get some EPDM ones if it were me. Let us know how it works out.

Go for Kalrez Brewman. See what SWMBO says when you spend $200 on an oring.

(I explained this in another thread, so I thought I'd copy it here for completeness.)

My setup is going to have an HLT and a steam generator. I am undecided if the HLT is going to be electrically heated or by an electronically controlled propane burner. So heating the strike water and heating the sparge water will be a no brainer.

The steam boiler will only be used for maintaining the temp of the mash and boosting the temp for steps are sparging.

I guess you could use the steam boiler for the source of the strike water and sparge water *with careful mixing and such* but its just easier to have a separate vessel (ie HLT) with its own control system keeping the water at the right temp.

Ideally, this is how I would like a brewing session should go.

Night before: roll out the brew stand. Put water in the HLT and steam boiler. Put the grain in the mash vessel. Plug everything in.

6AM, warm up. WHILE I AM SLEEPING, the heaters in the steam boiler and the HLT come on and get the contents up to temp. For the boiler, that is 240F, for the HLT, about 145F or so.

8AM, mash in. I pump 1.25 quarts per pound of water from the HLT into the mash vessel and stir it. I'm probably aiming for 135F. Once its thoroughly mixed, I go to my laptop and put the mash vessel temp control on auto with a setpoint of 135F. This allows the computer to open the steam valve when necessary to keep the mash at 135F.

I move the temp setpoint for the HLT to mashout/sparge temp, 172F.

I go have my morning coffee.

8:30AM, starch conversion temp step. The computer moves the mash temp setpoint to 154F. This causes the controller to open the steam valve and inject steam into the mash, until it hits 154F. Ideally I am there stirring the mash a bit.

9:30AM Sparging temp step. The computer moves the mash temp setpoint to 170F. This causes the controller to open the steam valve and inject steam into the mash until it hits 170F. The pump is hooked up to circulate the wort and clarify it for a few minutes.

9:45AM Sparge out. Automatic mash temp control is turned off. The pump is hooked up to pump water from the HLT (now at 172F) to the mash bed such that it keeps about an inch of water over the bed. This is controlled by a level switch in the top of the HLT. I adjust the valve on the bottom of the mash vessel so that the wort drains into the boil kettle at a rate of 1/6 gallon per minute. (Sparging takes 36 minutes for 6 gallons.)

I start the boil kettle burner once a few gallons of wort collects in the kettle. If I want to speed this up, I can dump the leftover steam from the boiler into the kettle.

10:15 Boiling starts. I'm adding hops, cleaning up the mash vessel, getting the fermentor sanitized, etc. (Sparging will continue until 10:22AM)

If I am brewing 2 batches back to back with a friend, here is where I will dump the mash vessel (it will be on a tippy) and mash in the second batch, using a combination of leftover HLT sparge water and cold water. I only have to get it close and the steam boiler will bring it up to temp. Actually, we have our house hot water set at 120F, and that is probably close enough for the steam boiler to bring it up to temp.

11:15 I hook the pump up to the boil kettle outlet and circulate boiling wort through the CFC back into the boil kettle. This sanitizes it.

11:30 The boil is done. I turn the cold water on for the CFC. After a few minutes I stop pumping back into the boil kettle and start pumping into the fermentation vessel.

If we are doing a second batch, the mash temp moves from 135 to 154F here.

I direct the hot water out of the CFC into the mashvessel and the now empty HLT to be used for cleaning. When I am done cooling the wort, I have the HLT, mash vessel and steam boiler all full of hot water for cleaning.

11:45 The fermentor is full and capped. I oxygenate for a bit and pitch the yeast.

I dump some of that hot water from the mash vessel into the boil kettle to rinse and clean it with. I circulate clean water from the HLT through the CFC to clean it.

I start putting things away.

Noon. I roll my brewstand into the corner until next week. I'm done ! (If we are doing a single batch.)

12:30 Second batch is heated for mash out.

12:45 Second batch sparge starts

1:20 Second batch boiling is underway.

2:30 Second batch boiling is done, CFC sterilization starts.

3:00 2nd Fermentor is full. Cleanup starts.

3:30 All done with second batch.

Can you get the 24 clock to display on your screen saver. I think that would be the last thing you needed.

Umm... I found we owned a 22 quart pressure cooker ! I think I'll be making that into my steam boiler. I'm talking about it here.
https://www.homebrewtalk.com/showthread.php?t=21888

so why did you abandon the corney? you just spent all that money on parts, did it tank?