Fire box and a direct fire pot still

[iliasm]

Hello all,

I'm in the initial stages of getting a verbal approval from the fire department for a direct fire propane pot still and I have a few questions. They visited the site and after reviewing my plans they had concerns around the direct fire.

My setup includes an all steel fire box with that will be manufactured by a local company, it includes an exhaust pipe with an X11 burner from Ward Burners.

Their main concern was no direct fire, to me this very broad but I understand the concern.

Is there any recommended ways to approach this. In regards to sealing the round edges of the pot to the fire box? Or possibly creating a double layer that the pot will sit?

Any recommendations on approaching this would be greatly appreciated.

[whiskeytango]

Why do you want direct fire? My two cents is this is going to cause you more trouble than its worth, and id go for a written approval instead of a verbal one.

[iliasm]

Mainly due to my still, its a direct fired pot still. Yes the written proposal is coming but I wanted to get a few opinions on how to best position this. I know quite a few distilleries in my area are using similar setup and when I tried playing that card it didn't take me too far due to the fact that that they are in different counties.

[Blackheart]

+1 on Wt's comment. My suggestion/opinion is avoid direct fire. And my second (equally valuable, lol) suggestion is to listen to your local code/safety enforcement peeps. Fight them at your businesses peril.

[Scalawag]

I too am in the final stages of dealing with building officials concerning a direct fired still. The fire marshal has no problem, so he says. The actual building official has not signed off on it yet. We'll see. Many folks on the forum discourage the use of direct fire for obvious reasons. Safety should always be a concern and due diligence is required, but personally, I don't have the deep pockets others seem to enjoy and I plan on making it work. I wish you the best of luck. Where about are you located? If I get any valuable information I will pass it along.

[iliasm]

I do appreciate it any tips or recommendations please send them my way. I'm located in WA state.

[OldSpye]

I continue to fail to see how direct-fired still are some sort of bogeyman. There are large commercial distilleries in Scotland (and probably elsewhere) that use direct-fire.

The bottom line is that there's no additional danger, compared to indirect heat sources, as long as a couple of very basic rules are followed - foremost among them being ventilation. Our fire code guy asked us to put an exhaust hood over the still and that was the end of the conversation.

[Falling Rock]

I see direct fire differently. I think direct fire stills are no more or less likely to start a FIRE than steam or electric, and are less likely to cause an EXPLOSION.

I don't see the need to seal boiler to the fire box. If distillate from a leak in the column ran down the side of the still and caught fire, it would be a safety feature compared to vapors filling the room before they found an ignition source. Distillate wouldn't run down the side of a hot boiler to reach the fire box.

Removing "other" fuel would be on my list. Concrete floor and dam/knee wall around the still to contain a distillate spill. Still should be separated by distance or fire blocked from the walls. Deluge fire suppression inside the knee wall. And a panic shutoff for the gas... Any or all of these features should ease the fire inspectors mind.

[Silk City Distillers]

Most of the safety approaches focus on eliminating ignition sources, because the other two requirements for a fire or explosion: fuel and oxygen, are a given in our environment.

That's the crux of the dissonance. How can you simultaneously focus on eliminating ignition sources when a direct-fired system specifically requires an ignition source to work.

The whole notion of NEC 500, classified areas and explosion proof electrics is based on minimizing the potential for the device to become an ignition source, and if it does become an ignition source, that it will detonate in a way that will limit the overall damage. Any AHJ in question is immediately going to go where precedence has been set, like it or not.

So on one side, you have folks that have spent thousands of dollars (or tens of thousands) on putting in place a Class I Division 1 Group D (Explosion Proof) infrastructure to minimize ignition sources, and on the other side, you've got folks saying direct-fired is perfectly safe.

Nary the twain shall meet.

[clearwaterbrewer]

I am less afraid of an open flame still than I am of people leaving the still alone or using questionable still construction practices that let vapor leaks happen... No one will admit the former, and the latter will force us in the direction of someday having to have our stills certified and inspected similar to steam boilers. Say goodbye to anything but very high priced stills....

An open flame still in a well ventilated area and that has no significant vapor leaks is perfectly safe... then again a simple 20%LEL detector connected to the fuel valve solves the explosion issue...

[Roger]

The distillery that just exploded in KY was direct fire. You can see it in their facebook pics. Regardless you need to constantly move enough air through your facility to eliminate the buildup of vapors, direct fire or not. It is especially problematic in the north when it's 30 below zero outside, but you still have to do it.

[Cougar Red Distillery]

Flir thermal imaging camera or most any brand can expose a leak. We use a flir for our in floor heat transfer system for our column. Just to monitor our chiller input temp. It really works well when we want to see the distillation temps across the entire still. Another note: maybe a positive pressure building should be in order. It is simple to put in place and can guarantee the vapor would be removed. If you used a hood system as the barometric relief? the alcohol vapor would exit the building the correct way without any source of ignition on the way out.

[HedgeBird]

clearwaterbrewer:

"An open flame still in a well ventilated area and that has no significant vapor leaks is perfectly safe.."

Flying Red Pig:

"If distillate from a leak in the column ran down the side of the still and caught fire, it would be a safety feature compared to vapors filling the room before they found an ignition source. Distillate wouldn't run down the side of a hot boiler to reach the fire box."

OldSpye:

"The bottom line is that there's no additional danger, compared to indirect heat sources, as long as a couple of very basic rules are followed - foremost among them being ventilation."

Cougar Red Distillery:

"Flir thermal imaging camera or most any brand can expose a leak."

You guys all act like the only potential issue with direct fire is a small/slow leak, or a vapor buildup issue; and as long as you don't have one of those then they are "just as safe". Thats a bit like saying "my car with no seat belts is just as safe as yours with seat belts as long as I am not involved in an accident"

Another issue that no one wants to say is that most direct fire stills available are just not built as well. There are only two reasons people use/build direct fired stills; they are easier to build and they are cheaper to build. While certainly not always the case; folks providing cheaper/easier equipment are going to be more likely to provide lower quality work and less safety features in general.

[Falling Rock]

I have been there when 95% run across the top of the gas fired still (leak in column), pooled, and went poof! Not an explosion, just a poof.

I was sitting beside it! I heard it, but couldn't see the flame and it took me about 10 seconds to figure it out. I cut gas and diluted the flaming pool with water.

Basically a none event, because-

1. I was there.

2. I had a plan if something happened.

3. I kept my head.

4. The flame under the pot lit the ethanol while the amount was small, rather than vapor filling the room.

I think good ventilation and the open flame contributed to a none event. In an electric direct fired still, the leak could have filled the room with vapor until something else ignited it.

[iliasm]

Thanks all - I do also agree that a gas fired still is as dangerous as an electric. With proper management and safety guards its doable and totally safe. I've actually got a lot further in understating the International Fire Code and requirements around this, but I had a question around ventilation.

What type of ventilation are you using for your gas fired stills, is as simple as a Class 2 vent hood or something more specialized.

[Falling Rock]

An over head vent hood might drag fumes/vapors off the floor. But the best setups I have seen are drawing air off the floor behind a knee wall.

[Silk City Distillers]

Wow, glad I'm not the only one who was impressed by the Stranahan's knee wall setup. It's so brilliant because of how downright simple and inexpensive (except for maybe the Class I Division 1 exhaust fan). You get spill control as a bonus too.

[Falling Rock]

The knee wall also allows for the quickest dilution of a liquid spill.

[mendodistilling]

I think the cooking affect and enriching the flavor from maillard effect may have something to do with it too... Carmerlization is flavor. Steam systems are normally trying to avoid coloring or caramelizing affect.