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In this Discussion
- CothermanDistilling February 2015
- dad February 2015
- Elvis November 2014
- grim February 2015
- Grip January 2015
- Lloyd November 2014
- Manofconstantsorrow December 2014
- Myles December 2014
- Smaug January 2015
- Sunshine December 2014
- TheMechWarrior January 2015
Explosion avoidance!!!
Now I know that in many parts of the world there are very tight controls on Health & Safety in the field of distilling. It worries me a bit that in UK we are pretty much left to our own devices.
My concern, a fairly obvious one, is explosion risk and how to avoid it. It only takes a concentration of about 3% vapour in the air to make it potentially explosive. Of course we wouldn't allow smoking anywhere near the distillery and we avoid use of mobile phones wherever possible. But we do have a box of electrics and a pump, both capable of producing sparks, I guess.
What is the intelligence on this? How do you limit your explosion risk? Am I being worried unnecessarily (I think not)?
Comments
there is something like this for stills out there, I forget where it is...
Looks like something out of IP15, Hazardous Area Classifications.
Positive ventilation plus the use of a Carbon Monoxide detector (sensitive to ethanol also) should help. Fire hoses are sensible. These should be independent of the power supply to the still, so you can cut the boiler power and still have supplies available for any fire water pumps.
Plumb in your boiler (over pressure) vent so that it goes into a bucket containing water.
This is going to be a fun thread!
I am not an expert. I learned everything I know from bottle tops and gum wrappers.
To have a problem you need 2 things: fuel and an ignition source. Most everything you'll hear or read can boil down to eliminating the risk of the fuel source, or the ignition source. The last piece is protection of life and safety, these are all the ancillary components that will play a role when ignition source meets fuel source. As a distillery, we have no shortage of fuel sources.
@Coth posted an interesting drawing, it's important to remember these rules change depending on your location, whether it be locally, whether it be different countries. It's important to know the particulars of your area, because what we might do, or need to do in the states might be different than in the UK. The spirit of these rules are all similar, but the specific details and how those are codified can be very different.
When we talk about monitoring the LFL of flammable vapors, we're talking about limiting the risk of the fuel source. When we are talking about installing explosion proof electrics, we're talking about limiting the risk of ignition sources.
Both of these things can go very far, some items common sense (don't smoke) and some a little bit less common sense (do you have a written policy for managing "hot work" like welding or brazing within the distillery once you are operational?).
I'm not sure where that drawing came from, but the rules are significantly more strict in the US.
I can tell you what I'm doing...
No non-classified electrics less than 3 feet above the floor, for a distance of 25 feet from the edge of any vapor source in class 1 div 1. Imagine this to be a large squat cylinder around the vapor source.
In addition, no non-classified electrics within 5 feet of any edge of a vapor source, extending in all directions in a spherical manner. This includes upwards. For your still this includes the boiler, the column, the vapor piping, the condensers, and parrot. For the big 1000l boiler, we specified an explosion proof agitation (class 1 div 1). You guys with electric elements are probably scratching your head. Uh huh.
I would say best practice would be to either not install any electrics below 3 feet, or simply remove any electrics below 3 feet. This includes wiring, outlets, switches, radios, computers, anything. It's not a problem if it doesn't exist. Remember, eliminate the ignition source. Realistically, just get rid of everything under 3 feet on the ground level, regardless. We move fuel sources around all day long. If you imagine the 25 foot radius moves around every pallet jack and hand truck, it's feasible that most every area is at risk.
Same goes for the still area. Get a string, 5 feet, hold it to the edge of anything. Anything closer than 5 feet that isn't Class 1 Div 1 should be moved away, or replaced with an explosion proof or intrinsically safe equivalent. Discus recommendation is the entire still or still house area is considered class 1 div 1.
I would argue that eliminating it is a better solution than replacing it with anything explosion proof, since even EP can fail.
Lots of chatter lately about explosion proof lighting in the still area. Easy answer, don't put lighting over your still. Move it, far. If you have a big facility and want to make it pretty for tours, use a LED spotlight from the other side of the floor. That last distillery fire, my jaw dropped when I saw they had a standard fluorescent fixture literally hanging right over the still, right in the vapor path should the still plumbing fail, way less than 5 ft.
curious... have you visited an open flame distillery yet?
Reading through @grim's protocols with one eye and looking at my setup with the other and OMG I'm doing everything wrong. My still is dripping with elements 2 feet above the floor. Good ventilation but probably (OK, certainly) not explosion proof. Nothing explosion proof.
@Manofconstantsorrow and I, mostly me, did stupid stuff while we were distilling together. I saw a wisp of vapor coming from the surge breaker and.... well .... I struck a match to it to see if it would go boom. Yes, it did. A loud POP and a roar of laughter later we decided that was not cool and slowed the still down a bit (since then I've added a few strands of scrubby to the product condenser and that problem was solved).
Probably should tighten up on safety here, you think?
Not wanting to be a scaremonger here but we had a visit from a friend of mine a week ago who is a research scientist in the food business. He walked into the distillery and immediately backed out, shut the door behind him, switched off his cell phone and then came back in again!!!
The 3% vapour figure came from him. He phoned me yesterday to say that he had been worrying about this since his visit and felt obligated to point out the dangers to me. One of his comments was to point out that we would be much more careful if it was petrol we were dealing with although the dangers with petrol and 92-95% are pretty much identical. :-O
Now it's me that's not sleeping!!
My perspective is commercial at this point, in a commercial facility you'll be doing things simultaneously that you wouldn't be doing at home. You'll be moving barrels, tanks, inventory, finishing, bottling. You've got pallet jacks, fork lifts, warehouse racking. You've got more and larger electrics. You've got employees that might not be as diligent as you are, and hell, you've got the safety of the neighbors and public to concern yourself with, as well as yourselves and your employees, you've got deadlines and orders, and with that comes early mornings, and late nights, and pressure.
Look there are things you can do, and things you should do, and probably some things that you absolutely shouldn't do, and ever AHJ, and even many insurers, are going to have their input into those things.
This is a thread about what you should and shouldn't do, not what you can do.
Can you do open flame? Sure. I've run open flame rigs and am very comfortable with them. But you know first hand the kind of investment it takes to go commercial, you know if you've got investors, they are probably family and friends, and their money is on the line here too. I'm personally not comfortable with that level of risk in our shop.
Everything we do here isn't to protect when things are operating normally. There is never a problem when things are operating normally, it's when things break and get ugly that problems happen. If there is going to be a problem, it's going to be at the worst possible time, with the worst possible set of circumstances.
The stuff I'm talking about is within the level of reach of the small commercial distiller. I'm not talking about dedicated barrel houses, or still houses, big block still rooms, or a blow-out deflagration venting roof. Even so, I think we should have some level of aspiration when it comes to safety. Maybe I can't afford it today, but it's in the plan, and the next investment we make is going to be to improve safety.
I know it's not sexy, and it always stinks to have to make unsexy investments. We're thinking about putting a roof escape hatch on the mezzanine level for additional egress in the case of an emergency. I'm sure it will cost us $2,000, probably $1,000 if we do most of the work. Will anyone ever use it? No. It sure as hell won't help business. But if something happens, and someone is on the mezzanine, they'll need to run more than 40 feet, including a flight of stairs, to get out the door. We're not comfortable with that.
You want to know what's even less sexy to spend money on? Janitorial supplies. What does a master distiller do? He cleans the distillery.
Take some solace that with safety you at least get a neat gadget or two, and maybe a break on your insurance rates.
So yeah, I'm always going to err on the side of caution.
Flame away, pun intended… :)
Grip - You can manage vapor concentrations with ventilation. Now, this is to manage ventilation for vapors released from normal storage and handling. Do not quote me on this, I will deny ever saying it. NFPA 497 as well as discuss make a recommendation for "adequate ventilation" that keeps flammable vapors under 25% of LFL. The recommendation is at least 1 CFM per square foot of floor space when you can not confidently calculate the actual LFL levels. This recommendation exists in other industry sources as well.
If you are in a temperate climate, this isn't a big issue, if you live in anywhere with temperature extremes, this may present a bit of an HVAC challenge for you, this is 6 full exchanges an hour. If you are paying for air conditioning or heating, it may sting a bit. You may need a cool drink, or a hat, respectively.
A good (US) resource for this is:
NFPA 497 - Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.
and this is a great blog post on it:
HAZLOCs and Ventilation and Classification @ SAFTENG.net
Maintaining adequate ventilation levels will also let you reduce the classification in certain areas.
now I agree, if your stillin' area smells like the nail salon in the mall as you walk by, you might want to worry.... but that nail salon is allowed by the fire marshal.... nearly all explosions are multiple gross neglect.... some may throw out some crap about equipment failure, but then you hear 'what really happened' and you shake your head...... I brought up open flames because it is 10x worse than the 5 SD EGKs with a drain slot in them on my 380L, but those EGKs violate the rules you want to go by... Should Lloyd sell sealed EGK caps for pros?
Get high temperature epoxy potting compound and fill your EGKs. The epoxy will harden into a solid insulating block, encapsulating the entirety of the wiring and connections, it will also permanently seal the EGK - you won't need a drip port.
You could argue that this would be better than explosion proof, since the potting compound would completely insulate any connections. Also, since there is no longer an internal air cavity, the risk of a vapor explosion inside the device is moot.
Epoxy potting compound is cheap enough, and one kit will probably do 3 or 4 EGKs. Something like this:
MG Chemicals 832TC-450ML @ Allied Electronics
The only down side to this is if your element dies, the EGK is trash, you'll probably never get the epoxy block out.
I understand, it just seems silly when every bottle of cognac ever made was done with an open flame still... and we are worried about something that may spark once every 10,000 times you use it and the chance of vapor being to the LEL is 1 in 10,000 if you don't commit gross negligence... it is safer than a turkey fryer, that is for darn sure ;-)
EGK ? LEL ? LFL ?
Element Guard Kit
Lower Explosive Limit 3.3%
Upper Explosive Limit 19.0% in comparison, gasoline is 1.2-7.1%
Many thanks CD.
OK, more thoughts on this subject... can we consider a Stilldragon assembly as safe as a gas appliance such as a stove, oven, water heater, dryer, furnace?
If we cannot, why? is there a way to change it?
Could we do a 7" water column pressure test on the whole system and look for leakdown or with sprayed soapy water? Could we have each electric boiler size set up and pay the $1500 or whatever UL on-site rating fee?
If we can consider it as safe as a household appliance... a 5' radius and 3' floor are not needed...
( I still agree and will be changing/moving my flourescent lighting and keeping arc sources such as relays/contactors as far as feasibly away)
Sure, you probably could, but it wouldn't mean that it's not still a classified use. My explosion proof motors are UL listed.
I am not saying xp motors are not better, they are.. (although I have seen people with pump carts with an XP motor and then mount a VFD drive on the cart, and the drive and wiring are no way in hell XP, so really seems like a waste of money)
my march pumps are "UL listed", but I know what you mean..... I have another pump designed for pumping seawater to cool AC units on boats, it is sealed for use in the explosive area of a boat hull, so I may see how it works
I may get a eBay XP motor and have the plug and VFD mounted on the wall higher than 3'..... as a bonus, I get variability...
I can see remediating things that are a 'definite' arc source, but other things that are just shielded electrics, like EGK's, I believe there is a higher chance that your gas water heater would explode your house in your lifetime than those things being an ignition source.
Here is the one I was remembering.. it is from the Dalkita preso, they Reference NFPA497
Most of what your talking about is way over my head. However, from a non commercial perspective, for what its worth, if we are talking safety near the still, i think it would be remiss of me not to mention the following.
No matter how strong the urge, DO NOT LIGHT YOUR FARTS!!!
I think it's about being more creative with the approach then just spending big dollars.
You can always mount your VFD in a control box up on the wall, instead of on the cart. Either way you need an extension cord and a place to plug it in. Besides, chances are the pump is going to be somewhere between your mash tun, fermenters, and still, which are probably all in close quarters, so it's not like you need to roll the thing all over.
yep, that is a the plan... I got a 2hp 3phase VFD for $80 and I think some xp motors can be had as low as $50, they are not 'inverter duty', but at 1/10 the price, I can have one fail....
Effective remediation with; air flow/exhaust/turn over in conjunction with knee walls and or complete isolation of the still. Keeping the square foot low, minimizes the HVAC $$$. I've seen this in several well designed distilleries.
A few months ago I made a post about an adjustable adrino module for ethanol vapor detection. It is cheap. One of you smart sparkies could gin up an ethanol vapor alarm in a heartbeat.
I liked grim's design criteria concerning egress and "blow-out deflagration venting roof." I have seen windows setup for blow-out also. Of course that flies in the face of Bonded Areas.
DAD... not yours.. ah, hell... I don't know...
Yeah I played with one of those little guys, they work but I gave up when I realized that calibrating it would be well outside of my ability. Not that I couldn't come up with some number, but I'd never trust myself. I gave up once I realized that companies sell containers of mixed gasses at the specific percentages. I like to geek, but this is outside of my comfort szone.
For $495 the RKI PS-2 is dirt cheap, and can be shipped calibrated with whatever % alarm levels you want, simple wiring to audible alarms, monitored alarm system, or ventilation.
If you want XP, the Beacon 110 is a nice option, but will cost triple when you factor in the sensor.
So while I have yet to explore the vapor explosion issue, since most of the stills a vent to atmosphere then why not set up ventilation to the outside of the building? Having worked around liquid gases and confined spaces I would be more concern about a pressure build with in the still causing an explosion before you were able to fill a room with enough vapor to cause an explosion. But as I say I have yet to research.
The day you quit learning is the day you start dying!
"I am an incurable gadgeteer, and I like enormously to set up a theory and then track down the consequences" Murray Leinster youtube.com/watch?v=08e9k-c91E8
Frankly, I was thinking the same thing. I know of a still building company in Austria that has a reputation (!) of exploding stills, but it had always to do with the pressure inside the bain marie. Considering, that almost all distilleries in Austria run with wood fire, there is happening next to nothing.
What people do without thinking, is another story: there have been some accidents, that were clearly the cause of not using the common sense.
StillDragon Europe - Your StillDragon® Distributor for Europe & the surrounding area
Flame arrestors (FA) and external venting, hazardous zone rating and Ex rated electrical requirements are all well covered in the relevant Australian Standards and should be mandatory for all commercial setups in AU, but it's not. It all comes down to the engineers doing the job and approving the application, since distilleries are relatively new here in AU it's going to take a little time for everyone to catch up.
Easy enough to put a Pressure Release Valve on the still and the jacket (if applicable). Plenty of vendors make them in the single PSI range. 2-3 PSI on the still boiler, and 15 on the jacket.
The outlet of the still boiler PRV is going to need to be treated with some care, as you mention. Needs to release in a manner that doesn't simply trade one serious problem for another.
From my perspective, the highest potential for catastrophe is a vapor leak on the still that is small enough to go undetected, but large enough to emit a significant volume of vapor. Looking back on a number of distillery fires, I suspect this may have been the case in at least 1 or 2, and it had to do with stresses on the piping between the column head and condenser. Easy to miss a leak here where your still is well over your head.
On eBay there is a foreign seller (Taiwan or HK) that sells a flammable gas detector pen that is very reasonable, like $20-30usd. I was tempted to pick one up to be able to do a quick check of the still plumbing on occasion. Gaskets, plumbing, etc. Seems like it would be a relatively easy process, a few minutes into the run, take out the pen, make a pass around the equipment. I would think from a cost and practicality perspective, this is cheap insurance.
Years back I used to run a 2" packed column with a VM/LM combined head. Even then I had the air vent on the reflux condenser plumbed through its own condenser. Drips indicated I was applying too much power for the reflux condenser to cope with and reduced the flamable vapour problem.
Pressure safety valves are a no brainer. Plumbing in the outlet in a safe manner is easy enough. The issue comes more serious when you have solids in the boiler. You need a large diameter outlet to cope with that situation.
A bursting disk in a 2" or 3" line might be appropriate - either that or just avoid the situation.
Having the controls remote from the boiler is easy enough to do and is probably convenient anyway. For a commercial opperation I would have to think really hard to be able to justify NOT using indirect heating. Is remote operation more expensive than EX rated equipment - possibly. Substituting hydraulic or pneumatic motors and valve controls instead of EX rated ones might be an option though.