Tips For Safe Use of LP/Gas Roasters In a Residential Setting

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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TomC
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#1: Post by TomC »

I haven't seen a thread like this here and felt it was important to have, seeing how many of us are broadening our horizons into home coffee roasting with larger, commercial grade LP/Nat Gas roasters. I'm sharing a few tips I've learned as well as some from someone with 20+ years in the industry who's roasted on pretty much every major gas commercial coffee roaster in the industry. Christopher Conover is a moderator of another large online coffee roasting discussion forum with 10 years of sharing his wisdom there with other members as a moderator. The following are some general safety tips when roasting with any fuel burning device. Please by all means, contribute to this thread with any other safety tips you may have and I'll update this first post for easy reference in the future. This thread is not to be considered complete, and they are only generalized safety tips, not legal advice in roasting operations.

Absolute Rule #1 before all other rules: Never leave a gas burning roaster unattended at any time it is running.

2) Never initiate a roasting session without verifying that there's no gas leak. This must be done before every roasting session if safety is (and should be) your primary concern. Use a spray bottle with liquid soap and spray all your valves that are inline from the source to the main supply valve. Once your gas lines are attached and the tank is on, a quick few spritzes takes only an extra second or two and can help ensure a safe working environment.

This is what a small gas leak looks like. Note the fine bubbles between these two brass adapters.





This is what a patent gas line looks like.




If a gas leak is found, turn off the gas supply at the source, all gas valves, check, fix, and recheck for leaks before igniting any roaster.


3) Never initiate a roasting session without understanding and implementing adequate ventilation. Roasting outdoors is wonderful, but often not ideal for many people. If you're roasting in a garage, even with the garage door open, you still need proper ventilation. An ideal roasting area is one that is either outdoors, or in very close proximity to an outdoor, fresh air area where the roaster is still in direct line of sight that you can walk to for fresh air in the case of a CO alarm. Full, complete combustion of hydrocarbons only create a trace amount of CO, but precautions must be taken to ensure safety.

4) A smoke and CO detector should be installed in relatively close proximity to the roasting area. You cannot smell, taste, see or sense CO poisoning. Your sensation of it would only be apparent after a great deal of poisoning has occurred and the stupor it induces can lead to unconsciousness, coma or death. I've treated patients every winter who've suffered CO poisoning and it's not pretty. Killing brain cells from hypoxia is also permanent. Your red blood cells have a 200x greater affinity to carbon monoxide than they do oxygen, meaning they will readily bind with CO preferentially over oxygen. It's not something to take lightly. Ensure tight seals of all ventilation tubing, and monitor your environment at all times. If your CO detector alerts, shut off your main gas supply at the source and the roaster and walk away to a better ventilated space (outdoors) for several minutes for fresh air. Troubleshoot your system in a safe, controlled environment!

5) Never roast without a fire extinguisher within close proximity to your roaster. For a home roaster, on a small machine (1-2 kilo's max), the risk of a large fire necessitating a fire extinguisher is very small if you've observed all your safety steps ahead of time. 90% of all flame-ups on small roasters is coffee chaff that has fallen between the front lip of the drum and faceplate, falling down into the burner area underneath, which readily become glowing embers. These in themselves are generally self extinguishing, but if a person was negligent in their routine cleaning of the roaster, some chaff build up can start a small fire. In this instance, only on these small roasters, a large water filled spray bottle is a better choice over a chemical fire extinguisher. If you see a small fire, turn off your gas supply and use the spray bottle to quickly extinguish these small flames. These fires don't need a large chemical based fire extinguisher, and using a chemical fire extinguisher means you get to tear your whole roaster, drum included, apart for heavy, difficult and laborious cleaning or your roasts will have a wonderful flavor addition that you do not want. Many of these small chaff fires are self extinguishing flashes as they quickly become hot embers then ash almost instantaneously.

6) Read and understand how to operate your chemical fire extinguisher before starting the journey of an amateur roaster. Verify that your extinguisher is fully charged and that it hasn't expired (some are tagged with 'expiration' dates.

7) Roast in a well lit environment with few distractions. If roasting alone, be aware that you're managing two jobs at the exact same time, that of roastmaster and safety officer. Do not take shortcuts in your safety.

8 ) Routine maintenance is required for any roaster. Once the transition from small scale electric roasters to gas roasters begins, so does the risk factor. It's not worth burning down your dwelling, or risking personal injury, keep your gear clean and you'll avoid a large majority of the problems before they can start! Exhaust tubes, chaff trays (main and under cooling tray) should be cleaned frequently. Ensure that the area under the drum with your burners is clean and chaff free.

9) Know your roaster inside and out before modifying anything. Modifying a stock gas roaster at home to include profiling/PID devices should only be done with extreme caution. A common risk for modified PID'd roasters are thermocouple failure. Christopher described a situation where his BT thermocouple began to give erratic values of 450°F to suddenly dropping to -180°F briefly. This was due to over flexion of the thermocouple shaft leading to breakage and intermittent failure. In this case, if the controller on the roaster thinks that the temp is only '-180°F' (impossible), then it's going to far exceed its safety cut off and the temps can possibly climb to dangerous levels. If your cutoff is set for 460°F, and your controller thinks its only -180°F, you've got a problem if you're not closely monitoring gas pressure, flame, and actual environment temps. An analogue ET is a good idea as a secondary temp monitoring device.

10) Your propane tank (if using a bottle) should be properly secured, sitting in on a stable surface, preferably on the ground or not where it may be at risk of falling over.

Additional tips:

Use stainless steel for exhaust ducting. Thin Aluminum duct will quickly fail in the event of a fire. I had a local sheet metal shop make a stainless steel panel that replaced my fireplace door creating a completely contained area to duct into. This also provided better consistency in the roasting process compared to ducting directly outdoors with the variances in wind/atmospheric pressure changes that occurred at the exhaust outlet.

Feel free to add to this list. Safe roasting!

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tamarian

#2: Post by tamarian »

Really good post, and well needed. Thanks for taking the time and posting it.

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hankua
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#3: Post by hankua »

Great reference post!
I've got the fire extinguisher but no water bottle.
My only suggestion would be to bold some important titles/ fire & health risks.

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TomC
Team HB

#4: Post by TomC »

Good idea. I had meant to do that and started with a few underlining, but ended up getting distracted doing some editing for typos.

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danetrainer

#5: Post by danetrainer »

Here are a few items that I would like to add to this topic since gas powered roasters are becoming more popular & available to the home roasting crowd. I've been using my 2 Kilo propane roaster indoors since 2009, and safety is definitely a top priority. Several of these suggestions are a repeat of Tom's initial post for emphasis.

Never leave a powered up roaster unattended. Visually inspect all piping, electrical, & controls before starting.

Never use a spliced together gas line like the one in the photo above (the one used to display gas leakage). Screw type hose clamps do not provide equal pressure around the hose due to their design; a professional swage crimp fitting is the only safe design for flexible connections. A "custom" professionally made hose can be designed and obtained in nearly every locality. Eliminate as many "adapters" as possible, thus minimizing the number of areas the propane or natural gas may leak from. Always test connections.

Use stainless steel for exhaust ducting. Thin Aluminum duct will quickly fail in the event of a fire. I had a local sheet metal shop make a stainless steel panel that replaced my fireplace door creating a completely contained area to duct into. This also provided better consistency in the roasting process compared to ducting directly outdoors with the variances in wind/atmospheric pressure changes that occurred at the exhaust outlet.

I devised my own solution to avoid using a "chemical" fire extinguisher (knowing the destructive residue that would be left behind) required two options. You need an ABC type extinguisher to fight a possible roaster fire. I purchased a 5lb CO2 extinguisher that is rated for BC type fires and I have a pump up garden sprayer filled with water. The BC extinguisher is designed for use on flammable liquids & electrical fires. Type A is used on wood, paper, cardboard...ie: cellulose (beans & chaff). Although the type BC could put this type of fire out it creates the hazard of spreading the cellulose materials allowing them to reignite when enough oxygen was present again. If the materials remain "contained" they will be extinguished with the CO2 inert gas. Understanding the source of ignition, knowledge, & fire fighting technique are key here...

Finally, keep the roaster clean, I always vacuum chaff from the areas it collects before using my roaster. The ducts, fan & passageways need to have residue removed periodically according to the amount of usage. I keep a log on the inside door of my roaster with the date I last cleaned it.

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LDT

#6: Post by LDT »

I am curious as to how many using propane fuel leave the cylinder inside the home (basement or garage)? I have, but I am not comfortable doing so.

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Randy G.

#7: Post by Randy G. »

- Use a long enough supply line so that the tank (if used) can be located away from the roaster during use. This way the shut off valve can be reached in an emergency. If there is a roaster fire you do not want the tank near the roaster.

- Locate the extinguisher near the safe exit. Always fight a fire with an exit to your back and the fire in front of you.
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Boldjava

#8: Post by Boldjava »

LDT wrote:I am curious as to how many using propane fuel leave the cylinder inside the home (basement or garage)? I have, but I am not comfortable doing so.
Before he retired, my brother worked as the lead design and manufacturing engineer for one of NAmer's largest scuba and propane valve manufacturers. I related other homeroasters use of tanks within homes. His advice to me was simple: don't do it. The advice from all propane distributors? Don't have a tank within the home. The advice from every state regulatory authority on the same issue? Don't do it.

I hope to have a drum roaster within the next two years. I will have a line plumbed.
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TomC
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#9: Post by TomC »

It's a challenge either way. If you have a problem, you are farther away from the bottle to shut it off. If you have it close, leaks can prove disasterous.

I know Henry and Dustin both roast with their tanks within a short 3-4 feet from their roasters. I have a custom made 5 foot line. I will practice dilligent leak testing before each roasting session, but I want to be able to immediately kill my gas supply at the source, not just at the valves within the roaster. I imagine strong arguments can be made either way though.

I wouldn't store the propane indoors when not in use though and have set up a clean, covered spot for it outdoors. I also have pure oxygen and compressed CO2 for beer brewing and yeast propagation that I've since completely relocated. I don't want an oxygen tank anywhere near a fuel source.

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LDT

#10: Post by LDT »

With the Huky 500, the supply line is attached with clamps to the regulator on one end and the burner on the other. To store outside without loosening and re-attaching the gas line clamps involves storing the tank, line and burner outside. I suppose a quick disconnect could be used at some point in the supply line, but again that involves introducing another leak source.

Having a line properly plumbed in is the best solution, but that means your roasting location is fixed. At this point I have not decided on a permanent location for the roaster. By the way, thanks for starting this topic. For some it may be way more important than just concentrating on the best roasting profile.