Just as an opening thought, this topic is aimed at raising safety awareness (especially for people who are totally new to coffee roasting). For the old-timers, your experiences as coffee roasters and Aillio’s thoughts are most welcome in this thread.
This is a topic that is sometimes not discussed with home roaster equipment in user forums. It is a well known safety requirement with commercial coffee roasters and those in that biz. Even for “home-roasters”, it is important that you know what you will do in the event of a roaster fire. Many of us roast indoors in our homes, basements, garages, out-buildings, etc. The old adage “an ounce of prevention is worth a pound of cure” comes to mind here.
If you think it is unlikely that you could have a fire in your roaster consider what happened to me many years ago (when I was a newbie). Basically, I had a roaster fire in a 1/2lb Drum Coffee Roaster and had not known that roasted coffee would burn (very well). Imagine roasting as normal, reaching the end of the roast when bean temps are at their highest and suddenly you lose power. Power outages are something that we don’t control from the power company. There is also the possibility of an electronic failure in our roaster that stops the operation and sets up the same scenario.
In my case, it was a power outage from the Power Company in my area. The beans in the drum were no longer spinning, no exhaust fan running and within a few minutes I had a fire in the roaster. That particular roaster had plenty of air inlets to feed the fire. I witnessed how well coffee beans will burn when they have reached a temp of ~497F. Chaff also burns very easily, so keeping the Chaff Collector properly emptied is equally important. By the time I realized that my un-powered roast was increasing in temperature, carbonizing and reached a flash point, I had flames inside the roasting drum. If I’d had just a simple plant spray water bottle at hand, I could have cooled the roast right after having lost power.
I learned a very valuable lesson that day. I was fortunate that I got the fire under control and observed that coffee can burn quite well. Today, with my Bullet, I have a large spray bottle with water at the ready in case I ever need it. My plan would be to unplug the roaster and quench the fire with my water spray bottle. I also have a Type A, B, C fire extinguisher (if needed as a backup) within easy reach near where I roast.
The Bullet is a fairly closed unit with exception to the charge inlet, exhaust outlet and drop door. I don’t know how well it would do at limiting oxygen to a fire and do understand that a fire needs oxygen to burn. If Aillio has done testing on this subject, I’d love to hear what they know/advise too. If you have ever felt that the “dead man’s alarm” on the Bullet (aka error message “A-02”) is a bother, just remember that it has a very useful purpose. Think unexpected distraction (while roasting) or maybe a health problem where the Aillio’s ability to shut down the roast for you could be a life saver.
Here’s a blog post from Scott Rao on this topic that was primarily aimed at commercial roasting, but also has some good points on the subject.
I hope this thread will at least help new roasters. Enjoy your roaster and at the same time be prepared in the event of a problem.