I actually have witnessed an entire cremation, but the story behind how I ended up there is quite comical.
I ride Honda Scooters (not the small ones, the big ones 250 cc's), I was going down a road in Sacramento looking for a futon shop and I figured I was lost. I pulled into this long driveway of what looked like a house. As I pulled around the back I noticed that the garage was open and there was a gurney with what looked like a mummy on it.
There is no reverse on a motorcycle so you have to push your bike back to turn around and as I was doing that I noticed that a guy came and pushed the gurney to this large pizza oven looking like thing. He popped open the door and took a paddle and pushed the mummy into the oven. Slammed the door shut, pushed some buttons and came over to help me out.
I was in a state of shock. I didn't know what that place was. He thought I was there for a body pick up and when he discovered I was simply lost he started to laugh. He wondered how I was going to haul around dead weight on my scooter.
I asked him what the mummy was and he told me that he was cremating someone. What really shocked me is that the building looked like a house and it was right smack in the middle of a residential neighborhood. He invited me in to look around. I couldn't resist. Should me the cooler area where they keep people, took me to where people are wrapped like mummies, even let me look into the peep hole in the retort so I could see the afterburner work.
The cremation took about an hour, she was a small woman with cancer. He cleaned out the retort, let me watch that process and then showed me how he processed the remains. I do want to say that when he opened the retort door that there will still flames coming from the bones, it was because the marrow hadn't completely burned.
Me, I want to be recycled as rice at someone's wedding!
Although not stories exactly these are accounts from the Yahoo Cremation Group written by cremation professionals about how they carry out cremations.
From Las Vegas USA...
"The crematory I run is on the property of a funeral home amd
cemetary so transfer of the deceased is easy and quick. The deceased is placed in an Alternative Cremation Container (cardboard box) or is in a casket (after a funeral or viewing).
The equipment is heated to 1400+ degrees (Fahrenheit) and the deceased placed inside. The machine is semi automatic in regard to temperature control. It will cycle
between 1588 and 1634 degrees for 150 minutes. After approximately two minutes I turn on the actual cremation burner. This is the flame that actually makes contact with the
body. During the 150 minutes the "throat air" at the back of the unit is on maintaining the temperature in the after chamber. After 85 minutes the throat air turns off.
After another 20 minutes the "hearth air" turns on (this like a bellows on a fireplace). Generally the cremation is completed after 125 minutes.
After the cremation is completed, there is a cooling off period. the unit must be cooled to approximately 750 degrees before I can remove the cremated remains. This is accomplished with a long handled wire broom and a shorter handled one. I then vacuum the unit out removing as much of the remains as possible. (***** Note --- most crematories do not vacuum the retort out, this is required by our corporation in the western US.) The remains are then processed in a pulverizer down to a fine powder and then are placed in the container chosen by the family.
Now a very large person (350+ lbs) or a casket changes the timing of the cremation - as this changes the amount of heat produced by the body. We humans generally produce 14,000 BTUs per pound of body."
The equipment described in this piece is a Power Pak 2 from Matthews - shown in the image
From Ontario Canada...
"The ones I used to run had a different procedure. The postcombustion chamber
which occupies the space under the hearth is preheated to 850C (centigrade) and the main chamber to about 500C. The casket is then charged into the cremator and it should ignite as
it slides in on its own from radiant heat in the hearth floor. Airjets in the side wall are slowly turned on and the amount of air is increased to maintain a steady rise in
temperature, while watching the stack to ensure that it doesn't start to burn so fast that the post combustion chamber becomes pressurized and smoke starts to billow out of the stack.
The biggest rise in temperature and risk of smoke is when the casket breaks open. When you reach a main chamber temperature of about 1000C one just adds air to maintain it
After about 40 minutes the main chamber temperature will start to drop, and often the remains that are left - usually the spinal column - are repositioned with the rake to be under the main ceiling burner that is then turned on. In about 10 minutes it is turned off and the rake is used to push the remains to the back of the hearth where there is a large hole that is the exit for the smoke into the post combustion chamber. The remains are pushed down it and they fall in front of the afterburner where any charcoal is burned out and final calcination occurs.
A steel wire brush is used to sweep the hearth and the next case is loaded with the main chamber sitting at around 700C, so it will ignite on its own and the process starts all over again. About halfway through the second cremation the remains from the post combustion chamber are swept out into a pan to cool and then ground down."
The cremator described above was a Foster Westminster. The image is the newly bricked chamber of a B and L machine, but this machine works in a similar way.