Blends of Biodiesel are similar to blends of Ethanol only for the fact you can tell what percentage of the product is actually Biodiesel and how much is Highway grade (D2) Diesel.
B20 is 20% biodiesel fuel, and 80% No. 2 diesel.
B40 is 40% biodiesel fuel, and 60% No. 2 diesel.
B100 is 100% biodiesel fuel with nothing else added

Homebrew Biodiesel Fire
Posted December 9th, 2006 by Kai Curry
On May 7, 2006, a hazardous materials (HazMat) release occurred in a residential area of Colorado when a homeowner who was processing a tank of homemade biodiesel fuel forgot to turn off the tank's heating element and left for the weekend.
The heating element overheated and caused a fire that burned the surrounding shed and equipment.
The shed had contained >600 gallons of biodiesel and recycled restaurant cooking oil, smaller amounts of glycerin and sodium hydroxide, and 1-gallon containers of sulfuric and phosphoric acid; a mixture of these ingredients seeped into the ground during the fire.
A certified HazMat team and the local fire department responded. Investigators found seven 55-gallon barrels of methanol and other hazardous materials outside the shed. No injuries or evacuations occurred. To prevent potential injuries, biodiesel should be purchased from a licensed commercial source.

Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl (methyl, propyl or ethyl) esters. Biodiesel is typically made by chemically reacting lipids (e.g., vegetable oil, animal fat (tallow)) with an alcohol. Biodiesel can also be made from algae.

During production a byproduct of glycerin is produced. While glycerin does not have any specific flammability concerns and is used in several safe products, burning of glycerin produces a by product of Acrolein among several other substances. 
Acrolein is a severe pulmonary irritant and has been used as a chemical weapon during World War I. Skin exposure to acrolein causes serious damage. Acrolein concentrations of 2 ppm are immediately harmful and a suspected human carcinogen. "Where is the waste glycerin stored?"
"One pound of glycerin is produced for every 10 pounds of biodiesel," said Gonzalez, Rice's William Akers Assistant Professor in Chemical and Biomolecular Engineering.

One concern of biodiesel is when "home kitchens" and small or larger scale production in garages, barns etc. may yield storage in drums or other larger tanks along with waste products.

Click here for a website with more information on Biodiesel

Expect storage of:
Methanol (1230,...DOT guide 131)..or..
Ethanol (1170,...DOT guide 127)
Potassium Hydroxide (1813,...DOT guide 154)..or..
Sodium Hydroxide (1823,...DOT guide154)
Sodium Methoxide (During a process)
Sulfuric Acid (1830,...DOT guide137)
Phosphoric acid (1805,...DOT guide154)
Oils such as rapeseed, canola, corn, soy or sunflower oil, and commercial oils in general "Combustible liquid, n.o.s. (1993,...DOT guide128)
Diesel fuel (for making B20, B80 etc.) (1993,...DOT guide128)
Biodiesel containers (jugs, drums etc.)
Waste products (such as glycerin)

Although there are a variety of manufacturing processes

Example of a biodiesel kit available on the internet