The only safe way to put out a propane or city gas fire is to turn off the gas. If you put the fire out and don't stop the gas flow quickly, it will find another ignition source and re-light, possibly causing a bigger fire and/or explosion in the process. You don't want to be there when this happens. Control the fire so nothing else burns, but don't put it out.
Purple K fire extinguishers are intended for burning metal fires. They are expensive, and not very good at fighting any other kind of fire. We carried 1 Purple K extinguisher on each engine, and used them mostly when we had a VW hatchback engine fire, because the fan part of the engine was made from magnesium and was very difficult to put out any other way. Many times it was necessary to chop out the burning metal and bury it to put it out because even the Purple K didn't work well enough, and at least two engines responded to every auto accident or vehicle fire, one of them being a tanker/pumper, so we brought over 2,500 gallons of water with us, and at least two Purple K extinguishers.
Fire Classifications -
A = burning wood and paper
B = burning liquids
C = burning electrical fires (best to turn off electrical source first, in which case it
becomes more of a class B fire)
D = Burning metal
Carbon Dioxide fire extinguishers are great for class B and C fires, but they are heavy. Their one big advantage is that they don't make a mess like dry chemical extinguishers do.
Water is a great class A fire extinguisher.
When using a fire extinguisher, get as close as you can to the fire and use the extinguisher to sweep the fire off of the burning material much like you would use a push broom. Be careful not to allow it to sneak back around either side as you advance, and continue until the fire is completely out. Then back away carefully until you are safely out of the involved area. Fires can re-light, so be prepared not to allow it to get behind you as you back away.
Don't keep your fire extinguisher right next to the most probable sources of fire. Locate it near your exit point.
That way, as you are running away from the fire, you can decide to turn and fight the fire with the fire extinguisher, or decide that it's too big to fight and continue running away, hopefully toward a phone or alarm call box to get help. A fire extinguisher that is located close to the likely fire source could be in the fire, and it will do you no good, since it won't fight the fire without you operating it.
An untrained person will not operate a fire extinguisher correctly, so their chances of successfully putting a fire out by using a small fire extinguisher, like the 2 1/2 lb in the photo above, because they will waste most of the few seconds that the extinguisher will deliver the extinguishing agent. They will spray it at the fire and smoke rather than at the base of the fire, or they will begin shooting the extinguisher from too far away for it to be effective. If used properly and under all of the right conditions, that 2 1/2 lb dry chemical extinguisher can put out a fire in a trash can and not much larger. If it's a bigger fire than that, your chances will be significantly reduced, especially if you have had no experience using a fire extinguisher.
I have two 10 lb dry chemical ABC extinguishers and one 20 lb CO2 extinguisher in my shop, all located next to the exit doors. I also have a water faucet and a 50' garden hose and nozzle on the outside of the shop between the exits. The nearest manned fire station to my home and shop is also only 2 1/2 miles away. My kitchen has a 10 lb ABC dry chemical located in it near the door, and my garage has a 10 lb dry chemical ABC plus a 20 lb CO2 extinguisher located just inside and between the two garage doors. There is also a pressurized water extinguisher in both the first and second floor hallways.
I was a volunteer fireman from the age of 18, working my way up to Captain of a 6 vehicle fire company. For my last 7 years, before my first retirement at the age of 58, I was the fire marshal for a 3.8 million sq ft manufacturing facility located on 1,364 acres. I managed 5 fire technicians who maintained and tested all of the fire equipment in the facility.
I have a deep respect for fire, and the damage that it can do. I've probably a bit over protected my family, home, and shop, but I feel comfortable in the fact that I have fire extinguishers placed near my family and me, so we can minimize any fire damage to our property until help arrives. The farther you are away from your nearest fire company, the more protection that you should have because you won't likely have any help for at least 5 minutes and in rural areas this could be 35 minutes or more. I've arrived at structure fires before the trucks have arrived and made significant progress using only a garden hose, or even snow to fight the fire, until the trucks got there.
Central North Carolina