Moth cannot be stopped
1. CO2 puts out fires, it doesn't blow up 2. It might fill the space with CO which is a deadly gas. If the garage has a lot of drafts, the flow of air can keep the CO from reaching deadly levels. 3. If all else fails, get a ton of life insurance on him.

Uncle
Propane is heavier than air which is heavier than natural gas. Both natural gas and propane will dissipate into the air if they are released in an open enough environment and both can pose an explosive risk if they concentrate enough and are ignited. However, because propane is heavier, it tends to fall to the ground, collect, and pose a greater explosive risk. On the other hand, because natural gas is lighter than air, it tends to rise and dissipate into the air, posing less of an explosive risk. it should never be stored indoors or with 10ft of any building

ahsoasho2u2
Propane Natural gas Acetylene CO 2 All are used for welding.

Dad first time
Check the instructions or any labels probably wear it may say WARNING ! And then after that you will know,

Propane Guy
Any propane burning appliance requires two types of air. Combustion air and ventilation air. You need to have enough air there for the appliance to mix with fuel and have complete combustion of that mixture. When this happens, the products of combustion are carbon dioxide and water vapour. You need to also have sufficient ventilation air to allow the products of combustion to escape. If you do not do that and reburn those gases you will be making carbon monoxide which as you probably already know is a poisonous gas. The manufacturer's CERTIFIED operating instructions will list the air requirements for that particular appliance. The general rule of thumb we use in the industry is one(1) square inch for every one thousand(1000) btu's. So if you look at the appliance and find that the rating plate states an output of 30,000 btu's, you will need a fresh air opening of at least 30 square inches to provide adequate air for combustion and ventilation. I know that sounds like a lot, but it is what you need to have for safe operation. Hope this helps!