About Gases:

1. Gases, referred to flammable gases generally, that are colorless, odorless, tasteless, and non-toxic. An artificaial smell added to gases is the source of the odor.
2. Liquefied Natural Gas (LNG), also called Natural Gas (NG), is primarily composed of methane.
3. NG is lighter than air, so it will disperse into the atmosphere.
4. Liquefied Petroleum Gas (LPG), also called propane tank or LPG tank, is primarily composed of propane and butane.
5. LPG gas (vapor) is heavier than air, so it will settle when leaking indoors.
6. Gas explosions can occur when gases are exposed to an ignition source such as heat or fire.
   (Check the following chart about carbon monoxide (CO).)

學名	英文名稱	化學式	爆炸下限	比重(空氣=1)
甲烷	Methane	CH4	5%	0.55
丙烷	Propane	C3H8	2.1%	1.56
丁烷	Butane	C4H10	1.9%	2.01
異丁烷	Isobutane	C4H10	1.8%	2.01

二、認識一氧化碳：

1. 一氧化碳(簡稱CO)，是無色、無味和無臭的毒性氣體。
2. 低濃度的一氧化碳，長期暴露就會頭痛、噁心、疲倦感。
3. 高濃度時抽蓄、無意識，嚴重者1~3分鐘立即死亡。
4. 一氧化碳比空氣輕，很容易飄入室內。

暴露時間對人體的影響

一氧化碳濃度	暴露時間對人體的影響
50PPM	一般而言8小時內尚無徵狀。(OSHA*最大允許暴露條件)
200PPM	2~3小時內輕微頭痛、噁心、疲倦感、暈眩。
400PPM	1~2小時內劇烈頭痛、噁心、疲倦感、頭暈。
800PPM	45分內噁心，抽搐，2小時內無意識，2~3小時內可能死亡。
1600PPM	20分內頭痛、噁心、無意識，1小時內可能死亡。
3200PPM	5~10分內頭痛、噁心、無意識，25~30分內可能死亡。
6400PPM	1~2分內頭痛、噁心、無意識，大約在30分鐘之內死亡。
12800PPM	1~3分內立即死亡。