http://www.tsa.gov/travelers/airtravel/prohibited/permitted-prohibited-items.shtm

 scroll down to "disabling chemicals..."

Disabling Chemicals & Other Dangerous Items Carry-on Checked
Chlorine for Pools and Spas No No
Small compressed gas cartridges
(Up to 2 in life vests and 2 spares. The spares must accompany the life vests and presented as one unit)		 Yes Yes