Liferafts have a bad reputation for not always inflating. I was glad to watch my raft successfully inflate, then dismayed at the continuing hiss of air out of what I thought was a manual inflation valve. The air was actually from an overpressure valve, as the CO2 cannister is apparantly larger than necessary to inflate the raft at room temperatures, so the raft vents the excess air out. After a couple of minutes, all the noise stopped, and the liferaft remained inflated.