Methods and apparatus for passive non-electrical dual stage fire suppression

A dual-stage fire suppressant system for protecting a surrounding environment from a fire, comprising:

• a first fire suppression unit comprising:
• a first housing configured to contain a first fire suppression agent;
• a first valve connected to the first housing and configured to:
• maintain the first fire suppressant agent under pressure in the first housing;
• release the pressure in the first vessel to distribute the first fire suppression agent in response to a fire detection signal;
• and
• a first heat sensitive pressure tube connected to the first valve, wherein the first heat sensitive pressure tube is configured to create the fire detection signal in response to an applied heat load;
• a pneumatic tube having a first end connected to the first valve, wherein the pneumatic tube is configured to route a portion of the released first fire suppressant from the first end to a second end of the pneumatic tube;
• and
• a second fire suppression unit linked to the first fire suppression unit, wherein the second fire suppression unit comprises:
• a second housing containing a second fire suppression agent;
• a second valve connected to the second housing and the second end of the pneumatic tube, wherein the second valve is configured to:
• pressurize the second housing with a second gas in response to a detection of the released first fire suppressant at the second end of the pneumatic tube;
• and
• release the pressure in the second housing to distribute the first fire suppression agent in response to a second fire detection signal;
• and
• a second heat sensitive pressure tube connected to the second valve, wherein the second heat sensitive pressure tube is configured to create the second fire detection signal.