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

1. 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.

2. A dual-stage fire suppressant system according to claim 1 , wherein the first heat sensitive pressure tube is further configured to:

be filled with a gas and held under a first pressure;

rupture in response to an applied heat load causing the gas to exceed a predetermined threshold, wherein the rupture causes a pressure loss creating the fire detection signal; and

distribute the first fire suppressant agent released from the first housing.

3. A dual-stage fire suppressant system according to claim 1 , wherein the second heat sensitive pressure tube is further configured to:

be pressurized with the second gas substantially simultaneously with the second housing;

rupture in response to an applied heat load to create the second fire detection signal; and

distribute the second fire suppressant agent released from the second housing.

4. A dual-stage fire suppressant system according to claim 3 , wherein the second heat sensitive tube is configured to rupture in response to the second gas to exceeding a predetermined threshold.

5. A dual-stage fire suppressant system according to claim 1 , wherein the second valve further comprises a sealed pressure vessel containing a compressed gas, wherein the pressure vessel is configured to release the compressed gas into the second housing and the second heat sensitive pressure tube in response to the detection of the released first fire suppressant at the second end of the pneumatic tube to thereby pressurize the second housing.

6. A dual-stage fire suppressant system according to claim 5 , wherein the pressure vessel comprises at least one of a gas cartridge and a burst disc.

7. A dual-stage fire suppressant system according to claim 5 , wherein the second valve is further configured to compromise the integrity of the pressure vessel to facilitate the release of the compressed gas into the second housing.