How Does the 170°C Thermal Sensor Cord Activate the Unit Autonomously?

One of the biggest advantages of modern aerosol fire suppression systems is their ability to operate without external power. Traditional active fire protection systems require 24/7 electrical supplies, backup batteries, smoke detectors, and control panels to initiate discharge.

CSI Afex devices use a specialized thermal sensor cord (thermal linear actuator) that triggers the suppression unit autonomously. In this article, we explain the science behind this thermal cord, how it detects localized heat, and the mechanical-chemical pathway it uses to extinguish fires.

1. The Structure of the Thermal Sensor Cord

The thermal sensor cord is not a typical electrical cable. Instead, it is a fast-burning pyrotechnic cord containing a proprietary chemical formulation cores wrapped in glass fiber and protective braiding.

It is designed to activate when exposed to a specific temperature threshold of 170°C (±5°C). This temperature indicates an active electrical fire, such as overloaded cables or short-circuiting MCB components, but remains high enough to prevent accidental triggers from normal cabinet operating temperatures.

2. The Chemistry of Autonomous Activation

The self-activation sequence occurs rapidly and relies on basic chemical physics:

1. Thermal Exposure: An electrical fault generates heat. If local temperatures on cable bundles or busbars reach 170°C, the thermal cord reacts.
2. Linear Propagation: The chemical core ignites at the contact point. This ignition creates a rapid, self-sustaining burn that travels along the cord at a rate of several meters per second.
3. Solid Chemical Igniter Trigger: Once the burn path reaches the connection socket inside the CSI Afex unit, the thermal signal strikes the internal solid chemical igniter.
4. Aerosol Generation: The igniter triggers an endothermic reaction within the main potassium compound block. The solid block turns into a dense, rapid-fire extinguishing gas in under 3 seconds.

3. Serpentine Routing and Cable Layering

To ensure rapid detection, correct installation is key. As a certified distributor aerosol fire suppression Indonesia, PT Parama Energi Raya follows strict installation guidelines:

• Serpentine Laying: The cord is routed in a wave-like pattern across all high-risk areas—weaving through main input lines, circuit breakers, and contacts.
• Proximity: The cord should be tied directly to cable bundles using fire-resistant cable ties.
• Avoid Sharp Bends: The bend radius of the thermal cord must not exceed 90 degrees to ensure the combustion front travels smoothly without physical interruption.

Conclusion

The 170°C thermal sensor cord represents a major step forward in fail-safe engineering. It removes complex electronics from the primary detection loop, making the fire suppression system immune to electrical failure, EMI interference, and power loss.