This organization is looking for a simple solution that can use a passive sensing method to automatically detect and extinguish a fire in power/communication cables arrayed in a cable tray.

Such fires can be caused by an over-current condition of the cables in the tray. These trays are covered by a fire retardant sheet, but this does not extinguish the fire.

The insulation material of the cable is a cross-linked polyethylene or similar. The exterior cable sheath is made of flame-retardant vinyl, or a similar material.

The client believes that when a cable experiences an over-current condition, it heats the cable and thermally decomposes the inner insulating material, which emits flammable gas, triggering the fire.

Background:

It is necessary to extinguish a cable tray fire immediately. Cable tray installations are widespread, in power plants, in factories, and in communications facilities.

Cable trays in these facilities may extend for as long as 2km (both horizontally and vertically). Typical tray size is 1m x 0.3m x 2,000m, for a total volume of 600m3.

Fire suppression may need to take place over the entire length of the tray run.

There are systems that detect fires in cable trays and that spray extinguishing agents.

However, such systems are highly complex and designed for large-scale applications.

For this reason, the client is looking for a simpler and more passive fire-extinguishing approach that still is able to handle the required tray length and volume.

Constraints:

Desirable conditions are as follows:

  • Effectively detect the fire location and automatically extinguish the fire in the limited area where it occurred
  • Detect abnormal temperature, flame, or smoke and initiate fire extinguishing activities automatically. Such systems must work under power-outage conditions, so the proposed system should not require a power supply
  • The proposed system should release its extinguishing agent (such as foam) into the full run of the cable tray, because an over-current cable is likely to burn over its entire length
  • The operation of the automatic fire extinguishing equipment must be able to be confirmed at a remote location such as a central control room. (This function need not be a part of the passive fire extinguishing system)
  • Requirement for extinguishing agent:
  • Not harmful to humans
  • Should have insulation properties in order to minimize negative effects on other electrical equipment in case of malfunction.

Comments:

Development support may be provided depending on the stage of development.

Possible solution areas:

  • Heat-sensing automatic fire extinguishers
  • Heat-sensing carbon dioxide gas foaming
  • Thermal expansion insulation rubber

Desired Outcome:
It is desirable to have;

  • a simple system,
  • a smaller number of installation units,
  • a system with easy maintenance and checking. The client would like to install such systems at the beginning of 2017.

Previously Attempted Solutions:              

So far, the client has considered the following techniques, but each has its own issue with implementation:

  • Heat-sensing automatic fire extinguisher (issue: size of the fire extinguisher, explosion due to malfunction)
  • Tube-type heat sensing automatic fire extinguishing system (Issue: large scale system for the entire cable tray)
  • Heat sensing carbon dioxide gas foaming (Issue: Sufficient amount of carbon dioxide gas may not be dissolved in water. It may not generate a sufficient amount of CO2)
  • Thermal expansion insulation rubber (Issue: enough sealing of the tray, weight, etc.)
  • Extinguishing liquid scattering-type automatic fire extinguisher due to thermal rupture (Issue: safety of container material)

Desired Timeframe: Within 12 months

Company Type: Commercial (Publicly Held)

Annual Revenue: More Than $500 Million

Field of Use and Intended Application: On-demand fire extinguishing for power/communications cables in cable tray

Licensing Terms:

The listing client (the TechNeed author) has agreed to pay any yet2.com success fees should a deal result from introductions to this TechNeed.