A Fire Suppression System Failure?

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Expertise Includes:

    • Electrical & Mechanical Control Systems
    • Fires & Explosions
    • Gas Fired Equipment & Appliances
    • ICC, NFPA, OSHA Codes & Standards
    • Industrial Processes & Operations

Yachts are equipped with fire protection systems to prevent extensive damage, protect lives and ensure safety. However, in order for these systems to be fully effective, they must be properly designed, installed, inspected and maintained.

When a fire occurred in the engine room of a yacht under power at sea off the coast of Florida, the engine room’s fire suppression system did not activate. I was retained on behalf of the yacht manufacturer to conduct an engineering investigation and to determine if a condition of defect in the fire suppression system equipment or installation prevented the system from activating.

The engine room’s fire suppression system had provisions for manual and automatic actuation. The manual actuation could be accomplished at either the local suppressant storage cylinder or at a manual pull station located next to the engine room entrance door. Automatic actuation could be accomplished via a pneumatic fire detection system that incorporated a pressure-sensitive CO2 control head valve and two heat-activated detectors (HADs).

A composite view of the port sidewall of the engine room, where the fire began.

An analysis of the engine room showed a high probability that nearby combustibles had been ignited by the port engine exhaust pipe. Heat from the resultant fire spread in the engine room and affected the room’s contents to varying degrees. The upper area of the room where the HADs were located was subjected to elevated temperatures and yet the fire suppression system did not activate. Normally, the rate of rise in temperature would cause pressurization of the HADs and the pneumatic circuit, and trigger the CO2 actuating head.

A sagging, melted light lens is seen next to a heat-activated detector.

What prevented the system from detecting this fire? There were three possible reasons identified:

1. Insufficient rate of temperature rise at the subject detector locations.
I had proof this was not the case. Recorded engine room data showed a temperature rise at the time of the fire that should have actuated the system. In fact, nearby plastic lighting lenses were sagged and semi-melted, indicating the HADs were exposed to significant levels of heating. The rate of rise and duration should have been sufficient to activate the system.

2. Failure of the CO2 actuating head to sense the rise in pressure in the pneumatic detection system?
According to several examinations — both before and after the fire — the CO2 actuating head was capable of activating. It would be unusual for the system to have a working actuating head before and after the fire, but fail during the fire. In this case, however, if the actuating head was exposed to considerable heat during the fire — and it was — the actuation point could have been affected. The potential for the fire to have affected the actuation head could not be entirely dismissed, although this method of system failure was considered unlikely.

3. Leak in the pneumatic detection system?
A leak in the pneumatic sensing system will also prevent sufficient buildup of pressure in the detection system and prevent actuation. The system in this case is known to be free from gross leakage, proven through heat gun testing before and after the fire.  A heat gun is essentially a very high temperature blow dryer. The very high rates of temperature rise from heat gun testing will detect gross leakage, however not necessarily smaller leaks. A small leak in the pneumatic detection system could have existed and prevented the system from actuating.

The manufacturer’s instructions outlined a testing procedure that would have found even very small leaks. The installing contractor had failed to utilize this procedure, despite the manufacturers recommendations and the requirement of NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems to “Check pneumatic equipment, where required, for integrity to ensure proper operation.” Additionally, the forensic engineers who initially examined the system also failed to properly check for leaks, then dismantled the system, preventing me from ever knowing with certainty the pneumatic integrity of the system.

Because the system had been improperly examined and dismantled before my involvement, I was unable to determine with certainty the reason the system did not discharge. However, I was able to determine the system installer should have detected a leak at installation if there was one present, but failed to conduct the specified tests to ensure a leak free installation. This despite their certification the system had been installed “in accordance with NFPA, the manufacturers and USCG recommendations.”

John Holecek, senior consulting engineer at Warren, is a licensed professional engineer in South Carolina, North Carolina, Alabama, Florida, Georgia, Ohio and Virginia and has both a Bachelor of Science in Mechanical Engineering and Master of Science in Mechanical Engineering from the University of South Carolina. A certified fire and explosion investigator by the National Association of Fire Investigators, John has more than 22 years experience in the design of industrial process equipment and is extremely knowledgeable in ICC, NFPA and OSHA codes and standards. He pairs more than 13 years of experience supervising manufacturing operations with deep knowledge in areas such as applied industrial heat transfer in oven design, industrial electrical process and motor control systems, material handling systems and fire protection systems. In addition he’s designed paint finishing systems, and commercial and consumer gas fired cooking appliances. John, who has more than 22 years’ experience managing outside contractors in site safety requirements and installation of industrial process equipment, is well versed in federal and state worker safety and environmental regulations.

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