United States Coast Guard Headquarters
Inspections and Compliance Directorate
June 20, 2017
Safety Alert 07-17
CO2 Hazards are Nothing New
But we’d like to remind you of what not to do!
During two recent vessel inspections Coast Guard Marine Inspectors
participated in and witnessed occasions where the testing and maintenance of
a CO2 system resulted in serious safety threats that could have easily led
to loss of lives. The incidents included an accidental release in the space
where a sensor was being tested that nearly resulted in a fatality and
another situation where CO2 came close to being released without warning
into an occupied engine room space after errors were made during routine
system maintenance. CO2 fire extinguishing systems present an inherent risk
to the personnel involved with their inspection, testing, and maintenance.
Over the years the Coast Guard has become aware of multiple events where
these systems have inadvertently released or leaked and caused the deaths of
shipboard personnel, technicians and inspection personnel. CO2 system
inspection, testing, and maintenance require thoughtful planning and risk
mitigation efforts to prevent such events from happening.
In the first instance, the vessel’s Chief Mate and a Coast Guard Inspector
were testing the fire detection system. The Mate and Inspector went to the
vessel’s hydraulic equipment room and the Mate stood on a spare parts box in
order to apply a heat gun to the heat actuator. The CO2 subsequently
discharged directly above their heads and filled the room. The mate was
overcome by the CO2 release and had to be revived by CPR after being pulled
out of the space unconscious.
The problem was that the Mate directed the heat to a “heat actuator” and
not a “heat temperature transmitter.” The difference between these
components is substantial. The detector is connected by wires to the
monitoring system on the bridge while the release actuator directly connects
to its local CO2 system through tubing. The heat actuator when heated
creates a slight pressure in the tubing immediately activating the pneumatic
control head of the CO2 bottle, releasing CO2 into the space without delay
Crewmembers were unfamiliar with the vessel’s system and had not referred to
the associated manuals. Thus, their testing of the system was conducted
without an understanding of the impacts of their actions, placing them and
the Coast Guard inspectors at risk.
In a second unrelated event, an inspection for certification involving four
Inspectors was taking place while technicians were working on the CO2
system. A Coast Guard Inspector in the machinery space was told that CO2
technicians were going to release the CO2 which was not part of the planned
inspection. He was informed that the system became accidently primed for
release when the pilot system was activated by a technician in training. As
the technician was reconnecting the cable actuated release levers attached
to the tops of the bottles, the activation cables remained connected to the
levers. When the bottles were moved later in the servicing process, the
cable tension increased to the point where the levers were lifted resulting
in the release of charged bottles against a closed valve which prevented
immediate release into the space.
The technicians ultimately decided they needed to release the entire engine
room CO2 system to remedy the situation. They communicated their intentions
to the vessel’s engineers, who performed an accountability of all personnel
in the space. However, their count was incorrect as they missed a Coast
Guard Inspector who was still in the engine room. Only after the
Inspector’s partner realized his associate was missing was another more
thorough sweep of the engine room made and the missing inspector found.
Even after clearing the engine room the situation remained hazardous as
various personnel stood by in the engine control room while the gas was
released. After realizing the magnitude of the CO2 being released, the
personnel in the control room evacuated to the vessel’s main deck and no
further entry was made into the engine room until the fire department ruled
it safe for human occupancy.
As a result of inadequate accountability measures and hazard communications,
the safety of crew members and a Coast Guard inspector was placed at risk.
The Coast Guard notes that both of these instances reflect a lack of
knowledge and risk awareness by the persons involved. The Coast Guard
strongly recommends that:
Only persons adequately trained and properly evaluated be permitted.
to participate in CO2 testing and maintenance procedures onboard vessels;
Every person involved must know and consider the resulting outcomes.
for each step of the testing procedure prior to it taking place; and
Risks associated with CO2 and other systems should never be.
underestimated. Risk prevention activities should always lean towards
providing the greatest safety margins for those involved including 100%
accountability of all personnel aboard the vessel prior to conducting an
operational test of a system.
Coast Guard Navigation and Vessel Inspection Circular (NVIC) 09-00, Change
1, “CARBON DIOXIDE FIRE EXTINGUISHING SYSTEM SAFETY”, contains additional
CO2 safety and inspection information.
This safety alert is provided for informational purposes only and does not
relieve any domestic or international safety, operational, or material
requirements. Developed by the Investigations Division of Marine Safety
Unit Portland, Coast Guard District 13 Prevention Division and the Office of
Investigations and Casualty Analysis. Questions may be sent to
Note: The Coast Guard has previously released CO2 related safety alerts.
Safety Alert 15-14 recommends conducting a comprehensive pre-test meeting
and simulated step-by-step “walk-through” between involved parties prior to
actual testing of complex or potentially confusing systems. Operational
controls for those involved should be implemented to maximize safety and
reduce risk. Additionally, the Coast Guard strongly reminds all maritime
operators of the importance in performing regular vessel specific emergency
drills and to ensure that all crewmembers have the proper knowledge, skills,
and abilities to respond to any potential emergency.