USCG Marine Safety Alert 03-14
US Coast Guard has issued Marine Safety Alert 03-14 to remind to vessel owners/ operators and also fire safety equipment servicing companies to use caution when replacing components on hand portable fire extinguishers.
While examining the activities surrounding a fire onboard a vessel, Coast Guard investigators from SectorHampton Roads learned of the failure of a hand portable 15 pound (lb) Carbon Dioxide (CO2)extinguisher. During a fire-fighting event, a crewmember attempted to use a 15 lb CO2 extinguisher,but the extinguisher failed to properly discharge and only seeped from the neck of the extinguisher.The fire was extinguished by another crewmember using a dry-chemical fire extinguisher.
The investigators had the extinguisher examined at a fire-fighting equipment service center. Theydetermined that the hose and discharge horn had been replaced at an earlier time. The end of thehose screws on to a diffuser on the side of the discharge valve/handle assembly of the extinguisher.The diffuser is a ported protrusion on the male end of a ninety degree fitting. On the side of theprotrusion are orifices through which the CO2 flows. The examination revealed that the spherical endof the protrusion, which contains no orifices, bottomed out against the orifice in the connection fittingthat leads to the hose and horn assembly. The flow of CO2 was thus completely blocked.
It was further noted that the male threads of the diffuser were tapered US national pipe threads, whilethe female threads of the hose connection were straight. This difference likely allowed the hoseconnection to be tightened further than intended on the diffuser threads, permitting the spherical endof the diffuser to bottom out against the orifice in the tube. This may have also resulted in thereported leakage from the neck of the extinguisher due to back pressure.
Newer types of diffusers exist in which the orifice follows the length of the protrusion and the end isnot spherical. However, the issues regarding the tightening of the two components and theimportance of ensuring proper lengths and compatibility of the threaded and machined surfacesremain. Binding or bottoming out should not occur except at the threaded surfaces. Replacementparts should be as specified by the original manufacturer of the extinguisher.
The Coast Guard does not know the extent of this problem or if this particular instance of failure is anoutlier. It involved an older CO2 extinguisher with a hose and horn assembly that had been replaced.We do not advise owners/operators or vessel personnel to take apart or disassemble theirextinguishers. Only technicians from fire equipment service companies should work on thisequipment.
The Coast Guard only advises that if owners/operators, based on visual examination of theirequipment, believe there is a possibility of potential blockage of flow due to conditions as describedabove, they should contact a qualified fire equipment service company for more thoroughexamination, testing, and repair, if needed.
| The Coast Guard recommends that fire equipment service companies be aware of the potentialproblems described above, and ensure that all replacement components for servicing hand portablefire extinguishers are as specified by the original extinguisher manufacturer. Service companies thatmarket replacement parts should also note the importance of these concerns and advise theircustomers accordingly. If the appropriate replacement parts are not available, the extinguishershould be replaced. |
Source: USCG
