The use of an after-market coupler and human error were blamed for the rupture of a spreader that blasted hydraulic fluid into a firefighter’s face during routine training last year.
The incident was brought to light through the National Firefighter Near-Miss Reporting System, where the identities of people filing reports are confidential with the objective of improving safety. Near-miss officials followed up by asking the tool manufacturer, TNT Rescue Systems, to investigate and respond.
The firefighter involved was wearing full personal protective equipment with the shield down on his helmet, according to the near-miss report (08-533), which was filed by an assistant chief. The force of the hydraulic fluid knocked the firefighter’s helmet off and hit him in the eyes and cheek, the report said. He received emergency care with follow-up appointments with a doctor and an eye doctor, and no lasting effects were reported.
“We removed our extrication spreader from our rescue truck and placed the tool on the ground,” the report begins. “Our gas-powered power unit was started and left at idle. Our mission was to open and close the tool to check the operation… When the tool opened to approximately four inches, the spreader ruptured the length of the housing.”
The report said the tool, which had been run the night before in the same manner, over-pressurized due to an incorrect connection on the return hose couplings. The report also said the relief valve had opened, but could not keep up to the pressure, causing the rupture.
“Had this been an actual incident,” the report said, “the pump would have been at full throttle and would have been much worse.”
Tim Blanton, a TNT engineer, provided near-miss officials with the results of the company’s investigation of the incident, which involved an S-100-28 spreader that the department had owned since 1998.
“The male coupler on the tool was a non-bleeder coupler,” he wrote. “All TNT tools and extension hoses are factory equipped with male bleeder couplers.”
He said TNT Rescue Systems incorporates two safety features, a relief valve built into the tool rotor under the twist valve handle and the male bleeder coupler.
“Both items are in place on the return circuit of the system to prevent over pressurization of the tool,” Blanton wrote. “The relief valve had opened in the handle… The external change of the coupler exceeded the capacity of the relief valve.”
Blanton concluded that the cylinder failure was caused by an over-pressurization of the return side of the tool, which “likely occurred as a result of an incomplete connection and lack of a bleeder coupler in the return circuit.”
Twice The Pressure
“As the spreader arms ceased movement, with no release of the control valve, the system was able to build in excess of twice the operating pressure on the return side, causing the cylinder to split,” he wrote.
In an equipment report stemming from the incident, near-miss officials said the after-market coupler was installed as part of a tool-mounting project by a local refurbishing company hired by the fire department. “The mismatched coupler was also not connected correctly, which prevented the tool from relieving pressure properly,” they said.
Regarding the finding of operator error, near-miss officials noted the tool was stopped after it was partially opened.
“Given there was no load on the tool, the operator should have recognized this was not a normal occurrence and released the operating handle,” they wrote. “The operator continued to rotate the operating valve, putting pressure on the system until the cylinder collar exceeded burst strength (in this case 30,000 psi).”
Wear Eye Protection
TNT recommends that fire departments consult manufacturers before substituting after-market parts. The company also said hydraulic rescue tool users should wear eye protection, as well as a face shield, when operating the equipment.
Near-miss reports contain a section called “lessons learned,” and the assistant chief who filed the report said one of those lessons was to wear “goggles” when operating high-pressure tools.
“A second lesson, which we felt we had in place, is to have a repair/maintenance plan that covers the entire tool with your dealer,” he wrote. “We now know of more ‘areas’ that need to be serviced.”
And he mentioned a third lesson – to check couplings “each and every time” before using the tools. “Checking them after you remove from storage,” he said, “will verify that the couplings are not knocked loose when preparing to use the tools.”