On container handlers, hydraulics drive the motion of the boom or arm and can also drive the wheels. Hydraulic oil spraying or leaking from this system and landing on hot components in the engine and hydraulic compartment causes 90% of fires in container handling equipment. Regular hydraulic system maintenance and inspection, procuring quality hydraulic hoses and components, and installing fire suppression systems can significantly reduce productivity and injury risks associated with fire caused by hydraulic system failure. Keep reading to learn more about how the fire starts and how to prevent it.
What are Hydraulics in Container Handling Equipment?
A hydraulic pump pressurizes hydraulic oil in a hydraulic system, which is contained in a series of hoses. Valves control the flow of this oil through the hoses. When certain valves are closed, pressurized hydraulic oil is sent in a particular direction through the hose system to physically push forks or levers or spin a rotary motor. This is the mechanism that drives the motion of booms and arms on container handlers and can also drive the wheels.
At What Temperature Does Hydraulic Oil Ignite and Why is This a Problem?
Hydraulic oil flashpoints range from 300-600 degrees Fahrenheit (150-315 degrees Celsius). Engine compartments on container handling equipment are closed compartments that can trap heat and reach temperatures of 450 degrees Fahrenheit (230 degrees Celsius) or higher. When operating properly, hydraulic oil is insulated in hoses and kept away from hot engine components; however, failure to contain the hydraulic oil in the hoses can lead to a fire.
How Can the Hydraulic System Cause a Fire?
The majority of hydraulic system fires are caused by hydraulic hoses rupturing and spraying hydraulic oil onto hot engine components. Poor manufacturer quality, manufacturing defects, wear, weather, and pushing a hose past its rated lifetime can all lead to a hydraulic hose rupture. Since this oil is under high pressure (+1000 psi), oil will spray out of the ruptured section in the hose. More dangerously, the hydraulic oil will continue to spray until the engine is shut down or the fluid has run out, feeding the fire.
"It's almost like spraying it out of a nozzle or creating a mist. That creates a lot of surface area of the fluid that can easily ignite at temperatures even lower than the flashpoint. In an engine bay with lots of hot components like the turbo, there's a high likelihood the oil will ignite, creating a big fireball. There are some pretty dramatic videos of it out there.” -Brian Cashion, Engineering Manager, Firetrace
Another common cause of a hydraulic system fire is from hoses and valves leaking and dripping hydraulic oil onto hot engine components. This can be related to improper maintenance. Loose connections, abrasion, and manufacturing defects can cause leaks. If the leaked oil lands on a hot engine component, this could also cause a fire. Although, a leak is less likely to cause a fire than a ruptured hose.
How Can the Risk of Fire Damage be Minimized?
Maintenance can help reduce the chance of fire but not completely prevent it. Maintenance schedules can be impacted by frequent use of equipment, not allowing for proper maintenance as the equipment is needed to maintain productivity. These schedules can also be impacted by financial pressures to reduce planned maintenance to increase productivity. Lastly, unanticipated wear and damage from the punishing environment of container yards can accelerate the need for maintenance.
“Though sourcing high quality components, regular inspections, and on-time component replacement can minimize the chances of a fire from hydraulic system failure, it is difficult to anticipate when a hydraulic hose will rupture. They are rated to a certain amount of hydraulic pressure cycles, which doesn’t always directly correlate to equipment operating time, which is what terminal maintenance teams use to determine when equipment is ready for service.” -Brian Cashion, Engineering Manager, Firetrace
Installing a Firetrace automatic fire detection and suppression system in the engines of container handling equipment, like reach stackers and RTG cranes, can mitigate the risk and damage of fire from hydraulic leaks. In addition, Firetrace systems can power automatic shutdowns of the engine and hydraulic system upon a fire, preventing reflash and continuous feeding of the fire.