The images are far too graphic to print within this article. But if you do an Internet search on hydraulic injection injuries, you will find plenty of photos and stories that are vivid enough to make a lasting impression and, maybe more importantly, encourage you to give hydraulic systems the respect they deserve.
"Everyone needs to be aware of hydraulic system safety," says Gary Kleiner, training and development manager, Fluid Connectors Group, Parker Hannifin Corp. "It's not only the maintenance technician's responsibility, but everyone who works on and around hydraulic systems under pressure."
Of course, a lot of working with hydraulics is common sense, says Rod Erickson, senior technical instructor, Eaton Training Center. Yet, mistakes happen.
"Mistakes can happen when someone forgets to secure a load or when they forget to bleed the pressure," he says. "People can get lax when they've worked around equipment for a long time. Plus, when you're working on a repair, especially in the field, you're always under the gun. You want the machine fixed right, but you want it fixed now. Time is money and labor is expensive. As a result, you may be in a hurry and that's generally when accidents happen."
A loaded gun
When properly maintained, a hydraulic system isn't necessarily dangerous. But hydraulic hoses and assemblies do have a shelf life; when improperly stored, installed and/or serviced, they can burst and spew hot, highly pressurized fluid that can injure workers or equipment operators standing nearby.
"There is demand to increase the power density of new components," says Erickson. "With weight and space constraints, the only way we can get more power out of a hydraulic system is to increase pressure. We're going to higher and higher pressures all the time. In mobile equipment, 3,000 to 4,500 psi in continuous spaces is not unusual. And there are cases where it can get to 6,000 psi."
"With typical hydraulic systems, pressures can be 5,000 or 6,000 psi, or even higher," agrees Dennis Kemper, team leader, Global Product Application, Gates Corp.
That's a bit intense when you consider it takes just 100 psi to break skin. "A pinhole leak in a hydraulic hose that is under pressure can release hydraulic fluid at more than 600 ft. per second - close to the muzzle velocity of a gun," Kemper points out. "The very fine jet of hydraulic fluid at high pressure will act like a hypodermic needle that may penetrate both protective clothing and skin."
Such hydraulic injection injuries aren't necessarily common, but they can be life changing or. Given the potential severity of such injuries, never touch a pressurized hydraulic hose assembly with any part of your body. If you suspect a leak, use a piece of cardboard, wood or sheet metal to locate it.
Also wear safety glasses and protective gloves, along with any other personal protective equipment appropriate for the application involved. But don't expect them to prevent injection injuries. "It's instinctive to use your hand to feel for fluid leaks," says Erickson. "But keep your hands away from any suspected leaks."
If you suspect an injection injury has occurred, seek medical attention immediately. Injections may initially feel like a bee sting or wire prick, which then turns red and swells.
"Never discount an injury or brush it off as minor," says Kleiner. "Rarely does the initial pain indicate the actual severity of the injury. What looks like a simple puncture wound is, in fact, life threatening. Hydraulic fluids contain a wide range of chemical compounds that are highly toxic within the bloodstream."
Beware of hot stuff
It's important to have an arsenal of reliable diagnostic equipment for servicing hydraulic systems, including a pressure gauge (capable of handling pressures higher than the system pressure) and the hydraulic system schematic. This graphic can be found in the operator's manual or most manufacturers post it online.