Pressure: It is critical to know both the system working pressure and the pressure of any surges or spikes in the system. The published maximum working pressure of the hose must be greater than the pressure the system can surge to. This information is provided on the hose layline.
Safety solutions — Planning and prevention
Hydraulic fluid injection injuries can result in tissue damage, amputation, and death. Advance planning for prevention and treatment is critical. Should an injury occur, there is no time for prep — it has already passed.
Fluids in high-pressure applications can escape from pinhole leaks in hoses caused by a number of factors including: age, incompatible fluids, hose twist, and minimum bend radius violations. These pressurized fluids travel at bullet speed and can penetrate deep under the skin. Yet, the injured person may feel only a slight pricking sensation. Rarely does the initial pain indicate injury severity. What looks like a simple puncture wound is life threatening. Hydraulic fluids contain a wide range of chemical compounds that are highly toxic within the bloodstream.
Immediate treatment required. Hydraulic fluid can quickly destroy tissue, leading to gangrene and amputation (as occurs in nearly half of all instances). Rushing the injured person to the nearest hospital may not be adequate. Medical professionals classify an injection injury as a surgical emergency. But because the wound looks harmless, the treatment protocol often given is “Low” instead of “Critical” priority.
Note that many doctors are not experienced in treating injection injuries. Plan ahead for proper treatment by locating a practiced caregiver (a hand surgeon is best). Then, issue wallet cards with the name, address, and phone number of the medical facility and/or surgeon. On the card’s back, list the type, amount, and pressure of the fluid injected as well as the exact time, body location, and penetration angle of the injury.
To ensure safety, employees should never come close to fluid power hoses and fittings when the system is pressurized. The most common cause of injection injury is using hands or fingers to detect leaks. Thick leather gloves offer little protection — pinhole-size leak can propel fluid at 600+ feet-per-second. To perform a visual inspection, shut down the system. If a system must remain pressurized, or when hoses are routed in hard-to-see locations, use a pole with a piece of cardboard attached to check for leaks.
Eric McCarthy is product manager for Parker Hannifin Corporation, Hose Products Div. He gave a presentation on this topic at the Cygnus Aviation Expo in Las Vegas.
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