Is your end-user experiencing a fluid leak? It might be a failing seal.
Seals are important to hydraulic components such as pumps and cylinders —they prevent fluid from leaking between parts. Hydraulic seals don’t last forever. Like all hydraulic parts, they will eventually fail and need replacement.
You can reduce damage to hydraulic seals if you keep in mind what typically causes failures and try to prevent damage. However, if you are facing a hydraulic seal failure, identifying the cause of the failure is the first step toward fixing the problem. Six top causes of hydraulic seal failure are:
Cause #1: High Temperatures Harden Seals
Hydraulic seals must be malleable to prevent leaks and contamination. Repeat exposure to high temperatures will harden the seal material. High temperatures are unavoidable. High fluid operating temperatures or high-speed heat generation from stroking operations can create a hazard as seal material becomes brittle. When seals harden, they crack and lose elasticity, leading to seal failure.
Cause #2: Dryness & Stress Cause Wear & Tear
Not enough lubrication or too high a load can wear on the face of a seal lip and cause serious damage.
Cause #3: Bad Installations Leave Scars & Dents
Improper installation can cause cuts or dents in the lip of the seal, which reduces hydraulic seal efficiency and allows foreign elements into the hydraulic fluid.
Cause #4: Pressure & Poor Materials Fracture Seals
When a seal comes under high backpressure, high-pressure spikes or is made of low-grade materials, the seal can fracture from burns, long cracks or parts of the seal breaking off.
Cause #5: Dirt Weakens Seals, Enters Hydraulic Systems
Dirt, mud, powder, small metal or stone chips and other tiny elements attach themselves to hydraulic parts, create dirty hydraulic seals and stop them from keeping contaminants out of the system.
Cause #6: Fluid/Seal Incompatibility
Due to the chemical composition of the material seals are made of, seals are only compatible with certain types of fluids. If the seals encounter fluids they are not compatible with, the seals will break down, swell, or lose their elasticity. Checking the fluid against the composition of the sealing materials using a fluid compatibility chart is the best way to prevent fluid/seal compatibility issues. Make sure any make-up fluid added to the hydraulic system is the same as the fluid already in the hydraulic system.
Seals protect hydraulic systems from heat, chemicals, stress and dirt that cause damage. Knowing the most common causes of seal damage and creating a prevention plan that includes inspections and preventive measures can help you avoid problems from seal failure.
Steve Downey is an Adjunct Fluid Power Instructor at Henry Ford Community College and Macomb Community College. He has worked in the Fluid Power Industry for 30 years in both Industrial and Mobile Hydraulics. Steve Holds 11 International Fluid Power Society certifications.