Below is a list of Hydraulic Seals manufacturers from Union City, California. Hydraulic seals, which are a variety of mechanical seal, are ring-shaped components designed to prohibit or limit the leakage of fluid from a device in a pneumatic or hydraulic system. Most seals are made of soft, flexible elastomeric materials that exhibit superior air and water tight sealing abilities. They are vital components in moving machinery and without them, fluid power could not be effectively converted into linear motion.