- Elements that attack carbon. Fluorine, bromine, chlorine, astatine and iodine.
- A seal face either rotating or stationary. The most common materials are silicone carbide, ceramic, tungsten carbide, Stellite, Ni-resist. The hard face must be the wider seal face.
- Vibtrating in harmony with something near by. This can be a big problem for bearings in stationary or non running equipment.
- A nickel rich, corrosion resistant metal used for mechanical seal springs and metal bellows because it is not sensitive to chloride stress corrosion.
- The equivalent height of the liquid. 20° C. water is used as the standard where 10 meters (33.9 ft.) of water equals one atmosphere (14.7 psi. or 1 bar). The term head is used instead of pressure in the centrifugal pump business.
Helium Light Band
- A method of measuring seal face flatness. One helium light band equals 0.0000116 inches or 0.3 microns. Seal faces are normally lapped to within three helium light bands of flatness.
- 33,000 foot pounds per minute. A common method of measuring work.
- A method of reducing mechanical seal face loading by reducing the seal face closing area.
- Occurs any time pressure acts on a seal face area. Force times distance divided by time is a measurement of work done.
- A petroleum product consisting of hydrogen and carbon.
- Generated at the seal faces because, for all practical purposes, liquid is not compressible.
- Special geometric features on the seal face that provide lift by taking advantage of the rotation of one seal face upon the other.
- A premature fatigue of metal caused by the presence of free hydrogen. This is a major cause of ceramic breakage in hot water seal applications, and bearing fatigue if moisture penetrates into the bearing case.
- An ion formed by the transfer of a proton from one molecule of water to another. Used to determine the pH of a substance. Each step increases by a factor of ten.
- Maintains a controlled gap between the seal faces by balancing the open and closing forces. There is a small amount of leakage across the faces when the shaft is rotating. Used in some compressor applications, but not very practical for the chemicals found in the process industry.
- The delay or lag that causes seal faces to open.