Glossary of Pump Terms: G
Galvanic series:
Lists of metals with those on the top of the list being attacked by those lower down in the list. The father apart on the list, the faster the attack.
Gasket:
Used between two static surfaces to provide a seal. Made from a variety of deformable materials.
Gland:
The part that holds one half of the mechanical seal and attaches to the stuffing box.
Grease seal:
A spring-loaded elastomer seal commonly used to seal bearings. Sometimes called a “lip seal”. Not a good choice for sealing the bearing casing of a pump. A labyrinth or face seal would be a better choice.
Glossary of Pump Terms: H
Halogen:
Elements that attack carbon. Fluorine, bromine, chlorine, astatine and iodine.
Hard face:
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.
Harmonic vibration:
Vibrating in harmony with something near by. This can be a big problem for bearings in stationary or non-running equipment.
Hastelloy “C”:
A nickel rich, corrosion resistant metal used for mechanical seal springs and metal bellows because it is not sensitive to chloride stress corrosion.
Head:
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.
Horse power:
33,000 foot pounds per minute. Common methods of measuring work.
Hydraulic balance:
A method of reducing mechanical seal face loading by reducing the seal face closing area.
Hydraulic force:
Occurs any time pressure acts on a seal face area. Force times distance divided by time is a measurement of work done.
Hydrocarbon:
A petroleum product consisting of hydrogen and carbon.
Hydrodynamic seal:
Special geometric features on the seal face that provide lift by taking advantage of the rotation of one seal face upon the other.
Hysteresis:
The delay or lag that causes seal faces to open.
Hydrostatic seal:
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.
Glossary of Pump Terms: I
I.D.:
Inside diameter.
I.S.O.:
International standards organization. Sets pump and seal standards for the metric community.
Impeller:
Attaches to the end of the shaft to impart energy to the fluid being pumped. Available in open, semi- open and closed designs.
Impeller eye:
The center of the impeller or the point where fluid enters the impeller.
Impeller shroud:
The plates located on one or both sides of the impeller vanes. Prevents solids from penetrating behind the vanes.
Impeller vane:
Located between the eye and the discharge side of the impeller. Directs the flow of the liquid to the outside diameter of the impeller.
Inducer:
A small axial flow vane that attaches to the impeller of a centrifugal pump to increase the N.P.S.H. available.
Induction motor:
The most common type used in industry. Has a slippage of 2 to 5 percent compared to synchronous motors.
Inline pump:
Mounted in the piping. No base plate or alignment required.
Internal recirculation:
A loss of efficiency caused by liquid flowing through wear rings or the impeller to volute clearances.