Impeller - a the part of the rotating element of the pump which imparts the force to
the liquid pumped. The impeller has vanes which vary in number and discharge
angle to give the desired performance.
Impeller eye area - the net opening of the impeller, usually the area of the impeller
suction less the area of the vane blockage.
Impeller eye diameter - the diameter of the impeller suction opening where the
liquid enters the impeller.
Impeller locating ring - a circular piece used to locate the impeller on the shaft
and prevent it from axial movement.
Impeller nut - a threaded piece, usually hexagonal in shape, used to fasten the
impeller on the shaft of an overhang pump.
Impeller shroud - part of impeller casting which is a circular disk that encloses
the impeller vanes; front shroud refers to one on the suction side, back shroud
refers to one on the opposite side.
Impeller vane pass frequency - a frequency, or cycle, corresponding to the
number of vanes in an impeller multiplied by its rotational speed. Example, a
five-vane impeller rotating at 3560 RPM has a vane pass frequency of 5 x 3560 =
17,800 cycles per minute. Also known as blade pass frequency.
Inboard - the state of being closer to the pump coupling as opposed to the
outboard which is on the opposite side. Thus, an inboard impeller, inboard cover,
or inboard bearing housing, is closer to the coupling whereas an outboard
impeller, outboard cover, or outboard bearing housing, is on the opposite side or
is farther away from the coupling. (Same term as inboard side, or inboard end).
Incremental balancing - rotor balancing after the addition of no more than two
major components, such as impellers, with balance corrections applied;
incremental balancing results in a more sustainable rotor balancing.
Inside mounted seal - a mechanical seal with its seal head mounted inside the
seal chamber cavity that holds the liquid to be sealed.
F: glossary I1