ID: Inside diameter.
Impeller: A device that attaches to a rotating shaft and converts the energy of motion, into the fluid being pumped.
Impeller eye: The center of an impeller, also the point at which the liquid enters the impeller.
Impeller eye diameter: The diameter of the opening where the fluid enters the impeller.
Impeller locating ring: A ring concentric with the shaft that prevents the impeller from moving axially. Used to place the impeller on the shaft at the appropriate position
Impeller nut: A fastener, usually threaded and hexagonal that fastens the impeller to the shaft in overhung pumps.
Impeller setting: Open impellers require a clearance between the discharge and the volute/back pump plate. It is necessary to set this clearance only after the pump reaches its normal operating temperature and must be reset to compensate for wear.
Impeller shroud: A set of plates located on either side of the impeller vanes to prevent solids from entering and damaging the impeller.
Impeller vane: A mechanical component of the impeller that directs the flow of liquid from the eye to the discharge, located at the outer diameter of the impeller.
Impeller vane pass frequency: If an impeller is rotating at 3560 rpm and has 5 vanes, then the impeller vane pass frequency can be calculated by multiplying the number of vanes by the rotational speed of the impeller. In the case above, the result is 17,800.
Implode: The opposite of explode. Bubbles implode if moved to a higher-pressure region of the pump. This can be noisy, damaging the pump's metal parts. Also known as cavitation.
Inboard: The relative position of components in a pump. Inboard refers to components that are closer to the pump coupling, while outboard refers to those further away from the pump coupling. Also known as “inboard side” or “inboard end”.
Inclusion: A non-metallic contaminating piece of material that has become enmeshed in the metal during its manufacture.
Incremental balancing: Balancing a rotor in stages, after adding no more than two major components. Incremental balancing results in a more maintainable balancing.
Inducer: A small axial vane that is attached to the impeller to reduce the NPSH.
Induction motor: An induction or asynchronous motor is an AC motor in which current is induced in the rotor by a magnetic field generated by the stator by the process of induction.
Inline pump: A pump mounted in a fluid flow system. No separate mounting or base plate is required.
Inside mounted seal: A mechanical seal in which all components are mounted in the process fluid.
Intergranular corrosion: A type of corrosion in metal where the corrosion between the crystals of the metal are more likely to corrode than the crystals themselves.
Internal gear pump: A pump that uses gears to displace the process fluid. The gear or gears are housed in a casing with low clearance. One edge of the gear faces the inlet as the other faces the outlet. When the gear turns, liquid is trapped in the space between the teeth and is thereby moved from the inlet to the outlet. An internal gear pump differs from an external gear pump, which uses two gears with teeth that both face externally, in that it uses a set of two gears, but one acts as a rotor (large ring gear with teeth facing internally), and the idler, a small gear interior to the rotor.
Internal recirculation: Loss of efficiency due to the small eddies and recirculating currents in a centrifugal pump.
IOS: International Standards Organization. Sets pump and seal standards for the community. Defines the popular ISO 9000 standard for management.
Iteration: Repeating a process and approaching a goal or target. Used to find the asymptote in functions. Very dependent on modern computer algorithms.