Classification by geometry

• This is a common form of classification of turbo machines and centrifugal pumps in particular, based on the shape of the casing.

Classification by inlet geometry

• This is commonly applied in turbo machines and to a lesser extent rotary pumps. It describes the basic geometry of the suction entry to the pump.

Classification by layout

• This refers to the design (or possible) position of the pump shaft access, for example, horizontal, vertical, or inclined. This indicates the mounting requirements (and likely floor space required) in the case of turbo machines. A further classification which applies with turbo machines, particularly is how the casing halves divide for disassembly where applicable.

Classification by mounting

• This is generally descriptive of the design method of mounting the pump and is applicable but not necessarily always specified for all types of pumps.

• Classification by operation

  • This basically describes the design duty of the pump, for example, main pump, source pump, standby pump, auxiliary pump, etc. It does not necessarily follow that the use of such a pump is restricted to the specified operation.

  Classification by liquid handled

  • This is a specific classification indicating that the pump is able to handle a particular type or types of fluid or product.

  Classification by material

  • This describes the materials from which the pump or the wetted part are constructed and thus its likely suitability for handling chemically active or corrosive fluids for example.

  Classification by drive

  • This specifies the method of drive intend for the pump, for example, electric motor, integral (electric) motor, magnet drive, manually driven, turbo driven, shaft driven etc.

  Submersible pumps

  • Pumps of this type are of sufficient importance to warrant a classification of their own, representing the type of pump with integral electric motor which can be immersed in the product being handled. They can be subdivided into various categories according to intended duty, for example deep well, borehole etc. and by the form of canned motor.

  • Name Classification or type	Description		Remarks
    Turbo machines Roto-dynamic)	1.   Centrifugal 2.   Mixed flow   3.   Axial flow 4.   Channel	(a)        Helical (b)        Diagonal	General classification
    		(a)        Side channel (b)        Peripheral
    Single-stage	Head developed in a single stage
    Two-stage	Two impellers in series		Usually descriptive of centrifugal pumps only
    Multi-stage	Several impellers in series
    Low pressure	Single stage pump with low discharge pressure		Nominal classification by discharge pressure developed.
    High-pressure	Pump with high discharge pressure
    Super-pressure	Pump with very high discharge pressure
    Single-entry	Single suction entry to impeller(s)
    Double entry	Entry may be single (single suction) to a double entry impeller or two single entry impellers in parallel; or split into two suction branches (double suction)		Classification by inlet (suction) geometry; the same classification can apply to other pump types, e.g. rotary pumps
    Axial inlet (end suction)	Axial inlet
    Side inlet (side suction)	Radial or tangential inlet
    Top inlet (top suction)	Horizontal pump with inlet on the top
    Bottom inlet (bottom suction)	Horizontal pump with inlet on the bottom		Classification of turbo machines by basic layout’ the same classification can apply to other pump types.
    Horizontal	Roto-dynamic pump with horizontal shaft
    Vertical inclined	Axial flow pump with inclined shaft

     

  • Name Classification or type	Description	Remarks
    Volute	Centrifugal pump with spiral discharge casing.	Classification based on shape of casing; other descriptions may also apply.
    Double volute	Centrifugal pump with two volute casings at 1800 delivering through a single discharge.
    Diffuser	Centrifugal pump with fixed diffuser vanes following the impeller
    Annular (casing)	Centrifugal pump with constant cross section circular discharge casing
    Bowl	Diagonal sub-type mixed flow pump with bowl shaped casing
    Tubular	Axial flow pump with straight tube casing
    Angle	Axial flow pump with curved tube casing.
    Barrel	Multi-stage centrifugal pump with stages assembled in a shaped outer casing.
    Overhung	Centrifugal pump with impeller mounted outside the bearings.
    Split casing	1.   Axially split (horizontally split) – casing divides in the plane of the shaft (thus horizontally split in the case of a horizontal pump). 2.   Radially split (vertically split) – casing divides in a plane at right angles to the shaft (thus vertically split in case of a horizontal pump). 3.   Diagonally split – casing divided in a plane diagonal to the shaft.	Classification by division of casing halves (where applicable)

    Name Classification or type	Description	Remarks
    Foot mounted	Mounting feet incorporated pump body	Descriptive of method of mounting the pump; the same classifications can apply to other types of pumps
    Frame mounted	Vertical pump (usually) mounted on frame to transfer weight of top mounted motor to foundations.
    Lantern mounted	Lantern form mounting fitted to, or integral with the pump casing the lantern may be in the form of a skit (skit mounted)
    Pedestal mounted	Horizontal pump with casing mounted on a pedestal or head stock.
    Flange mounted	Overhung pump flange-mounted to driver
    Wall mounted (bulkhead mounted)	Casing designed for mounting on a wall or bulkhead.
    Tank mounted	Pump designed for suspended mounting on a tank flange.
    Pipeline mounted (in line pump)	Pump which is designed to mounted directly and unsupported, in a pipeline.
    Direct mounted	Pump mounted directly on an extension of its shaft
    Integral	Pump incorporated as a part of an integral machine; also known as a built-in pump.

    Name Classification or type	Description	Remarks
    Wet sump pump	Usually a vertical centrifugal pump of a suitable design to be immersed.
    Dry sump pump	Usually a vertical pump with enclosed suction, or suction inlet installed in a dry chamber.
    Canned motor pump	Glandless pump set or submersible pump with sealed electric motor.
    Wet motor pump	Glandless pump set or submersible pump with stator windings in contact with fluid being pumped.
    Submersible pump	Pump set capable for operation immersed in fluid being pumped.
    Immersible pump	Pump set capable of operation partially immersed in fluid being pumped.

    Basic type	Stage(s)	Layout	Entry	Casing
    Centrifugal	Single-stage Single-stage Multi-stage   Multi-stage (balanced) Single-stage Single-stage Multi-stage	Horizontal Horizontal Horizontal   Horizontal   Vertical Vertical Vertical	Single Double Axial (single or double) Back-to-back   Single Double Single	Volute-split or end pull-out Volute-split or end pull-out Ring type for low to medium heads.  Barrel type for high pressures Volute (usually)   Volute-split casing Volute-split casing Volute
    Mixed flow (helical)	Single-stage Single-stage Single-stage	Horizontal Horizontal Vertical	Single Double Single	Volute-split casing or end pull-out Volute-split casing Volute-split casing
    Mixed flow (diagonal)	Single-stage Single-stage Multi-stage	Horizontal Vertical Usually vertical	Single  Single  Single	Concentric Concentric Concentric
    Axial flow	Single-stage Multi-stage	Horizontal Vertical Usually vertical	Single  Single  Single	Concentric Concentric Concentric

    Construction parameter	Classification	(Alternative descriptions) sub-types or
    Alignment of axis	(i)  Horizontal (ii) Vertical
    Suction entry	(i)  Single (ii) Double	(a) Top suction (top inlet) (b) Side suction (side inlet) (c) Bottom suction (bottom inlet)
    Casing	Split casing	(a) Horizontally split (axial split) (b) Radially split
    Impeller support	(i) Overhung (iii) Between bearings	(a) Internal bearings (b) External bearings
    Mounting	(i)          Integral (ii)         In-line (iii)        Foot mounted (iv)       Frame mounted (v)        Lantern mounted (vi)       Pedestal mounted (vii)      Bung mounted (viii)    Flange mounted (ix)       Tank mounted (x)        Wall mounted (xi)       Skid mounted	(ii) (Pipeline mounted)     (v) (Skit mounted; lantern based) (vi) (Head stock mounted)   (viii) (Flanged overhung pump) (ix) (Suspended pump)   (xi) (Bulk head mounted)
    Rotor disassembly	(i)  Pull-out	(i) Withdrawable rotor assembly
    	(ii) Horizontally split casing
    Seals	(i) Packed glands (ii) Mechanical seals (iii) Glandless

    MULTI-STAGE PUMPS

    Most multi-stage pumps are built with single suction impellers in order to simplify the design of the interstage connections.  Two obvious arrangements are possible for the single suction impellers. Several single suction impellers may be mounted on one shaft, each having its suction inlet facing in the same direction and its stages following one another in ascending order of pressure.  The axial thrust then balanced by a hydraulic balancing device.  An even number of single suction impellers may be used, one half facing in one direction and the other half facing in the opposite direction.  With this arrangement, axial thrust on the first half is compensated by-the thrust in the opposite direction on the other half.  This mounting of single suction impellers back to back is frequently called opposed impellers. 

    An uneven number of suction impellers may be used with this arrangement, provided the correct shaft and inter-stage bushing diameters are used to give the effect of a hydraulic balancing device that will compensate for the hydraulic thrust on one of the stages.  It is important to note that the opposed impeller arrangement completely balances axial thrust only under the following conditions.

  • Impellers can be classified according to the major direction of flow in reference to axis of rotation.  Accordingly, centrifugal pumps may have

  • i)Radial-flow impellers

    ii)Axial flow impellers

    iii)Mixed flow impellers (combining radial and axial flow principles)

    In addition, impellers can be further classified

    i)Single suction with a single inlet on one side

    ii)Double suction with water flowing to the impeller symmetrically from both sides.

    The mechanical construction of impellers gives a still further sub-division into:

    i)Enclosed, with shrouds or side walls enclosing the water ways.

    ii)Open with no shrouds

    iii)Semi open or semi-enclosed.

  • Accordingly, a pump in which the head is developed by a single impeller is known as a single-stage pump and, as previously stated, two or more single-stage pumps can be connected in series or all the impellers can be incorporated in a single casing.  The unit is then called a multi-stage pump. 

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