POSITIVE DISPLACEMENT PUMPS:
A positive
displacement pump is one in which a definite volume of liquid is delivered for
each cycle of pump operation.
They are of two types:
1) Rotary: Gear (external-gear, internal-gear),
lobe, screw, sliding vane, Radial piston pump.
2) Reciprocating:
(a) Plunger
Type (b) Piston Type (c) Diaphragm type
ROTARY
PUMPS:
— 1. Usually
rotary pumps consist of a fixed casing containing gears, vanes, pistons,
screws, or similar elements operating with minimum clearance.
2. — Instead
of throwing a liquid as in a centrifugal pump, the rotary pump traps it,
pushing it around the closed casing, much like a reciprocating pump.
—3. Common
types of rotary pumps used today include gear(external-gear, internal-gear),
lobe, screw, sliding-vane, Radial piston pump.
RADIAL PISTON PUMP:
