1. DEPARTMENT OF MECHANICAL ENGINEERING
TAE-II (TECHNICAL PRESENTATION)
Name of Subject:- Fluid Power- II
Name of the Topic:- Screw Pumps, different designs
Name of Student:- Digvijay T. Singh
Roll No.:- 53
Semester:- 4th
Section:-D
Name of Faculty:-
Mr. Yogesh Nandanwar
Session: 2015-16
2. Introduction :
Screw pumps are classified as positive, constant-
displacement rotary pumps. The one screw pump is called as progressive
cavity pump. By far, the largest applications of screw pumps are of the
three-screw kind. This pump consist esentially of three intermeshing helical
thread screws housed inside a chamber with an inlet and outlet .
3. Types of Screw Pumps :
1. One screw pump
2. Two screw pump
3. Three screw pump
Exploded View of a Screw Pump :
4. Working of Screw Pump :
The pumping liquid from the inlet is trapped
between the teeth of the idler screws. Though continuous, the flow can be
considered as a series of packets lying between a set of two adjacent threads of
the idler. The rotation of the driver causes each packet of trapped liquid to move
progressively forward in the axial direction and ultimately to the outlet. For each
turn of the driver, the displacement is a constant quantity.
Continuous rotation causes a continuous stream of liquid to be pushed out
of the exit as a constant stream of liquid. The flow rate is a function of the speed
of rotation and also depends as the cube of the diameter of the power rotor. The
speed is relatively low.
6. Advantages of screw pump :
1. It has a good efficiency of about 80-85% which depend upon the
viscosity of the liquid and the pressure head of the pump.
2. It has a flow range of 10 to 1500 litres/minute.
3. It has a speed of 750 to 3500 rpm.
4. It has high suction capability. It run very quietly and reliable and robust.
5. The pump is self-priming.
7. Applications :
Screw pumps find considerable applications in machinery lubrication, fuel-oil
transport.
powering of hydraulic machinery, conveyance of high temperature and viscous
fluid like asphalt and residual oils in refinery.
They find extensive use in ships, commercial vessels and barges to handle
lubricating oils and hydraulic fluids.
