Hydraulic Gear Pump
Friday /
Monday / التسميات: Hydraulic Pumps
General Components of Centrifugal Pumps
A centrifugal pump has two main components:
a . A rotating component comprised of an impeller and a shaft.
b. A stationary component comprised of a casing, casing cover, and bearings.
Stationary Components
Casing :
Casings are generally of two types: volute and circular. The impellers are fitted inside the casings.
1.Volute casings are a curved funnel increasing in area to the discharge port. As the area of the cross-section increases, the volute reduces the speed of the liquid and increases the pressure of the liquid.( Volute casings are building a higher head ).
2.Circular casing have stationary diffusion vanes surrounding the impeller periphery that convert velocity energy to pressure energy. Conventionally, the diffusers are applied to multi-stage pumps.( circular casings are used for low head and high capacity )
Suction and Discharge Nozzle
The suction and discharge nozzles are part of the casings itself. They commonly have the following configurations.
1. End suction/Top discharge The suction nozzle is located at the end of, and concentric to, the shaft while the discharge nozzle is located at the top of the case perpendicular to the shaft. This pump is always of an overhung type.
2. Top suction Top discharge nozzle The suction and discharge
nozzles are located at the top of the case perpendicular to the shaft. This pump can either be an overhung type or between-bearing type
2. Side suction / Side discharge nozzles The suction and discharge nozzles are located at the sides of the case perpendicular to the shaft. This pump can have either an axially or radially split case type.
Now ;that’s the most important stationary components.
There’s also (Seal Chamber , Gland , Throat Bushing , Internal circulating device , Mechanical Seal ).
1. Impeller The impeller is the main rotating part that provides the centrifugal acceleration to the fluid. They are often classified in many ways.
a- Based on major direction of flow in reference to the axis of rotation:
Axial flow
Mixed flow
b- Based on suction type
Single-suction: Liquid inlet on one side.
Double-suction: Liquid inlet to the impeller symmetrically
from both sides.
c- Based on mechanical construction
Closed: Shrouds or sidewall enclosing the vanes.
Open: No shrouds or wall to enclose the vanes.
Semi-open or vortex type.
2. Shaft
The basic purpose of a centrifugal pump shaft is to transmit the torques
encountered when starting and during operation while supporting the impeller and other rotating parts. It must do this job with a deflection less than the minimum clearance between the rotating and stationary parts.
There’s also (Shaft Sleeve , Coupling ).
But ;that’s the most important stationary components.
Thursday / التسميات: Hydraulic Pumps
Centrifugal Pump
Working Mechanism of a Centrifugal Pump
A centrifugal pump is one of the simplest pieces of equipment in any process plant. Its purpose is to convert energy of a prime mover (a electric motor or turbine) first into velocity or kinetic energy and then into pressure energy of a fluid that is being pumped. The energy changes occur by virtue of two main parts of the pump, the impeller and the volute or diffuser. The impeller is the rotating part that converts driver energy into the kinetic energy. The volute or diffuser is the stationary part that converts the kinetic energy into pressure energy.
The key idea is that the energy created by the centrifugal force is kinetic energy.The amount of energy given to the liquid is proportional to the velocity at the edge or vane tip of the impeller. The faster the impeller revolves or the bigger the impeller is,then the higher will be the velocity of the liquid at the vane tip and the greater the energy imparted to the liquid.
Sunday / التسميات: Hydraulic Pumps
Hydraulic pumps convert the mechanical energy transmitted by its prime mover (electronic motor, internal combustion engine) into hydraulic working energy.
The type of pump used in an industrial hydraulic system is a positive displacement pump, there are many types of positive displacement pumps.
For this reason, we must be selective and concentrate on the most popular.These are vane, gear, and piston pumps.
So, now we need to know types of pump?
PUMP TYPES
Non positive displacement pumps:
Centrifugal pumps are used to pump large volumes of fluids at relatively low pressures. Like other non positive displacement pumps, they share the common advantages of low noise level, and the ability to pump nearly all fluids without damage to internal parts. Propeller pumps are also non positive displacement pumps.
Positive displacement pumps:
Positive displacement pumps transfer a constant amount of fluid for each cycle of operation. If this internal pump volume can not be adjusted, the pump is considered to have a fixed displacement. If the internal volume of the pump is adjustable, the pump is considered to be variable volume displacement pump. While the drive speed also can be used to change the volume flow rate for a positive displacement pump, this is a less desirable altrnative than varying the internal displacement to change pump output.
Positive displacement pumps are essentially four basic types:
1-Gear pumps (fixed displacement only by geometrical necessity):
· External gear pumps.
· Internal gear pumps.
· Lobe pumps.
· Gerotor.
2-Screw pumps (fixed displacement only).
3-Vane pumps:
· Unbalanced vane pumps (fixed or variable displacement).
· Balanced vane pumps (fixed displacement only).
4-Piston pumps (fixed or variable displacement):
· Axial flow.
· Radial flow.