PUMPS
1. The amount of fluid that must be pumped.
2. The properties of the fluid.
3. The increase in pressure of the fluid due to the work input of the pumps.
4. Type of flow distribution.
5. Type of power supply.
6. Cost and mechanical efficiency of the pump.
Factors Affecting Pump Selection
CENTRIFUGAL PUMPS
Definition:
A pump which uses centrifugal force to develop velocity in the liquid to be handled. The velocity is then converted to pressure as kinetic energy is decreased.
Centrifugal pumps main components:
Centrifugal pumps basically consist of:
1. Stationary pump casing
2. Impeller mounted on a rotating shaft 3. Suction line
4. Discharge line
Pump casing may be (one fabricated piece) or split casing (two or more parts together)
Volute Centrifugal Pump Classification of Centrifugal Pumps
1. According to the pump casing
Diffuser Centrifugal Pump
Diffuser Centrifugal Pump
2. According to the impeller type
Open impeller Semi open impeller Enclosed
impeller
To aid in understanding the pump details and to see the semi closed impeller
Single Suction and Double Suction Impellers
3. Classification by Flow
Centrifugal pumps can be classified based on the manner in which fluid flows through the pump. The manner in which fluid flows through the pump is determined by the design of the pump casing and the impeller. The three types of flow through a centrifugal pump are:
A. Radial flow,
B. Axial flow,
C. Mixed flow.
Multi-stage Centrifugal Pumps
Multi-stage Centrifugal Pumps
Centrifugal Pump Components
Centrifugal pumps vary in design and construction from simple pumps with relatively few parts to extremely complicated pumps with hundreds of individual parts. Some of the most common components found in centrifugal pumps are:
1. wearing rings,
2. stuffing boxes,
3. packing, and
4. lantern rings.
Stuffing box and packing
The packing material may be: Asbestos, Nylon, Teflon, Lead, Copper or Aluminum
Simple View for Lantern Ring and Stuffing Box
Mechanical Seal s
What are mechanical seals
Components of mechanical seals
Types of mechanical seals
Advantages and disadvantages of mechanical seals
Mechanical Seals
Used when packing material is not adequate for sealing the shaft.
Mechanical seals consist of two basic parts (faces), a rotating element attached to the pump shaft and a stationary element attached to the pump casing.
One of these element is called the sealing ring and is held in position by a spring. The other sealing element which is in contact with the sealing ring is called the mating ring.
Each of these elements has a highly polished sealing surface.
The polished faces of the rotating and stationary elements come into contact with each other to form a seal that prevents leakage along the shaft.
Types of Mechanical Seals
A. The rotating mechanical seal
The sealing ring and the spring are rotating with the shaft and the mating ring is held stationary in the pump casing.
The rotating mechanical seal
B. Stationary Mechanical Seals
The sealing ring is held stationary within the pump housing.
The mating ring is fastened rigidly to the shaft. As the pump shaft turns so does the mating ring.
The stationary sealing ring bears against the rotating mating ring and leakage between the two faces is prevented.
