THE PUMP EVERYTHING

Basic Concepts

Area        x    1/Velocity

Velocity  x     1/Pressure 

Area        x      Pressure

Reducer reduces the Pressure   - Nozzle

Difusser Difusses the Pressure  - Diffuser

In a Nozzle , since flow happens from higher potential to lower potential, Pressure energy is converted into kinetic energy , so pressure decreases Flow from High pressure to low pressure.

When we throttle the flow of water in a pipe it sprays ,,  because area decreases , Velocity increases

Pump

The purpose of a pump is to add energy to a fluid, resulting in an increase in fluid pressure, not necessarily an increase of fluid speed across the pump.

Turbine

The purpose of a turbine is to extract energy from a fluid, resulting in a
decrease of fluid pressure, not necessarily a decrease of fluid speed across
the turbine.

When used with gases, pumps are called fans, blowers, or compressors, depending on the relative values of pressure rise and volume flow rate

	Fan	Blower	Compressor
	Low	Medium	High
Q	High	Medium	Low

Pump Classification

                        

Centrifugal Pump :

Centrifugal Pump works in following steps, 1.      Sucks the fluid by creating a low pressure zone at the eye of the impeller at the expense of kinetic energy of rotating impeller. 2.      Creates Kinetic energy by the Centrifugal action 3.      Converts the Kinetic energy to pressure energy by diffusing passage and throwing off radially across the casing. Pressure Variations – flow accordingly Sump – eye – casing - Dischage Sump – High Pressure Eye          - Low Pressure Casing       – High Pressure Discharge – Low Pressure A pump does not create pressure, it only creates flow. The gauge pressure is a measurement of the resistance to flow. Centrifugal Pumps are "constant head machines" The head is constant, even if the density (and therefore pressure) changes.

TURBO MACHINERY EQUATION H = H – head U2 – Blade tip velocity Β2 – Blade angle R2 – radius B2 – Width of the impeller H > 0 --- pump H < 0 --- Turbine Impeller Blade Types Forward   β2 <900 Cot β2 > 0  Slope+ve Radial      β2 =900 Cot β2 = 0  Slope Co Backward β2 900   Cot β2 < 0  Slope -ve Backward is always Preferred Because Power α HQ  Q↑ H↓

	Performance Curve Q         : Flow rate H avail : Calculated from Turbomachinery eq. BHP     : Energy supplied to the Motor Ƞ          :   = Free Delivery Head is Zero and Flow is Maximum. This is only possible when there is no resistance to flow from inlet and outlet. Pump is free to flow. Shut off head Q=0 Head is maximum. Pump is not doing any work. This condition is developed when the discharge valve is closed and the pressure develops to max but no flow.
	System curve H req  : Calculated from Energy Equation hL depends on Q, Hence H req varies for diff Q Operating Point : When Hreq and H avail meets.
	Cavitation : Formation of Vapour bubble when suction pressure is going below Vapour Pressure/Saturation pressure at saturation Temperature. Due to the decrease in Pressure across the suction, vapour bubbles are formed ,as they exit through the diffusing passage they feel a high pressure and  collapse. Bubbles collapse into small droplets and that is going to impinge on the surface of the Object.
	Net Positive Suction head :  Difference between static pressure at the suction point and Vapour Pressure at same temperature. Minimum Head to avoid Cavitation NPSH avail= (  +   + Z) Suction –hL- NPSH Req = Given by designer of the  pump  To Avoid Cavitation NPSHa > NPSHr

Impeller Types

Impeller design is the most significant factor for determining performance of a centrifugal pump. A properly designed impeller optimizes flow while minimizing turbulence and maximizing efficiency.

The impeller of a centrifugal pump can be of three basic types:

• Open impeller. Open impellers have the vanes free on both sides. Open impellers are structurally weak. They are typically used in small-diameter, inexpensive pumps and pumps handling suspended solids and thick slurries.
• Semi-open impeller. The vanes are free on one side and enclosed on the other. The shroud adds mechanical strength. They also offer higher efficiencies than open impellers. They can be used in medium-diameter pumps and with liquids containing small amounts of suspended solids. Because of minimization of recirculation and other losses, it is very important that a small clearance exists between the impeller vanes and the casing.
• Closed impeller. The vanes are located between the two discs, all in a single casting. They are used in large pumps with high efficiencies and low required Net Positive Suction Head. The centrifugal pumps with closed impeller are the most widely used pumps handling clear liquids and thin liquids. They rely on close-clearance wear rings on the impeller and on the pump casing. The closed impeller is a more complicated and expensive design not only because of the impeller, but the additional wear rings are needed.if used for high viscous fluids it  may clog the impeller.

https://www.youtube.com/watch?v=xXVOdpJ7u8g