A "booster" pump boosts (increases) the pressure at a midpoint between point 1 and point 2. That is, the pressure of a flow of some liquid is raised to P1 as it passes through pump 1. That pressure is again raised to P2 as it passes through pump 2.
One example of boosting the pressure is raising the NPSHA as mentioned.
I designed a process that required that the fluid (a bottoms product from a distillation column) pass to a separation vessel. From that vessel the bottoms product needed to flow to a storage vessel over one mile away. The first pump did not produce enough head so a booster pump was used for the remaining distance.
A third example is in fire fighting. Many municipalities supply fire water at pressure P1. A higher head may be required to impulse the water to the fire. Fire trucks have a booster pump to raise the water pressure as required.
Its a definition i guess - but IMO a booster is always upstream the main pump (in the 3. example given chemebabak its downstream.
The 2. example given by chemebabak - why is that not just a pump. All pumps "boosts" the pressure - so by that definition all pumps are booster pumps.
With regards to "midpoint": If you have a hig speed water inject pump that discharges at 250 barg and has a NPSHr=8 barg - then a booster pump shall deliver 125 barg (c.f. the definition by chemebabak)? I think not! The booster pump shall deliver at around 10-12 barg so that the main pump can deliver the main of the head.
MortenA,
your definition of a booster pump is a very narrow one that is used to increase the NPSHA of a pumping system.
In a long pipe line application, booster pump stations are often installed where a single pump is not viable in terms of head and also to reduce pipe line pressure rating.
A pump is pump until the user gave it a name based on the function it is require to performed in a process.
e.g
a "pump that pumps out bottoms product from a distillation column is often refer to as "bottom pump" in the data sheet. The pump that feed the crude to the column is known as Charge pump.
