What is a Vacuum Pump
Vacuum pumps move air, powders, fluids etc, by creating a vacuum.
When air is removed from a sealed space, it creates a pressure deficit which allows the product to flow into that space. In other words, the product moves from a place of higher pressure to a place of lower pressure.
The first vacuum pump was created in approximately 1650, but it is likely that suction pumps have been in existence for thousands of years, because a bamboo reed used as a straw would qualify as a primitive, man-powered suction pump.
Vacuum pumps are usually classified in one of three basic categories: positive displacement, entrapment or momentum transfer, also known as molecular.
Positive displacement pumps (PD Pumps) have the following sub classes:
Rotary vane pump, the most common; Diaphragm pump, zero oil contamination; Liquid ring which offer a high resistance to dust; Piston pump, which inflict a fluctuating vacuum; Scroll pump, highest speed dry pump; Screw pump (10 Pa); Wankel pump; External vane pump; Roots blower, also called a booster pump, has highest pumping speeds but low compression ratio; Multistage Roots pump that combine several stages providing high pumping speed with better compression ratio; Toepler pump; and Lobe pumps.
These PD pumps use a mechanism in which they alternate the expansion and sealing off of a cavity. They are used mainly for lower vacuums and can also be paired off with momentum transfer pumps. In the case of pairing, the positive displacement pump starts the momentum and the momentum transfer pump continues the momentum with the higher vacuum.
Molecular or momentum transfer pumps remove air from a chamber by using blades that rotate at a high speed. They work best for higher vacuums. Entrapment pumps actually solidify gases with ionisation, chemicals or very low temperatures before moving them. Consequently, they are normally used for very high vacuums.
Applications for Vacuum Pumps
Vacuum pumps are used in a range of industries, including the manufacturing industry, printing, medical, marine, laboratories, farming, freeze drying, aircrafts, instrumentation, sewage systems and air conditioners.