A vacuum pump induces pressure difference between two sections by absorbing the gas or liquid molecules out of one space. The molecules of a matter move from a high-density area to the low-density region. A vacuum pump creates a vacuum by creating a pressure difference between two regions of space.
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Vacuum Pump| How Does It Work?
Vacuum pumps operate by moving the molecules of the liquid, air, and other gases from the vacuum chamber. Reduced pressure in the vacuum chamber makes it exponentially harder to remove additional molecules.
In industrial or scientific research vacuum systems require high vacuum to extreme high vacuum ranging from 10-3 Torr to 10-11 Torr. In order to commence this kind of operation, multiple numbers and types of vacuums are used covering a different range of pressures and sometimes operating in series.
Generally, there are two primary types of vacuum pump, Gas Transfer pump, and entrapment or trapping pump or capture pump. Gas Transfer pumps are also referred to as gas-displacement pumps. These types of pumps are mainly categorized either as positive displacement pumps and kinetic vacuum pumps.
The Positive Displacement Vacuum Pumps
The positive displacement vacuum pumps create low vacuums. These types of vacuum pumps create a vacuum by expanding the volume of a chamber. It creates a cavity and lets the molecules to flow out of the closed environment or space.
After that, the cavity is sealed and causes it to exhaust into the atmosphere. A positive displacement vacuum pump works like a diaphragm muscle that expands the chest cavity, causing the lungs to inflate.
The Roots Pump
The Roots pump is a type of dry positive displacement pump which is often used as a vacuum booster and designed to remove large volumes of gas. This type of pump transfers the gas in one direction through the pump.
It boosts the performance of a main or backup pump by increasing the pumping speed. They operate entirely contact-free and without sealing fluids in the working chamber.
Kinetic Transfer Pumps
Kinetic transfer pumps work on the principle of momentum transfer. There are many types of kinetic pumps, such as axial pump, liquid jet pump, diffusion pump, turbopump, molecular pump, turbomolecular pump, etc.
These pumps use mechanically moving parts by using high-speed blades or introduced vapor. Kinetic pumps generally don’t have sealed volumes, but it can achieve high compression ratios at low pressures.
An Entrapment Pump
An entrapment pump works using a chemical combination or condensation. This type of vacuum pump uses cold temperatures to condense gases to a solid or absorbed state. There are many types of entrapment pumps such as ion pumps, cryogenic pumps, sorption pumps, non-evaporative getter pumps, and titanium sublimation pumps, etc.
An Ion Pump
An ion pump uses the gettering principle. These pumps can reach pressures as low as 10−11 mbar under ideal conditions. An ion pump first ionizes the gas and produces a strong electrical potential causing powerful electrical fields to push the ions and ionize gases into a solid substrate.
Cryogenic Pumps
Cryogenic pumps work by condensation or freezing of the gas at very low temperatures. So, these machines generally use compressed helium, liquid nitrogen, or cryocooler. The cryogenic pump operates in the 10−3 to 10−9 Torr range.
Dry Vacuum Pump Working Principle
Dry Vacuum Pumps operate by gas condensation or a combination of gas compression and mechanical compression. Dry screw vacuum pumps have two adjoint screw rotors rotating in opposite directions. The cavity between these two rotors traps the medium and transfers it to the exhaust.
Dry vacuum pumps don’t use auxiliary liquid so it is used in fine chemicals and pharmaceutical plants to avoid product contamination. Combining the dry vacuum pump with roots-type mechanical boosters shorter pump-down times can be gained.
How to Vacuum Pump for AC Works
Vacuum pumps for air conditions remove unwanted gas, moisture, and chemicals from the refrigerant system. The pressure of the system is required to go under atmospheric pressure.
Generally, the vacuum pump is required to create a vacuum state of about 300 to 500 microns where the atmospheric pressure is about 759,999 microns. To measure the level of vacuum in the system electronic vacuum gauges are used. But you also can vacuum the AC system without using a pump.
What Is a 2 Stage Vacuum Pump?
In a 2-stage rotary vacuum pump, rotary compressors are used. When rotating, the pump keeps contact between the top of the rotary vane and the inner wall of the pump space by eccentric force and the tension of the spring.
For a better understanding of the working principle of a 2 stage vacuum pump, check the link below:
What Is a Micron Used in a Vacuum?
A micron is a unit used for measuring vacuum (negative pressure) as well as positive pressure. A Micron of mercury also called a micron is a very small unit of measure related to the displacement of a mercury column by atmospheric pressure. To be more precise, a micron is one-millionth of a meter of mercury displacement which is very small.
You can identify the quality of a vacuum from the micron number. Measuring in a micron vacuum scale, roughly 760,000 microns are equal to sea-level atmospheric pressure. It is a very accurate measurement unit that provides very precise results.
To Conclude
There are many categories of vacuum pumps that work differently but all of them have the same basic working principle. Here, we discussed the basic and brief principles of some types but to get a better understanding of the working mechanism, advantages, and drawbacks, a more detailed discussion is needed.
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