Types of vacuum graphite furnace vacuum pumps

There are various types of vacuum pumps used in vacuum graphite furnaces, which can be classified into multiple types based on their performance characteristics, applications, working principles, and structural features. The following is a detailed summary of the common types of vacuum pumps in vacuum graphite furnaces:

1. Classified by performance characteristics and usage
Low vacuum pump
Vacuum pumps with a maximum pressure exceeding 102Pa.
Common low vacuum pumps include reciprocating vacuum pumps, rotary vacuum pumps, liquid ring vacuum pumps, jet vacuum pumps, and adsorption vacuum pumps.
Medium vacuum pump
A vacuum pump with a maximum pressure of 102~10 ^ -1Pa.
Common types include Roots vacuum pumps, multi-stage jet vacuum pumps, multi-stage rotary mechanical vacuum pumps, and high-speed rotary mechanical vacuum pumps.
High vacuum pump
A vacuum pump with a maximum pressure of 10-5Pa.
Common high vacuum pumps include various diffusion pumps and molecular pumps.
Ultra high vacuum pump
Vacuum pumps with a maximum pressure below 10 ^ -5Pa.
Ultra high vacuum pumps mainly include various ion pumps, low-temperature pumps, etc.
2. Classified by working principle and structural characteristics

Mechanical volumetric vacuum pump
The pumping action is achieved by periodically changing the working volume of the pump chamber through mechanical motion.
There are reciprocating vacuum pumps and rotary mechanical pumps (including rotary vane, screw, Roots, liquid ring, etc.) belonging to this type of pump.
Except for mechanical booster pumps, these types of pumps can generally be used independently.
Jet type vacuum pump
There are no mechanical moving parts, mainly relying on high-speed jets through nozzles to evacuate.
There are steam jet pumps, air jet pumps, water jet pumps, and various diffusion pumps belonging to this type of pump.
This type of pump has a simple structure, reliable operation, long service life, easy maintenance, and is widely used.

3. Common types and characteristics of vacuum pumps
Dry screw vacuum pump
An oil-free vacuum pump compresses gas from the inlet to the outlet by rotating two interlocking screws inside the pump chamber.
It has the advantages of no oil pollution, low noise, and low vibration, and is particularly suitable for industries such as semiconductors and electronics that require high cleanliness.
It also has strong corrosion resistance and reliability, and can operate stably in harsh environments.
Oil seal rotary vane vacuum pump
The most common type is the oil vacuum pump, which seals various working clearances through the circulation of oil, while also providing cooling and lubrication.
Can provide high vacuum degree and high pumping rate.
More suitable for applications that require high vacuum and high pumping rates, such as metallurgy, chemical engineering, materials research, and other fields.
But regular maintenance is required, such as replacing oil and filters, to ensure performance.
Oil-free vortex vacuum pump
It is mainly composed of two asymmetric vortex disks, one fixed and the other driven by an eccentric shaft to rotate around the fixed vortex disk.
It has the advantages of environmental protection, high efficiency, and low noise.
Roots vacuum pump
A positive displacement vacuum pump that uses two “8” – shaped rotors to rotate inside the pump chamber, drawing gas in from the inlet and compressing it to the outlet.
It has the advantages of large pumping volume, simple structure, and easy maintenance.
Widely used in industries such as chemical and food.
However, due to the presence of pulsation during the pumping process, it may not be suitable in certain situations where high stability is required.
Diffusion pump
A vacuum pump that utilizes steam flow to drive gas flow.
Mainly used in high vacuum fields, it can achieve extremely high vacuum degrees, but the pumping rate is relatively low and requires preheating time.
Usually used in fields such as scientific research and semiconductor manufacturing.
Molecular vacuum pump
A vacuum pump that utilizes the difference in collision probability between gas molecules and the inner surface of the pump in a molecular flow state to achieve pumping.
It has the advantages of low ultimate pressure and fast pumping speed, especially suitable for applications in high vacuum fields.
But it is more sensitive to gas types and temperatures, and has a higher price.

In summary, there are various types of vacuum pumps used in vacuum graphite furnaces, and the selection should be comprehensively considered based on specific application requirements, working environment, and budget factors.