Compressor vs pump – what’s the difference? Here’s what to know about each one.
Compressors and pumps are often used interchangeably when discussing the transfer of fluid from one point to another. They are part of fluidic transmission systems that include fluid motors, etc. Pumps are machines that transform mechanical energy into working fluid energy, while compressors convert mechanical energy into the energy for compressing air.
Both machines achieve the goal of transferring fluid through a system but via different operating methods. Pumps can move gases and liquids, while compressors can only move gas since gases can be compressed. The only common feature between pumps and compressors is that they increase fluid pressure.
Let’s highlight what pumps and compressors are and the significant difference between the two fluid transmission system components.
What is a Compressor?
A compressor is a pneumatic, mechanical device that significantly boosts gas pressure by minimizing its volume. Compressors are generally classified into dynamic and positive displacement compressors. The latter is used exclusively – or nearly so – within the pneumatic industry. They work consistently based on a variable operating chamber like the system of a cylinder with a piston.
By reducing the volume of the chamber, the volume of air within it decreases accordingly, resulting in a significant increase in air pressure. Compressors work only with gases due to the latter’s natural ability to be compressed.
Pneumatic compressors are divided into two:
- Rotary (screw, lobe, scroll, vane) compressor
- Liquid ring compressor
- Reciprocating compressor
However, dynamic compressors are divided into axial and centrifugal compressors.
What is a Pump?
A pump is a machine designed to transfer mechanical energy from an electric-powered motor to the fluid passing through it. Pumps transport incompressible fluids – which could be pure or mixed with solid/semi-solid materials – of different temperatures, densities, and chemical properties ranging from aggressive to neutral.
As mentioned earlier, electric motors power pumps as well as internal combustion engines when it has to do with mobile hydraulics.
Pumps come in 2 unique categories:
- Centrifugal pumps
- Positive displacement pumps
Centrifugal pumps – such as turbopumps – provide power to the fluid within the rotor so that the mobile blades generate pressure force to the fluid. They are mostly used for low supply levels and relatively large flows, which is why they are not often employed in hydraulics.
On the other hand, positive displacement pumps work by increasing pressure and decreasing the chamber volume in order to move the fluid from one point to the other. As a result, they are generally used for high supply altitudes and relatively small flows.
Examples of positive displacement pumps include:
- Piston pumps (lift, force pump)
- Diaphragm pumps
- Rotary pumps (gear, wing, or coil pump)
The key operating parameters for pumps are:
- Flow rate (mass flow in kg/s or volume flow in m3/s)
- Efficiency (in percentages)
- Specific work (in J/kg)
- Power (in W)
The Differences Between Compressors and Pumps
Compressors and pumps are technical units with divergent characteristics. These are crucial as they help highlight the considerable differences between pumps and compressors.
Let’s check out 3 different characteristics that distinguish compressors from pumps, in no particular order:
1. Design Structure
Explaining the structural differences between compressors and pumps is very challenging. This is due to the enormous differences within each group. Therefore, both units are generally classified depending on the fluids used, principles of operation, application, construction, etc.
The basic parts of industrial compressors include a storage tank, intake filter, drain, valves, motor, etc. The basic components of industrial pumps are motor, volute, impeller, housing or casing, shaft, etc.
Moreover, industrial pumps are relatively simple in terms of design, with almost minimal vibrations during operations. But in many circumstances, industrial compressors take up a lot of space and vibrate more during operations.
2. Operating Principles
The operating principles of compressors and pumps are different. Pumps transport fluid (gases or liquids) from one point to another.
But compressors squeeze the volume of a gas and mostly pump it elsewhere. Although pumps use gases or liquids, compressors mostly work only with gases. This is because compressing liquids is practically impossible.
3. Application
Compressors and pumps have a wide range of applications across a wide variety of industries. Both machines are applied in unique technological constructions in large plants and factories and nearly every household in one form or the other.
Industrial plants also use pumps for various purposes. This is why different pumps, such as mining, irrigation, air conditioning, etc., exist.
Compressors are also used extensively in refrigeration technology. They have found great use in air conditioners, refrigerators, showcases, etc. Compressors also have extensive use or application within the processing industry. They are used in:
- Refineries
- Technical gas plants (O2, N2 bottles)
- Breweries (CO2)
Compressors are also used in pneumatic tools, automatics, etc., such as construction.
- Flowing Medium
Pumps are suitable for incompressible fluids like oil, water, and liquids. However, this doesn’t prevent them from functioning optimally on mixed fluid mediums, including gases. Pumps cannot lower the volume of fluids they transport from one point to the other.
But compressors are designed to work only with compressible substances like gas, air, vapor, etc. Therefore, they are capable of lowering the volume of these substances, which results in an increase in pressure.
Compressor vs Pump: Comparison Table
Here is a comparison table that highlights the differences between compressors and pumps:
| Compressor | Pump |
| Works only with gases, i.e., it transports gases only | It works with fluid, i.e., gases or liquids, i.e., it transports liquids and gases |
| There is volumetric change | There are zero changes in volume from the inlet to the outlet |
| There must be a significant pressure change | The pressure change is not necessarily essential |
| It has a storage capacity | There is no storage |
| It boosts the potential energy by pressuring gases into smaller volumes | It stimulates the kinetic energy of the fluid, resulting in an additional increase in pressure energy |
| It is more expensive than its counterpart | It is cheaper than its counterpart |
Conclusion
Compressors and pumps have only one thing in common: they increase the fluid pressure necessary for transporting fluid from one point to another via different operations. However, compressors only work with gases while pumps work with gases and liquids.
Pumps and compressors have different functions and are used for diverse purposes. Pressure also rises high in both cases during operations. They have tremendous applications in mining, metallurgy, construction, and process industries. They are also used domestically in air conditioners, washing machines, refrigerators, etc., in different ways.