Which is the better piston and screw compressor?
- May 16, 2023
Air compressors are important for many industrial operations. If you’ve ever considered purchasing air compressors, you’ve probably seen piston and screw compressors. There are many pros and cons to these different types of air compressors, but how do you decide or choose which one is right for your business?
Now, BISON break down the differences between piston and screw compressors and how to choose the right type for your needs.
What is a piston compressor?
Piston air compressors, also known as reciprocating compressors, work with the help of big pistons driven by a crankshaft. These are more traditional compressor types with lots of moving parts. This design feature leads to some of the most significant disadvantages of piston compressors, as it increases friction and heat. This variable makes it less reliable and more prone to failure while adding more maintenance requirements.
They are much larger than screw compressors, partly because they must be sized to produce more cubic feet per minute (CFM) of air than the application requires. This extra dimension is necessary for the compressor to cycle correctly and prevent additional wear.
What is a screw compressor?
Screw compressors use two helical screws to compress the air, but the key difference is that the screws don’t touch each other. With no contact, there is less wear and tear, reducing the need for maintenance and making the screw compressor more reliable. This mechanism offers additional benefits regarding heat production, noise level, size, efficiency and oil content in the output air.
One of the most valuable benefits of screw compressors is the ability to run continuously. It can operate without a duty cycle due to less risk of overheating and wear. This advantage also means that the compressor can be sized to meet the facility’s CFM requirements rather than purchasing a larger compressor to achieve the duty cycle. Since less valve cleaning is required, there is also less need to shut down the compressor.
In addition to eliminating oversizing, screw compressors are also designed to be smaller. Their compact nature and quieter operation mean they can be placed closer to shop floor applications, reducing the need for piping. The screw compressor has a one-way rotation to minimize vibration and can be mounted on the skids without additional foundations.
What’s the difference between a screw and a piston compressor?
The main difference between a screw and a piston compressor is how the air is compressed inside the unit. Screw compressors use two intermeshing helical screws, while piston type air compressors use pistons driven by a crankshaft. Another major difference is the moving parts since a screw compressor has two parts that don’t touch, while a piston compressor has many moving parts. Screw compressors run at lower temperatures and integrate a good cooling system. Also, what is the difference between these two different types of compressors – screw and piston?
application
| Applications of piston air compressors | Applications of screw compressors |
|---|---|
| Small machine shop | Food processing and packaging |
| Spray gun | Robot manufacturing |
| Tire shop | Mass production |
| Sandblasting | Conveyor system |
| Construction work | Hospitals |
| Purge cleaning | Paint production line |
| Residential use | Applications requiring very clean air |
| Hand power tools | Industries requiring continuous compressed air |
Duty Cycle
The percentage of time the compressor can run without the risk of overheating and excessive wear.
- Piston: limited
- Screw: 100%
Noise Levels
Screw compressors are much quieter than piston compressors, allowing for more flexible placement. If purchasing a piston compressor, you must ensure proper placement does not stress the worker’s hearing.
- Piston: 80+ dB(A) louder than an alarm clock
- Screw: 65 – 75 dB(A) similar to a toilet flush
Oil residue
When the oil used to lubricate the air compressor enters the air line. Screw compressors have an oil separation system that provides more effective oil removal. Piston compressors have higher oil concentrations because they lack an oil separation system, and the pistons and oil rings wear out.
- Piston: 10 ppm+
- Screw: 1 – 7 ppm
Flow
The ability of an air compressor to perform its duty continuously. Usually measured in CFM. Due to duty cycle requirements, piston compressors need to be much larger than your CFM requirements. Screw compressors can be closer to the size you require.
- Piston: 3 – 3.5 cfm/hp
- Screw: 4 – 4.5 cfm/hp
Moisture
The hotter the air, the more moisture it holds. The air’s ability to retain moisture doubles for approximately every 20°F increase in temperature.
Piston
- Internal operating temperature: 300 – 400°F
- Discharge temperature: 100°F+ above ambient
Screw:
- Internal operating temperature: 170 – 200°F
- Discharge temperature: 15 – 25°F above ambient
Cost
If you want to avoid spending a fortune, a piston compressor may be easier to come by. However, remember to factor in the costs associated with any special placement needs, such as soundproof enclosures and foundations. You may also want to do a cost analysis to see if other savings associated with a screw compressor can offset its additional initial cost.
- Piston: lower initial cost
- Screw: Lower operating costs
Usage
Piston:
- Intermittent use
- Lower cubic feet
- Higher pressure
- Smaller stores and manual applications
Screw:
- Continuous use
- Higher cubic feet
- High-volume and robotic manufacturing and delivery systems
- Applications requiring very clean air
Maintenance
How much maintenance does the equipment need in the first place? Piston compressor require more attention than screw compressors. Piston compressors require frequent maintenance and cleaning but can usually be done by existing staff, while screw compressor may need to be outsourced. Piston compressors also require more spare parts for repair, while screw compressors have fewwe parts.
The suitable compressor for your business must be carefully selected based on your organization’s unique operational needs and goals. A company that starts with piston compressors can outgrow, so it’s worth periodically revisiting your compressor costs and determining which one is right for your business.
Find the suitable compressor from BISON
There are a lot of compressors, and there are many factors when choosing one. Thankfully, the experts at BISON are well-versed in air compressors, no matter the design. We are happy to work with you through your setup and help you find a suitable compressor to achieve your business goals.
BISON is located in China and is an OEM wholesale supplier of all air compressors. Contact us today if you want to purchase different kinds of air compressors in bulk quantities at wholesale rates.
