Now that you have figured out what size air compressor you need, you will need to choose what type of air compressor you need.
Likely you will be choosing between two air compressor types – piston and rotary screw. Your decision will depend on your application.
When you are researching air compressor types there are a few things you need to consider:
- What are your application requirements?
- Air flow utilization?
- What are your pressure needs?
- What air quality is needed?
- Do you need dryers/filters?
- What is the usage time throughout the day?
- Does your air flow demand fluctuate?
- Are you hoping to expand in the future?
Piston air compressors
The least expensive compressor option is the piston or reciprocating air compressor. They are simple and robust. Piston compressors are mostly found in work, machine, body, and tires shops as well as light manufacturing facilities.
Piston compressors are easy and inexpensive to maintain. However, there are a couple of drawbacks that are important to consider. Piston air compressors are only meant for intermittent use. They can only work about 50-60% of their duty cycle. This means a piston compressor can only run for 30-35 minutes every hour and requires downtime to cool between cycles, otherwise they will overheat or break.
Piston compressors also create a lot of downstream oil. If it is not treated properly, the oil can damage machines utilizing compressed air.
Another downfall for piston compressors is they tend to be loud when operating making it hard on employees working near the machines.
Rotary Screw Compressors
Rotary screw compressors should be considered if your application requires constant compressed air supply. These compressors are designed and built for reliable, all-day operation.
With a rotary screw compressor there are a lot more options, depending on your needs and budget, you can get a variable speed drive (VSD) or fixed speed engine models. Most rotary screw equipment can also be built with an integrated dryer for clean, dry air.
In addition, small screw compressors can be tank mounted allowing for additional storage capacity and saves on space and installation costs. When it is coupled with an integrated dryer, the installation is plug and play.
Variable speed drive (VSD)
A VSD air compressor is generally the most expensive option in terms of the initial investment, however VSD compressors are highly efficient. Considering energy costs make up to 80% of the operating costs of any air compressor, they usually pay for themselves. In some cases, you can save up to 60% with the latest generation VSD models compared to fixed speed compressors.
A VSD compressor is the best choice if your facility has fluctuation air demand. Perfect for facilities operating multiple shifts a day, where air flow increases and decreases. A VSD engine is designed to match output to the required demand.
Fixed speed compressors are designed for optimal performance and only run at one speed throughout the day. This means you will receive the same air pressure and it will not change with the demand. However, fixed speed compressors make for a better option than a piston compressor if you need 100% air flow.
Within this article we touched on the difference between piston compressors and rotary screw compressors, if you are still not sure which one is the best fit for your facility contact an expert today.
Read part one about choosing the right compressor size.
Read part three about the difference between oil-injected and oil-free compressors.