The Piston Compressor
Learn more about air compression and the different types of displacement compressors we know today. Here we’re talking about oil-lubricated and oil-free piston compressors.
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What Type of Compressor Do I Need?
Once you have the size of the air compressor figured out, the next thing to do is to decide on the type of compresor you will need for your application. Let us take a look at two of the most popular options available.
Some questions to ask yourself
When choosing the right type of compressor, you should ask yourself these questions:
- What is the application
- How much flow does my facility/workshop use
- What pressure is needed within the facility
- Do I need clean/dry air (use of dryer and filters)
- How many hours per year does my compressor operate
- How many shifts do I run per day
- Is there fluctuation in flow demand between shifts (if so, a VSD compressor could be a good option and offer great savings)
- Are there any plans for future expansion
The piston compressor
The most economical and least expensive air compressor available is the piston or reciprocating air compressor. This is a very simple and robust air compressor that is used in many small shops. You can oftentimes find the piston compressor in small work and machine shops, body shops, tire shops and small manufacturing facilities. Piston compressors are relatively easy to maintain and as previously mentioned require minimum investment. Considering that piston compressors are economical, there are some drawbacks that should be taken into account before making a decision.
Piston compressors are only meant for intermittent use, meaning that the compressor can only work at about 50-60% of its duty cycle. This means it will run 30 to 35 minutes, every hour during its duty cycle. These units require proper cooling time between cycles, otherwise they will overheat and or fail. It is also important to understand that piston compressors put out a lot of oil downstream and if not treated properly they can damage the machines that utilize the compressed air. Lastly, piston compressors tend to be very loud when in operation, which can be hard on the employees working in close proximity to the compressor.
The rotary screw compressor
If your operation requires constant compressed air supply, you should consider a rotary screw air compressor. Unlike the piston compressor, rotary screw air compressors are used for any operations that require up to a 100% continuous duty cycle and are built for long lifetime of reliable operation. Rotary screw air compressors are a great alternative fot the piston units and there are various available, depending on your needs and budget. One of those options is the ability to integrate a dryer into the package, which is ideal for the applications that require clean and dry air.
Furthermore, smaller screw compressors can be tank mounted allowing for additional storage capacity which, coupled with an integrated dryer, allows for plug and play installation. This makes it ideal if you have limited space at your facility and if you wnat to save on installation costs. Depending on your budget, there is a screw compressor for everyone, ranging from basic design, usually available on smaller kW/HP ranges, all the way to Variable Speed (Frequency) Drive (VSD) units. Those are more expensive but typically make up for the initial cost with energy savings.
Variable Speed Drive compressors are a great option for any facilities that have fluctuation in their flow demand. This is especially true if your facility operates multiple shifts during the day and where flow demand increases and decreases throughout the day. Considering that compressed air usage can be costly, as it accounts for over 70% of Total Cost of Ownership in electricity costs, utilizing VSD technology can help you achieve savings of 35-50%. Depending on size of the compressor, the savings can range from $100s to $10,000s annually or more. VSD air compressors match the output to the demand that is needed. In simpler terms, the compressor can sense how much flow is being used and adjusts its speed accordingly, to only allow the output that is needed. On slower production days, during second or third (skeleton shifts?) the VSD technology comes especially handy, as it eliminates the waste of electricity and therefore saving money. VSD air compressors are becoming the norm rather than the exception, with many customers enjoying the annual energy savings and having the ability to reinvest the money into other assets.
Other questions when buying a compressor
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