Rotary-Screw Air Compressors

How they work, what you need, and how you maintain them

Before we dive into rotary-screw air compressors, it’s important to understand that there are many types of air compressors. Air compressors are used in a range of applications from industrial, manufacturing, construction, and more. A screw-compressor is more often than not, the right tool for manufacturers, shops, and construction crews.

The most common air compressor is a screw compressor. These machines work well for most applications of compressors. They’re quiet, powerful, and effective. The right screw compressor can make your business more productive and more efficient, as well as improve the work environment for your team.

A rotary-screw air compressor works on suction, and it responds to demand. At start up, a screw compressor will turn on and build up pressure to whatever your set point or facility demand. Then the compressor will turn itself off and wait. When the pressure drops off, the screw compressor will turn itself back on and build the pressure back up to the set point. This model of operation is one of the benefits of a screw compressor, as it makes sure the compressor keeps up with the demand, but doesn’t waste energy and create unnecessary noise. For example first thing in the morning, a facility may not be using a lot of air because employees are not using tools, so the screw compressor is not going to cycle as much. Later on in the afternoon, as production ramps up, there’s a lot of demand for air, and your compressor may turn on and remain running for the rest of the day if the demand is that high. The machine responds to your working needs by keeping up with demand.

The amount of power coming from your air compressor is a factor that varies depending on the size of the compressor. There are a broad range of sizes and options - Variable speed drive and Fixed speed drive . The compressor you choose should be sized to your facility and your demand.

At Chicago Pneumatic, we have two different types of compressors. We have the piston compressors, and then we have our screw compressors. We usually recommend a screw compressor. A screw compressor is a better option for your higher CFM requirements. Plus, a screw compressor is more efficient, quieter, cleaner and it has lot of other benefits. There is a slight cost associated with these benefits, of course, but we feel the return is well worth it. When a piston compressor turns on, it runs full bore, and when the demand is met, it turns off. A screw compressor is smarter, so to speak. It can turn on and run slowly if there’s not much demand, and it can increase its output as demand requires.

First, you will need to have a knowledgeable sales representative on site to accurately assess your application and need. That is the most important thing when purchasing a compressor. • You don’t want to get a compressor that’s too small, as it will struggle to keep up with demand. • You don’t want to get a compressor that’s too large, as it won’t cycle as much as it needs to. Compressors like heat; they like to be run. If a compressor is not cycling as much as it needs to, then you could experience condensate build up in your oil, and there are other issues that could arise, as well. In exploring your options, you will want to ask questions like: • How much air are you going to use? • Will you need a dryer? • What is the planned location of the compressor? • Do you have any plans of growing your business? You will also want to look at the warranty and at serviceability of the air compressor. This is not only in concern to the compressor itself, but to the company from which you’re buying it. • Is the company going to be there to support any questions or issues you may have? • How will you service and maintain the machine?

Maintenance is the most important factor to the continued performance of your air compressor. Some of our screw compressors out there are older than ten years and have over 30, 40, or 50 thousand hours on them and still running strong. Other than regular maintenance, you want to make sure the compressor is in a good, clean environment. Although compressors do like heat, they can’t be in an environment that’s too hot. Confined spaces need to have ventilation. In some cases, HVAC needs to be ducted into the mechanical room where the compressor is sitting so that the equipment doesn’t overheat. You want to keep filters clean, coolers clean, and just check the air compressor regularly and follow your instruction manual. You want to stay on top of everything from draining the moisture and servicing the machine accordingly. Anything neglected on the air compressor, like with any machine, is going to require more maintenance in the future, so you want to observe regular maintenance intervals and follow some maintenance tips. Getting the compressor sized right for the application is also important. If you have a compressor that’s under-sized, it’s going to run more, and the demand is going to be harder on the equipment. That’s why it’s important to get the right piece of equipment from the start.

In general, you should plan on servicing your rotary-screw air compressor once a year. Though, servicing needs for compressors vary based on a list of factors. Your machine may need servicing at 2,000 hours of usage, or it may not need servicing until 4,000 hours. The service may consist of a simple filter change, or it may be a complete filter change and an oil change (which varies based on oil type used). Your knowledgeable sales representative will help you determine the best compressor for you, the needed oil type, and the appropriate service schedule. If you have the inhouse expertise and time to service the compressor yourself, then you can use CP as a resource to answer any questions you have along the way. Or, we can connect you to a dealer who can do a one-time service and even set you up on a service schedule.