What is an oil-injected screw compressor?

Want to know more about oil-injected screw compressors or liquid-injected screw compressors?

Estimated time to read: 2 minutes

April 24, 2023

What are screw compressors?

Air compressors generally compress air in one of two different ways. The first is to use a piston that squashes – or compresses – the air into a smaller and smaller area. You do this with what is called – believe it or not – a piston compressor.

The other method? It uses two screws, or rotors, with the thread or teeth on one screw pressing into the gap between the threads or teeth on the other screw. This compresses the air in the gap between the threads.

The gap between the threads becomes smaller and smaller as the air travels further along the screws. This means it is compressed more and more. Clever stuff. What is the name of this type of compressor? There are two usually used. First up: screw compressor. If you’ve been following, you’ll understand why it’s also known as a rotary-screw compressor.

What is an oil-injected screw compressor?

In the screw injector, the screws press and rub against each other. And when this happens, it results in heat. Heat isn’t always a good thing. Especially not in this case. You stop things from becoming too hot with a coolant.

In the case of a screw compressor, you usually use oil as a coolant. The oils circulate between the screws and around the rest of the compression chamber. Everything is kept that little bit cooler at a comfortable 80°C. Your compressor will maintain this temperature regardless of load and pressure.

There are other benefits too. When there’s oil circulating around, your compressor will operate more quietly and suffer less wear and tear. Exactly what you want.

However, with oil circulating around, you end up with oil in your compressed air. There’s no need to worry though. Most oil-injected screw compressors have oil separators. These are super-effective systems for removing oil from compressed air. After the oil is out, the air goes through after-coolers before continuing its journey through your compressed-air network.

Principle of liquid injected screw compressor diagram

Want to know more?

Wondering what the difference between oil-injected and oil-free air compressors is? Would you like to know more about oil-injected screw compressors? Are you thinking of buying one for Valentine’s Day? Get in touch with us at ALUP.

As well as a range of oil-injected screw compressors and other air compressors, we have plenty of experience, insight and knowledge that we would love to share with you.

Learn more by going through our compressor guide:
< The Adsorption Dryer
About Compressed Air >

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