Bringing a compressor back online, such as following a holiday shutdown, requires some preparation and care to ensure the system is safe and functional. By sharing these tips, the staff at ESA will help you get your compressed air system back online after a shut down.

Was it properly shut down?

In order to start back up again without problems, a compressed air system must be properly shut down first. If a system is located outdoors and will sit in cold temperatures, it should be prepared to handle cold temperatures without problems. For starters, moisture can accumulate in the machine’s lubrication systems and lines. The compressor will naturally remove moisture when running, but the moisture accumulates and can freeze in the lines if the temperatures dropped. Additionally, letting air compressors sit with used oil can cause rust and corrosion from contamination.

When was it last serviced?

If the compressor was last serviced more than six months ago, it will be due for a full service to ensure that it is working properly. The system’s service should include replacing the air filters and oil, as oil can become compressed in cold temperatures, which in turn causes it to gather moisture or lose its viscosity. Additionally, oil filters can become brittle if the machine sits for extended periods of time without running, which causes oil leaks as a result. Sediment can accumulate in the oil filters, causing them to become fouled and warranting replacement. The motor bearing grease should also be changed if the air compressor is overdue for a service appointment.

What is the ambient temperature?

If temperatures drop below freezing, air compressors may need some extra care before restarting. If the ambient air temperatures fell below 40°F when the system was offline, it should be warmed up again before it goes online. This can be accomplished simply by putting a space heater in the room to avoid further wear and tear or a cold start.

Can it be supported by infrastructure downstream?

The oil and water separators may suffer if they are not used during a shut down. The valves must be slowly reopened in the order that they receive air so that the air is slowly worked through the system. You should check the system for compromised fittings and leaks before bringing it back online, too. Rather than shocking the system with air, valve off the compressor at the primary source and introduce air slowly at a designated control point.

Has the air end been primed?

The air compressor’s service manual contains instructions for priming the air end. Generally, this requires removing the inlet valve and applying oil directly to the air end.

By following the proper steps, you can safely bring air compressors back online after a shut down. Contact for assistance and more information.

Arthur Pue

Arthur Pue is the President of Engineering Sales Associates. Connect with him on LinkedIn.