How to Safely Stop and Restart Air Compressors: Proven Best Practices

If you need to reduce production and switch off your air compressors temporarily, we’ve consolidated a few of our top tips and tricks that discuss the best way to approach stopping and re-starting your compressor installation.

Stopping/Pausing Air Compressor Installation

Your air compressor system is going to be paused or stopped for a prolonged period of time, and you’re wondering how to accomplish this in the most effective and efficient manner possible. The below guidelines are based on compressor type!

• VSD Compressors. Carry out a program stop. Make sure the electrical power supply is left on to keep the capacitor bank charged and ready for restart.
• Water-Cooled Air Compressors. After stopping the compressor, be sure to isolate the water supply. This will stop condensate from forming inside the compressor element(s). Don’t forget to turn it back on at start up! Please also ensure that any air blast cooling systems are turned off.
• Oil-Free Z Compressors. These need the main drive shaft to be manually rotated via the motor drive coupling, 3 complete rotations, once a week. This is to prevent the low pressure and high-pressure compression stages from seizing up during a long period of down time. If the Z Compressor is a VSD version, please don’t forget to turn the power supply back on after turning the compressor over by hand. This will protect the inverter drive capacitors.
• Centrifugal / ZH Compressors. Carry out a program stop and leave the power supply on. They need to have the auxiliary oil pump left turned on electrically while the compressor is shut down. This will maintain the oil temperature and periodically start up the auxiliary oil pump to circulate warm oil around the bearings during long periods of downtime.

Restarting a Compressor Installation

Step 1 is turning off the power supply to the air compressor; from there you’ll remove the drive shaft protection guard and turn the drive coupling to check that the compressor is free to turn. If the compressor turns freely, re-fit the guard and turn on the power supply to the compressor. Next, turn on the cooling water and air blast cooling system (if the compressor is water cooled). Close the compressor air discharge valve and start the compressor, then slowly open the air discharge valve until the air pressure equalizes out between the compressor and the air net, then the compressor is back online.

Please note that if the air compressor is connected to a sequence controller, make sure the compressors are integrated onto the controller or optimizer.

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