Long-Term Deactivation & Recommissioning

Applies to: STS Series (5–30HP) · STSH Series · STSD · STSP · STSP2

▲ Attention When a compressor sits idle for extended periods, the airend rotors and bearings lose oil film. Ambient humidity can cause rust in the separator tank and airend, degrading oil lubricity. Operating without preparation after extended downtime may cause serious compressor damage.

Store the compressor on a flat, vibration-free surface in a closed environment protected from humidity, direct sunlight, wind, rain, and environmental contamination.

Deactivation Requirements by Duration

Duration	Before Deactivation	Before First Restart
3 months or more	Protect the airend: remove the suction hose at the suction control valve, open the suction flap, and fill the airend inlet with the same brand and type of oil until it reaches the top of the inlet mouth. Rotate the airend by hand in the direction of rotation to fully coat rotor pockets and bearings.	Drain excess oil from the airend down to the normal separator tank level before starting.
6 months or more	Perform the airend protection procedure above. If V-belt equipped: release V-belt tension.	Drain and replace all oil in the system with fresh oil of the same brand and type. Replace the separator element. Replace the air filter element. Re-tension V-belts (if applicable). After startup: monitor compressor operation and air dryer function.
12 months or more	Perform the airend protection procedure above. If V-belt equipped: release V-belt tension.	Drain and replace all oil. Replace the oil filter. Replace the separator element. Check scavenge line for rust. Replace the air filter element. Inspect cabin suction filters — replace if contaminated. Re-tension V-belts (if applicable). Inspect all hydraulic and pneumatic hoses for cracking or deformation — replace any damaged hoses. Have a qualified electrician inspect motor terminal box connections and all electrical cabinet connections for oxidation. After first restart, monitor and verify operation of: airend and seals, thermostatic valve, minimum pressure valve, suction control valve, pressure transmitters, thermometer/thermostat, and air dryer.

ℹ Note Parts consumed during recommissioning after extended storage are preventive maintenance items and are not covered under warranty.

Airend Protection Procedure (Applicable to All Durations)

1. Remove the suction hose at the suction control valve opening.
2. Open the suction control valve flap to the open position.
3. Add the same brand and type of compressor oil used in the unit through the suction control valve opening until oil reaches the top level of the airend inlet mouth.
4. Rotate the airend by hand in the direction of rotation so that oil fills the rotor pockets and bearing surfaces completely.
5. Reinstall the suction hose and secure with its clamp.

⚠ Warning Before performing the airend rotation step, ensure power is fully disconnected. Be careful not to get hands caught during manual rotation.

Related Articles

• First Start-Up & Commissioning Checklist
• Oil & Oil Filter Replacement
• V-Belt Inspection & Replacement

For assistance with deactivation or recommissioning, contact South-Tek Systems: [phone] or [e-mail]