Must the air dryer tower be started when starting the air compressor?

Operational Interrelationship Between Air Compressors and Desiccant Dryers

When the air compressor starts, whether the desiccant dryer must be started simultaneously depends on the system design objectives and the required air quality. If downstream equipment or processes have strict limits on the compressed air dew point and oil‑water content, the dryer should be interlocked with the compressor to prevent untreated air from entering the distribution network.

Necessity of System Interlocking

In most industrial applications, the air compressor and desiccant dryer are interlocked via a PLC or relay: the compressor start signal initiates dryer operation; upon shutdown, the dryer is delayed to ensure the integrity of the adsorbent regeneration. Non‑interlocked operation may lead to condensate accumulation, pipeline corrosion, or failure of pneumatic components.

Explanation of Exceptions

In certain temporary commissioning, low‑load testing, or short‑term air‑use scenarios, the desiccant dryer may be manually bypassed. However, the following conditions must be confirmed: 1) there are no precision instruments or spray‑coating end devices downstream; 2) ambient humidity is low and the operating time does not exceed 30 minutes; 3) risk‑mitigation measures are in place. Prolonged bypass of the dryer will accelerate the degradation of downstream treatment equipment.

Operation and Maintenance Recommendations

• Verify that the interlock logic diagram in the system drawings matches the actual wiring.
• Regularly validate the dryer’s start‑stop response times and confirm that the dew point meets specifications.
• Clearly specify in the operating procedures the start‑stop sequence for the “air compressor–desiccant dryer” pairing, as well as the steps for handling abnormal situations.