Open the cold dryer first or open the air compressor first

When starting the compressed air system, the correct operating sequence and equipment characteristics need to be understood in conjunction with the working principle of the oil-free water-lubricated air compressor (or water-lubricated air compressor). Here are the step-by-step instructions:

1. Start-up sequence principle
the air compressor should be started first, and the cold dryer should be started after its operation is stable. This is because:

• the water-lubricated air compressor realizes the lubrication and cooling of the compression process through water circulation, and it takes a short time to establish the internal water pressure balance after starting. If the cold dryer is not running at this time, the compressed air temperature is high, but the water lubrication system itself can take away part of the heat through the circulating water to avoid overheating of the equipment.
• The cold dryer needs to work efficiently after the compressed air temperature drops to a reasonable range (usually determined by the air compressor exhaust temperature). If the cold dryer is turned on first, the high-temperature air may exceed its processing capacity, resulting in abnormal refrigerant pressure or internal condensation risk.

2. Special considerations for water-lubricated air compressors

• water circulation preheating: When the water-lubricated model is started, the water pump will first establish a circulation, and the water film in the compression chamber needs about 30 seconds to 1 minute to form a stable lubricating layer. The exhaust temperature may be slightly higher at this stage, but no additional cooling equipment is required.
• Water content control the air discharged from the water-lubricated air compressor has a high humidity (due to the participation of water in the compression process) and needs to be further dried by the cold dryer. If the order is reversed, the cold dryer may start and stop frequently due to the fluctuation of intake air temperature or excessive water content, affecting the life.

3. Operation steps detailed
① start the air compressor:

• check that the waterway valves are open to ensure smooth water flow.
• After the inching start, observe the water pump pressure gauge and confirm that the water pressure is stable within the normal range (usually 0.2-0.5MPa).
• When the exhaust temperature stabilizes (about 5-10 minutes), the compressed air temperature is suitable for subsequent treatment.

② start the cold dryer:

• turn on the power supply of the cold dryer and allow it to pre-cool for 3-5 minutes (this step is required for some models).
• Slowly open the air inlet valve of the cold dryer to avoid the pressure fluctuation caused by the instantaneous impact of compressed air.
• Check whether the drainer of the cold dryer works automatically to ensure that the condensed water is discharged in time.

4. Reverse operation of shutdown sequence
when closing the system, stop the air compressor first, and then close the air dryer after the compressed air pressure drops to zero. This is to prevent the formation of negative pressure inside the cold dryer, resulting in water back into the compressed air pipe.

Summary: The coordination between the water-lubricated air compressor and the cold dryer shall follow the principle of "moving first and then cooling"-first let the air compressor establish a stable water lubrication and temperature balance, and then optimize the air quality through the cold dryer. This sequence can not only protect the equipment, but also ensure the long-term reliable operation of the compressed air system.