For data center air conditioning systems (especially precision air conditioners or CRAC units), the vacuum level requirement mainly depends on whether the system has a compressor (with refrigerant) and the manufacturer’s specifications. Here are the industry-standard guidelines:
General Standard
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Target vacuum level:
500 microns or lower (≈0.66 mbar, ≈66 Pa)
This is the common HVAC and data center standard to ensure the system is almost free of moisture and air. -
High Standard / Best Practice:
300 microns or lower
Recommended for large refrigeration systems or those sensitive to moisture (e.g., low-temperature systems, long piping).
Why 500 microns?
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A refrigeration system must be free of moisture and air; otherwise, it can cause:
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Freeze-up (ice blockages)
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Acid formation leading to compressor damage
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Reduced heat transfer efficiency
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Below 500 microns means the system pressure is close to a true vacuum, and most residual moisture has been removed.
Vacuum Procedure Recommendation
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Pull down to about 1500 microns first, hold for a few minutes to check for leaks.
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Then pull down to 500 microns or lower, and hold for 10–15 minutes without rising.
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If the pressure rises quickly after stopping the pump, there’s likely a leak or residual moisture.
CRACУ
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500 micron ≈0.66 mbar≈66 Pa
HVAC -
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300 micron
е -
500 micron
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Ч
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500 micron ±
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轨
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1500 micronй
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500 micron 10~15
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