International Common Standards: ISO 8573-1
In the industrial sector, the most authoritative and widely adopted international standard for assessing the quality of dried compressed air isISO 8573-1. This standard categorizes contaminants in compressed air into three main types: solid particles, moisture, and total oil content. With regard to dryness, the standard primarily addresses this throughPressure dew pointTo classify moisture content levels.
Moisture Content and Standard Dew Point Pressure Values
According to ISO According to the provisions of 8573-1, the moisture level in compressed air ranges from… Class 1 To Class 6 They decrease sequentially, with lower values indicating drier air. The following are the standard pressure dew point values corresponding to each grade:
- Class 1: Pressure dew point ≤ -70℃
- Class 2: Pressure dew point ≤ -40℃
- Class 3: Pressure dew point ≤ -20℃
- Class 4: Pressure dew point ≤ +3℃
- Class 5: Pressure dew point ≤ +7℃
- Class 6: Pressure dew point ≤ +10℃
Note: If the supplier claims to meet a standard higher than Class 1 More stringent standards are typically labeled as Class 0 However, this requires the supplier to provide specific test data and assurances; the standard itself does not stipulate such requirements. Class 0 the specific numerical value.
Common Application Scenarios and Tier Selection
Different industrial applications have widely varying requirements for the dryness of compressed air; when selecting standard values, it is essential to take actual operating conditions into account.
- Class 2 (Dew point ≤ -40℃）This is a common instrument air standard, suitable for moisture-sensitive precision pneumatic control components, paint spraying, and the general electronics manufacturing industry, effectively preventing pipeline icing and component corrosion.
- Class 4 (Dew point ≤ +3℃）Typically achieved by refrigerated air dryers, it is suitable for general factory pneumatic tools, material handling, and routine purging applications with modest moisture‑content requirements.
- Class 1 Or betterIt is suitable for specialized industries with extremely stringent air quality requirements, such as pharmaceuticals, food and beverage processing, and high-end semiconductor manufacturing, and must be equipped with either an adsorption dryer or a membrane dryer.
National Standards and Measurement Precautions
In China,GB/T 13277The series of standards has been adopted in an equivalent or modified manner. ISO The 8573 series standards maintain basic consistency with international standards in their classification of moisture and dew point levels. When measuring and verifying standard values, a calibrated, dedicated dew-point instrument must be used. During measurement, ensure that the dew-point instrument is installed at a sampling point downstream of the dryer and that the gas flow rate and pressure comply with the instrument’s measurement specifications to guarantee data accuracy.