How much is the dryness of compressed air?
The dryness requirements of compressed air vary according to the specific application scenario, but generally speaking, the dryness requirements depend on the content of water vapor in the compressed air, which are usually measured by the dew point temperature. The following is a detailed analysis of the dryness requirements of compressed air: 1. Definition of dew point temperature
Dear point temperature refers to the temperature when water vapor in the air begins to condense into liquid water under a certain pressure. When the temperature of compressed air drops to the dew point temperature, the water vapor in it condenses into water, which can adversely affect equipment and processes using compressed air.
2. Classification of dryness requirements
According to the national standard “GB/T 13277.1-2023” and industry practice, compressed air dryness is usually divided into different levels, and each level corresponds to a specific dew point temperature range. The following is the classification of compressed air dryness according to dew point temperature:
| Level | Dew point temperature range (℃) | Application scenario example | |
|---|---|---|---|
| Level 1 | -70℃ | Precision instruments, such as industrial robots, fully automatic assembly lines, automotive spraying, etc. | |
| Level 2 | -40℃ to -70℃ | Same as above, there are extremely high requirements for dryness | |
| Level 3 | -20℃ to -40℃ | Easy to high requirements in the occasions where dryness is very high | |
| Instrument applications, pneumatic tools, etc. | |||
| Level 4 | 3℃ to -20℃ | td> | General uses, such as purge, pump, etc. |
| Level 5 | 7℃ to 3℃ | Actually, the requirements for dryness are not high | |
| Level 6 | 10℃ to 7℃ | Same as above, or as an occasion for preliminary dehumidification |
3. Drying requirements for specific application scenarios
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Precision instruments and industrial applications:
- Industry such as industrial robots, fully automatic assembly lines, automobile spraying and other industries, the pressure dew point of compressed air is relatively high, usually between -40℃ and -70℃, that is, the above-mentioned level 1 or level 2 standards. This is to ensure the proper operation of these precision instruments and equipment and avoid moisture causing corrosion or failure to them.
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Instrument Application:
- Compressed air used in instruments, its pressure dew point is generally required to be below -40℃ to ensure the accurate operation of the instrument and extend the service life. The instrument has high requirements for compressed air dryness because moisture may cause inaccurate meter readings or damage to internal components.
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General Use:
- For some simple purge or pump uses, the dryness requirements of compressed air may be less stringent, and may only need to meet the Level 4 or Level 5 standards. These occasions require relatively low dryness on compressed air, but it is also necessary to maintain a certain dryness to avoid adverse effects of moisture on the equipment and process.
4. How to achieve the required dryness
In order to obtain the required dryness, compressed air drying equipment is usually required, such as refrigeration dryers, adsorption dryers, etc. These devices achieve the desired dew point temperature by reducing the moisture content in the compressed air.
- Refrigerated dryer: It is suitable for situations where the pressure dew point is above 0°C. By reducing the temperature of the compressed air, the water vapor in it condenses into water and discharges.
- Adsorption dryer: It is suitable for situations where the pressure dew point is between -20℃ and -70℃, adsorbing moisture in compressed air through adsorbents (such as activated alumina, molecular sieve, etc.), thereby achieving a lower dew point temperature.
5. Summary
The dryness requirements of compressed air vary according to the specific application scenario, but generally speaking, dew point temperature is a key indicator for measuring dryness. When selecting and using compressed air drying equipment, the required dryness level needs to be determined according to actual needs and a suitable drying equipment is selected to achieve the desired dew point temperature.
