GB/T 33706-2017 in English

Analysis of the core framework of the standard

Detailed explanation of key technical requirements

Optical system design

Standard requirements: The geometric parameters of the collimation tube must meet the following requirements:

• Half-opening angle θ: 2.5°±0.1°
• Bevel angle δ: 1°±0.1°

This design ensures accurate measurement of the 5.7° field of view and effectively eliminates stray light interference.

Environmental adaptability requirements

Implementation suggestions

Calibration cycle management

The standard stipulates that the calibration cycle of direct radiation meter is 2 years, but it is recommended to shorten the cycle in the following situations:

• Highly polluted environment (PM2.5＞75μg/m³)
• Coastal high salt fog area
• In strong radiation area with annual radiation>1800kWh/m²

Maintenance points

Key maintenance steps:

1. Check the cleanliness of the quartz window daily (wipe with anhydrous ethanol)
2. Verify the desiccant status every month (replace when the color-changing silica gel＞1/3 turns red)
3. Check the coating integrity of the sensing surface every quarter (blackness coefficient change ≤3%)