GB/T 37468-2019 in English

Analysis of the core content of the standard

Key technical requirements

The standard stipulates that the direct radiation meter must adopt the thermoelectric induction principle, and its collimated light tube structure must meet the following requirements:

• Half-opening angle α: 2.5°±0.1°
• Bevel angle β: 1°±0.1°

The incident window must be made of optical glass with a thickness deviation of ≤0.1mm and a visible light transmittance of ≥90%.

Test Method Summary

Standard Evolution Background

This standard unifies the domestic direct pyrheliometer production specifications for the first time. The main technical improvements include:

• The opening angle is reduced from the traditional 10° to 5°, which meets the WMO recommended value
• New electromagnetic compatibility requirements (electrostatic discharge immunity ≥4kV)
• Clearly distinguish between primary and secondary instrument accuracy levels

Implementation suggestions

Manufacturers should pay special attention to:

1. Environmental testing should at least include:
   - Temperature cycle (-40℃~+60℃)
   - Alternating damp heat (2 cycles)
   - Sinusoidal vibration (5m/s²)
2. Factory inspection must be subject to full-item Group A inspection
3. Annual stability testing should establish a continuous monitoring file