8.1.1 Wind Speed

This section provides guidance for procurement of anemometers (i.e., mechanical wind speed sensors employing cups or vane-oriented propellers) which rely on the force of the wind to turn a shaft. Guidance for the procurement of remote sensors for the measurement of wind speed is provided in Section 9. Other types of wind speed sensors (e.g., hot wire anemometers and sonic anemometers) are not commonly used for routine monitoring and are beyond the scope of this guide. An example performance specification for an anemometer is shown in Table 8-1.

Table 8-1 Example Performance Specification for an Anemometer
Range	0.5 m/s to 50 m/s
Threshold 1	0.5 m/s
Accuracy (error)1,2	(0.2 m/s + 5% of observed)
Distance Constant1	5m at 1.2 kg/m3 (at std sea-level density)
1 As determined by wind tunnel test conducted on production samples in accordance with ASTM D-22.11 test methods 2 aerodynamic shape (cup or propeller) with permanent serial number to be accompanied by test report, traceable to NBS, showing rate of rotation vs. wind speed at 10 speeds.

The procurement document should ask for (1) the starting torque of the anemometer shaft (with cup or propeller removed) which represents a new bearing condition, and (2) the starting torque above which the anemometer will be out of specification.; when the latter value is exceeded, the bearings should be replaced.

The ASTM test cited above includes a measurement of off-axis response. Some anemometer designs exhibit errors greater than the accuracy specification with off-axis angles of as little as 10 degrees. However, there is no performance specification for this type of error at this time, due to a lack of sufficient data to define what the specification should be.

8. QUALITY ASSURANCE AND QUALITY CONTROL
8.1 Instrument Procurement 
     8.1.1 Wind Speed 
     8.1.2 Wind Direction  
     8.1.3 Temperature and Temperature Difference 
     8.1.4 Dew Point Temperature 
     8.1.5 Precipitation 
     8.1.6 Pressure 
     8.1.7 Radiation  
 8.2 Installation and Acceptance Testing
     8.2.1 Wind Speed 
     8.2.2 Wind Direction  
     8.2.3 Temperature and Temperature Difference 
     8.2.4 Dew Point Temperature 
     8.2.5 Precipitation 
     8.2.6 Pressure
     8.2.7 Radiation
  8.3 Routine Calibrations  
      8.3.1 Sensor Check  
      8.3.2 Signal Conditioner and Recorder Check  
     8.3.3 Calibration Data Logs 
     8.3.4 Calibration Report  
     8.3.5 Calibration Schedule/Frequency 
     8.3.6 Data Correction Based on Calibration Results  
  8.4 Audits 
     8.4.1 Audit Schedule and Frequency  
     8.4.2 Audit Procedure 
     8.4.3 Corrective Action and Reporting 
  8.5 Routine and Preventive Maintenance 
     8.5.1 Standard Operating Procedures  
     8.5.2 Preventive Maintenance  
 8.6 Data Validation and Reporting  
     8.6.1 Preparatory Steps 
     8.6.2 Levels of Validation  
     8.6.3 Validation Procedures  
     8.6.4 Schedule and Reporting
  8.7 Recommendations