The normal test of a device shall be made at the maximum discharge flow rate and include flow rates down to what value?

The correct answer is that the normal test of a device shall be made at the maximum discharge flow rate and include flow rates down to 1/2 times the sum of the maximum discharge flow rate and the rated minimum discharge flow rate. This approach ensures that the device is tested effectively across its operational range.

By considering both the maximum and minimum flow rates, this method facilitates a comprehensive evaluation of the device's performance under varying conditions. Testing down to this calculated value helps to ensure that the device operates efficiently, accurately, and reliably, providing critical data for calibration and validation purposes.

This testing methodology aligns with best practices in measurement verification, ensuring that devices perform as intended across their full spectrum of capabilities. Testing only to the minimum discharge flow rate, a set percentage of the maximum rated flow rate, or all operating ranges without focusing on this specific calculation would not provide the equally encompassing verification needed for performance assessment.