The Certified Tester shall maintain the accuracy of the testing equipment to be used

The Certified Tester shall maintain the accuracy of the testing equipment to be used to test backflow prevention devices. The testing equipment shall be checked for proper calibration and shall be recalibrated, as needed, in accordance with the recommendations of the manufacturer. Only properly trained individuals shall perform calibration adjustments or repair or testing equipment. Calibration standards utilized in the testing or repair of this testing equipment shall have their accuracy checked and adjusted to within allowable tolerances against standard instruments traceable to the National Institute for Standards and Technology (NIST).