Читать книгу Automation of Water Resource Recovery Facilities - Water Environment Federation - Страница 114

As with installation verifications, all instrument calibrations should be field-verified whenever possible. Most devices should be factory-calibrated; field verification will ensure that device calibrations are per factory settings. Some instruments will need to be calibrated in the field. As an example, magnetic flow meters are subject to wet calibration under controlled factory environments; however, a thorough check of magnetic flow meter parameters should be conducted on-site using built-in tools at the transmitter or specialized test devices furnished by the magnetic-flow supplier. In all instances, calibration documentation (e.g., certificates) should be produced by the contractor or system integrator and these should be witnessed and signed off on by site inspectors.