Calibration procedures frequency

Comparative evaluation of international and national requirements both in the part of the volume and frequence of calibration procedures and examination of devices for ultrasonic and radiographic testing was accomplished. This review showed that procedures specified in national documents on testing and documents of EAL coincide very much. 

Any problems in the setup, startup, and operation of the CBMS also were recorded in the course of the field tests. These observations are important to improving the system before it goes into production. The field tests revealed three problems. The protective screens over electronics cooling air inlets and outlets on the CBMS II housing were damaged by operator activities in the vehicles and required reinforcement. The ground probe head, which protrudes outside the vehicle hull, required more power to maintain the correct temperature under colder or wetter weather conditions. Finally the automated mass and frequency calibration procedure was not reliable in the field and required modification. These problems have been corrected and are being incorporated in the LRIP units. 

Calibration procedures and test methods and frequencies need to be defined usually as part of an SOP. If you intend to transfer data from the instrument to a software package, ensure that data integrity is preserved during transfer. Don t assume that the transfer protocols on standard interfaces always work as intended. It is good practice to ensure that the data have not been truncated or distorted during transfer. 

Calibration procedures] are established and maintained to include details of equipment type, identification number, location, frequency of checks, check method, acceptance criteria, and the action to be taken when check results are unsatisfactory. Calibration records are maintained, and calibration environmental conditions are controlled. 

Ensures that the inspection, measuring, and test equipment is capable of the accuracy and precision necessary Establishes, documents, and maintains calibration procedures, including details of equipment type, identification number, location, frequency of checks, check method, acceptance criteria, and the action to be taken when results are unsatisfactory Identifies, calibrates, and adjusts all inspection, measuring, and test equipment and devices that can affect product quality at prescribed intervals or, prior to use, against certified equipment having a known valid relationship to nationally recognized standards. Where no such standards exist, the basis used for calibration is documented. 

Within most companies, the responsibility for calibrating measurement devices is delegated to a specific department. Often, this department may also be responsible for maintaining the measurement device. The specific calibration procedures depend on the type of measurement device. The frequency of calibration is normally predetermined, but earlier action may be dictated if the values from the measurement device become suspect. 

It was found that the normal method of scanning the frequency doubling laser by rotating the tipping Brewster plate in the reference cavity was insufficiently smooth over the small ranges required a satisfactory alternative was found to be to shift electronically the reference point used for locking the reference cavity. Further refinements to the lasers were unnecessary, because their performance did not limit the accuracy of the measurements. The calibration procedure was responsible for most of the uncertainty, and was the least satisfactory aspect of the experiment as we now discuss. 

In principle, a resonance frequency or difference in frequencies can be employed to perform NMR thermometry. The accuracy of temperature measurement depends on the accuracy of the thermocouple (0.2°C) in the NMR spectrometer. Generally, a precision of better than 0.2°C has been reported with these NMR thermometry measurements. Individual calibration plots may not be required when using aqueous buffers. Proper calibration procedures should be adopted with nonaqueous buffers and in the presence of organic modifiers. 

The example is illustrated by the results of Table 10.5. The Raman shift range from 400 to 2000 cm was calibrated with the 4-acetamidophenol shift standard, and the calibrated spectrum was recorded and stored on disk. Then calcium ascorbate was observed, with and without recalibration between spectra. Finally, spectra of calcium ascorbate were obtained approximately daily (each after recalibration) over a period of 2 months. The 769- and 1582 cm peaks were chosen for analysis, and their peak frequencies were determined by a center-of-gravity criterion included in the data analysis software (GRAMS 32). It is important that these qualification spectra duplicate the instrumental conditions to he used for real samples, at least as far as optical geometry, sampling mode, and calibration procedure. The objective is to provide an accurate indication of instrument performance in the intended application. 

It is relatively easy to get measurements of good precision for impedances between 1 and 10 Q at frequencies below 5 x 10 Hz. However, for lower and higher impedances, distortions may be observed. Very high impedances are found, for example, in measurements of protective coatings on metallic surfaces, and very low impedances are found in molten salts. The errors for high-impedance measurements originate from the finite potentiostat input impedance. Such resistance should be at least 100 times larger than the measured impedance if not, a calibration procedure is necessary. 

The sixth step in the design of an air monitoring survey is the development of a quality assurance and quality control plan. This plan should include specific sampling procedures, calibration procedures and frequency, sample custody, analytical procedures, data reduction, internal quality control checks, performance and system audits, completeness, and corrective action. 

The stringency and frequency with which calibration procedures should be undertaken is determined by whether an instrument is being used for nominal or accurate mass measurement. Modem instruments are very stable, and the mass scale... 

EPA protocol mixtures for calibration of analytical instruments for air pollution emission measurements are required to pass quality assurance tests carried out in accordance with well-defined guidelines as to instrument calibration procedures and frequency (Protocols 1 and 2). [11] They must also pass stability testing prior to acceptance. 

---