The entire set of electromagnetic flowmeters has been calibrated and calibrated on the flow calibration device of the manufacturer. It is generally possible to put the electromagnetic flowmeter into operation without any adjustment as long as the matching numbers of sensor and converter and the meter coefficient are correct. Twisted the entire set of instruments that were adjusted. As with conventional instruments, after the electromagnetic flowmeter is installed and connected, it is necessary to check whether the following installation and wiring are correct and whether the instrument can work normally before it is put into operation. It must be emphasized here that for some units that lack experience, the instrument installation and operation personnel should carefully read the relevant technical instructions in the relevant electromagnetic flowmeter installation and operation instructions, and should be good at analyzing and thinking about the problems encountered in the initial operation. Before the instrument is put into operation, the sensor must be filled with the actual measuring medium, and after the power is turned on, the zero point is adjusted in the static state. After operation, check the zero point according to the medium and the conditions of use. Check the zero point regularly, especially for the easy-to-precipitate, easily polluted electrode and non-clean medium containing solids. In the initial stage of operation, you should check more to obtain experience and determine the normal inspection cycle. For conditional users, several basic parameters of the sensor should be measured and recorded before the instrument is put into operation. 1 Insulation resistance of the electrode (in case of sensor empty tube, insulation resistance of the two resistors to the instrument case or ground); 2 Insulation resistance of the excitation coil (insulation resistance of the excitation coil to the instrument housing or ground); 3 The cold resistance value of the excitation coil (that is, the copper resistance value of the enameled wire of the excitation coil); 4 Electrode contact resistance The sensor is filled with liquid. Measure the resistance between the electrode and ground. The contact resistance of the two electrodes should be approximately the same. When the primary device is too large to be installed on the manufacturer's test device, or if the test device flow is not sufficient, another larger flow test device can be used. If this is not possible, the user's container or reservoir can be used for on-site calibration, or it can be compared with another reference flow meter in the system. The total uncertainty should be determined according to the provisions in Chapter 10. The methods based on magnetic induction measurements and calculations of primary device signals based on physical dimensions, often referred to as "dry calibration," are outside the scope of this standard. 9.2 Nominal calibration conditions The nominal calibration conditions are those that should be available for calibration. These nominal calibration conditions should be specified by the manufacturer. For the purpose of comparison. The flowmeter shall be tested under the environmental conditions and flow conditions specified in GB/T18659. If the flowmeters have reached thermal equilibrium, it is generally conceivable that their influence on the metering characteristics of the flowmeter is negligible when the influences remain within the manufacturer's specified operating limits. This data is helpful in analyzing the cause of a sensor malfunction after a period of operation. For example, when the contact resistance of two electrodes changes, it indicates that the electrode is likely to be contaminated; the contact resistance becomes larger, the contaminants may be insulating deposits; the contact resistance becomes smaller, and the contaminants may be conductive deposits. Object; two-electrode contact resistance is not symmetrical, indicating that the degree of contamination of the two electrodes is different; the lowering of the insulation resistance of the electrode and the excitation coil indicates the degree of moisture in the sensor; when the insulation resistance drops to a certain extent, it will affect the normal operation of the instrument. The cold resistance value of the excitation coil is a parameter that guarantees the normality of the excitation coil. Activated Alumina,Activated Alumina Balls,Alumina Desiccant,Alumina Adsorbent Ningbo Cijie Chemical Equipment Co., Ltd. , https://www.shengjie-tower.com
The calibration factor should be determined by wet calibration of the water on the test device under reference (nominal calibration) conditions (see 9.2). This condition for calibration should allow the measurement to be traced back to a national or international reference, so the calibration is for known uncertainties. For example, GB/T17612 and ISO8316 give applicable calibration methods. GB/T 18659 also gives an assessment method for electromagnetic flowmeters.