Electromagnetic
flowmeter is used to measure the liquid medium in the industrial production flow of important instrument types, we know that in the process of the use of any device, with the passage of time will produce components ageing and measurement precision of drop, if not timely processing, will produce more severe impact, therefore, the precision of electromagnetic flowmeter verification to ensure its accuracy, and accumulation of original than data and subsequent validation check is necessary.
How to use simple and easy way to verify the accuracy of instrument, today, embellish instrument technology technicians will recommend to you in a simple and practical verification method, training is to use the clear water reserviors volume and checking equipment validation method.
Let's learn about the specific operation process and main points of this method.
Using visual method and the instrument method, using GS8 check sensor excitation coil resistance, the insulation resistance between line and ground resistance project conform to the standard of before delivery, electromagnetic
flow meter transducer zero point and output current, whether meet the accuracy requirement.
Specific detection method is: 1.
Measuring excitation coil resistance whether excitation coil turn-to-turn short circuit phenomenon (
Line resistance value between 7 and 8)
, resistance should be in 30 ~ 170.
If the resistance is the same as the factory records, argues that the coil is good, and indirect assessment of electromagnetic flowmeter sensor magnetic field strength did not change.
2.
Measuring excitation coil to ground (
Line 1 and no. 7 or 8)
Insulation resistance to determine whether the sensor be affected with damp be affected with damp, the resistance value should be greater than 20 megohm.
3.
Measuring electrode contact with the liquid resistance (
Line no. 1 and 2 and 1 and 3)
And indirect assessment of electrode, the condition of lining layer surface broadly.
Whether such as electrode surface and lining layer adherent deposit, deposit is electrical conductivity or insulation.
The resistance value between them should be between 1000 ~ 1 megohm, and line number 1 and 2 and 1 and 3 of the resistance value should be roughly symmetric.
4.
Close the valve in the line, check the electromagnetic flowmeter in full of liquid and liquid flow under the condition of the machine zero point.
Appropriate adjustments depending on the situation.
5.
Check the signal cable, excitation cable core insulation resistance, check whether the shielding layer is in good condition.
6.
Using GS8 calibration instruments, test the converter output current.
When given a zero flow, output current should be: 4.
00mA;
When a given flow rate 100%, the output current should be: 20.
00mA。
The error of the output current value should be better than 1.
5%.
7.
Test excitation current value (
The converter terminals between 7 and 8)
, the excitation current of positive and negative value should be within the prescribed scope, roughly 137 (
5%)
mA。
To assess the effect of the external environment on the electromagnetic flowmeter, mainly by using the method of visual observation operation of electromagnetic flowmeter in the presence of mutations or volatility roughly judge electromagnetic flowmeter without interference by electromagnetic waves or other stray wave or if there are air bubbles in the pipeline.
And clear water reserviors volume method is used to verify electromagnetic flowmeter metering accuracy is one of the methods for water supply enterprises often use.
* will first clear water reserviors water to a higher level, close all out of the water valve.
After waiting for clear water reserviors water stability, the use of artificial accurate measurement with high precision steel rule clear water reserviors transfeeder clear water reserviors and absorbing well water level.
To correct the error due to valve leakage, such as clear water reserviors again after a certain time interval measurement clear water reserviors and absorbing water level, and calculate the water leakage in unit time to fix water metering, reduce the error.
Records for verification of electromagnetic flowmeter cumulative flow, artificial clear water reserviors, the purpose of absorbing well liquid level measurement is to verify the accuracy of the liquid level transmitter.
Then open the water pump, open the water valve, after a certain time, close the discharge valve shut off the water pump.
Stay clear water reserviors water stability, again with clear water reserviors liquid level transmitter and used high precision steel rule of artificial accurate measurement of clear water reserviors and absorbing well water level, record again clear water reserviors and absorbing well water level, flow of electromagnetic flowmeter cumulative record to verify.
After calculate the clear water reserviors and absorbing well water level height difference ⊿ h, and clear water reserviors is calculated and actual water absorbing well, actual water quantity is equal to the height difference ⊿ h times the surface area and the amount of water in the revised.
To compute the electromagnetic flowmeter to verify the amount of water, with clear water reserviors actual water amount minus the electromagnetic flowmeter cumulants, get error between them, so as to verify the factory water electromagnetic flowmeter metering system precision.
Use clear water reserviors volume on the factory water factory electromagnetic flowmeter metering accuracy verification should be carried out in the case of clear water reserviors state completely static, thus make the data more accurate.
As a result, the comprehensive verification on the accuracy of electromagnetic flowmeter, electromagnetic flowmeter can be determined in the process of waterworks application accuracy, make sure whether authentic or replace the electromagnetic flowmeter measurement data.
In this paper by embellish instrument technology co. , LTD. Arrange release.
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