Analysis of some minor faults of boiler steam flowmeter
1. The field instrument frequency changes a lot, exclusion method:
A/ First check whether the pipe section meets the requirements. The gas can be relaxed to ensure that the 5D straight pipe section after the first 10D is OK. The liquid straight pipe section does not affect the size of the straight pipe section enough. The straight pipe section is not recommended to change the installation position.
B/ electromagnetic interference may be the scene, methods to strengthen the filter function, the sensitivity down, through the dial switch to achieve.
C/site flow rate is too small, lower than the lower limit of the instrument, for example, 300-gauge plug-in test gas, the lower limit is 1500m/h, but the site indicates 500 cubic meters of instantaneous flow, because the meter is at the lower limit, the value does not change linearly. Can explain or increase traffic to customers.
A similar situation can occur with D/Measurement of pulsatile flow in liquids.
2. There is 50HZ interference on site, which is generally not covered by the outer edge of the shielded wire. Exclusion method The instrument is connected to the outer edge of the shield and the system is not connected to the outer edge of the shielded wire.
3. No signal on site
A steam flowmeter cut off no excessive flow, to modify the parameter adjustment.
The B/ meter is powered off and the test power is removed.
The C/flow rate is low and the trigger signal point D4-20mA is not set.
4. The actual flow increases, but the meter display decreases. It is definitely the cause of the working condition. It can help the customer to find the problem and the meter can be set without problems.
5. The actual flow rate decreases, the instrument display increases, most of which is vibration or the gasket is not at the center point of the pipe during installation, allowing the customer to reinstall the meter.
6. The meter display in the same condition is inconsistent with a large difference.
A/The customer's experience is wrong, or there are differences in working conditions, such as problems with the direction of the pipeline, problems with straight sections, and vibration problems.
B/Parameters Customer Modified
C/flow is too small, the lower limit is not linear
D/ stability compensation table, pressure temperature failure
7.4-20mA output meter, display and system display are inconsistent
The unit of A/parameter setting is inconsistent or the range is not consistent
The B/4-20mA output cable is too long (over 1000 meters) to lose much
8. The flow rate displayed by the meter is very different from the actual one. Most of the reasons are due to the parameter setting unit.
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