What are the structural principles and classifications of flow meter amplifiers and air flow meters?

『Flowmeter amplifier』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)

The core solution for EH flowmeter pre amplification plate failure is to first locate the problem through signal detection and visual inspection, and then choose to repair or replace the module according to the degree of damage. 1. Fault diagnosis steps • Signal detection: Use a multimeter to measure the input voltage (usually ± 12V or ± 15V), and the output signal should be within the range of 4-20mA or 0-10V. If there is no change in the signal or the trace changes beyond the limit, it indicates that the amplification circuit is abnormal. Appearance inspection: Observe the circuit board for physical damage such as capacitor bulges, burnt resistors, and chip pin desoldering, with a focus on checking whether the wiring terminals are loose or corroded. • Replacement method verification: Connect the preamplifier board to a normal working flowmeter of the same model. If the fault is reproduced, the board problem can be confirmed.

2. Common causes and solutions | Fault phenomena | Possible causes | Solutions | | ------------------------------------------------------------------------------------------------------------------------------------------------| Detect the bias voltage of the amplifier, replace the faulty chip | | Zero drift | Resistance aging or temperature drift exceeding the standard | Adjust the zero potentiometer or replace the high-precision low-temperature drift resistor (± 0.1%) | | Communication interruption (with HART) Protocol) | Communication module failure | Check the HART modem (such as DS8500) and peripheral circuits | 3 Maintenance precautions: Before operation, cut off the power source and discharge static electricity to avoid high-voltage breakdown of CMOS components. When replacing comp

onents, industrial grade models (operating temperature -40 ℃~85 ℃) should be selected, as ordinary commercial chips may cause a decrease in stability. • Calibration is required after repair: Input a known current value through a standard signal source, adjust the gain and zero potentiometer on the board to an output error of ≤± 0.5%

4. Replacement recommendation: If there is damage to the multi-layer PCB circuit or the main control chip (such as ARM Cortex-M series), it is recommended to directly replace the preamplifier module. The original EH board model is usually labeled as "EXC/AMP Board", and alternative models must ensure that the signal protocol and interface definitions are completely matched.

2. What are the structural principles and classifications of air flow meters?

The working principle of a flow plate air flow meter (moving plate) is the interaction between the airflow torque M and the spring force N. Therefore, the flow plate works synchronously with the throttle valve. M> At N oclock, the board is open, there is more air and more fuel injection; 2. Working principle of hot wire air flow meter: Hot wire air flow sensors are mostly analog voltage signal sensors. When the engine is running and air flows through, heat is carried away. The resistance value of the hot wire RH decreases (PTC), and the resistance value of the cold wire RC increases (NTC), causing the bridge to lose balance and increase the bridge voltage. The amplifier then increases the compensation current IH flowing through the hot wire RH, restoring the normal temperature difference of the cold wire (100 degrees Fan laughed heartily). The increase of current IH will cause an increase in the voltage drop of RA. By measur

『SILVER Official Website SERVICE』