Split type electromagnetic flowmeterInstallation guide for avoiding pitfalls: Several key steps and taboos are as follows:
1、 Key installation steps
Site selection and pipeline requirements
Avoid interference sources: Keep away from strong electrical equipment (such as motors, transformers), high-frequency equipment, and strong switching power supplies. The power supply should be independently separated.
Environmental control: Avoid high temperature heat sources, radiation sources, and environments with high humidity and strong corrosive gases. If installation is necessary, insulation ventilation or anti-corrosion ventilation measures should be installed.
Requirements for straight pipe section: The length of the straight pipe section before and after the sensor must meet the following requirements:
Upstream there is a tapered pipe: ≥ 15D (D is the pipe diameter);
Upstream has a 90 ° bend: ≥ 20D;
There are two 90 ° elbows (in the same plane) upstream: ≥ 25D;
Downstream straight pipe section: ≥ 5D.
Installation direction: When installed horizontally, the electrode axis should be horizontal to avoid bubble adhesion; When installed vertically, the fluid flows from bottom to top to prevent solid precipitation.
Sensor installation
Alignment and sealing: Use the symmetry rule to align the sensor with the pipeline, select a suitable sealing ring (such as a fluororubber O-ring), and tighten the bolts in 2-3 diagonal steps to the specified torque (e.g. DN100 flange requires 40N · m).
Electrode protection: Clean the electrode and measuring tube, place an air cushion between the two electrodes to prevent short circuits; Avoid touching the electrode surface with hard objects.
Full tube detection: Ensure that the medium flows fully in the tube, which can be achieved by raising the rear pipeline of the flowmeter or installing a siphon tube.
Converter installation
Location selection: The distance from the sensor should be ≤ 100 meters (with controllable signal attenuation), and it should be installed first in the control room or explosion-proof box, away from strong electromagnetic sources such as frequency converters and motors.
Protection level: Outdoor installation requires the use of an IP65 or higher protective box, with ambient temperature controlled between -20 ℃~+60 ℃ and relative humidity<95%.
Cable connection and shielding
Special cable: Use dual core shielded wires to connect sensors and converters, lay signal cables and power cables in separate slots, and make waterproof bends in conduit (the inlet is 10cm lower than the outlet).
Shielding treatment: The shielding layer is grounded at one end (converter side) to avoid parallel laying or twisting with the power cable.
Grounding system construction
Sensor grounding: Connect a dedicated grounding wire (cross-sectional area ≥ 4mm ²) through a grounding ring to ensure that the sensor and pipeline have the same potential.
Converter grounding: The independent grounding resistance is less than 10 Ω, and it is prohibited to share the grounding body with the motor or pipeline.
Calibration and Testing
Zero point calibration: Close the valve, use the power supply to directly power the sensor, read the electrical signal output and adjust it to zero drift<± 0.1%.
Air traffic control test: When confirming that there is no liquid in the pipeline, the output is zero to avoid lining damage and missed detection.
2、 Installation taboos and key points for avoiding pitfalls
Avoid strong electromagnetic interference
Problem: Strong electrical or high-frequency equipment can cause signal distortion.
Avoid pitfalls: Before installation, use an electromagnetic field detector to check for interference sources and maintain a distance of at least 1 meter.
Taboo to high temperature and corrosive environment
Problem: High temperature can damage the sensor lining, and corrosive gases can accelerate electrode aging.
Avoid pitfalls: Install insulation panels in high-temperature environments, use Hastelloy electrodes in corrosive environments, and install ventilation devices.
Taboo vibration and mechanical shock
Problem: Vibration can cause deformation of the measuring tube or loosening of the electrode.
Pit avoidance: Avoid installing it at the pump outlet or upstream of the valve. If necessary, install pipeline fastening devices and anti vibration pads at 2D upstream and downstream locations.
Prohibited non full pipe flow
Problem: Insufficient management can lead to low or fluctuating measurement values.
Avoiding pitfalls: Ensure that the fluid flows from bottom to top when installed vertically; Install a full pipe detection device during horizontal installation.
Taboo cable shielding failure
Problem: Poor grounding of the shielding layer can introduce interference signals.
Avoiding pitfalls: Check if the shielding layer is complete, avoid splicing multiple cable segments, and ensure that the single end is firmly grounded.
Prohibited grounding resistance exceeding the standard
Problem: Excessive grounding resistance can cause floating potential interference.
Avoiding pitfalls: Use a grounding resistance tester to verify, and if necessary, add grounding electrodes or resistance reducing agents.
Prohibited reverse installation
Problem: The flow direction of the fluid is opposite to the direction of the sensor arrow, which can cause abnormal measurement values.
Avoiding pitfalls: Before installation, check the flow direction of the pipeline and mark the flow direction arrow on the surface of the sensor.
Forbidden to rough handling
Problem: Lifting the measuring tube with a rope will damage the lining.
Avoiding pitfalls: Use specialized lifting straps to bind the sensor flange to avoid collisions or falls.
Prohibited uncleaned pipelines
Problem: Welding slag or protrusions can scratch the lining.
Avoiding pitfalls: Before installation, blow the pipeline with compressed air and check the flatness of the flange end face.
Taboo: Failure to reserve maintenance space
Problem: Insufficient space can lead to difficulties in later maintenance.
Avoiding pitfalls: Reserve at least 0.8 meters of operating space around the instrument for easy wiring, calibration, and component replacement.