The correct installation method is crucial for ensuring measurement accuracy, extending service life, and ensuring system safety when installing a gear flowmeter. The following are the main precautions when installing a gear flowmeter:
1. Installation direction and position
Vertical or horizontal installation: Most gear flow meters can be installed horizontally or vertically, but must follow the manufacturer's instructions. Some models (especially elliptical gear flow meters) recommend horizontal installation to ensure uniform force distribution and good lubrication of the gear bearings.
Correct flow direction: The flowmeter housing is usually marked with a flow arrow, and it is necessary to ensure that the fluid flow direction is consistent with the direction of the arrow. Reverse installation may damage the flow meter or result in inability to measure.
Avoid vibration: It should be installed in a location away from strong mechanical vibration sources, as vibration can affect the smooth rotation of gears, leading to measurement errors or mechanical wear.
Easy to maintain: The installation location should leave sufficient space for future inspection, maintenance, calibration, or disassembly.
2. Pipeline preparation and connection
Pipeline cleaning: Before installation, the upstream and downstream pipelines must be cleaned to remove any impurities such as welding slag, rust, dust, etc. These impurities can enter the flowmeter, causing gear jamming, scratches, or accelerated wear.
Coaxial alignment: The flowmeter should be installed coaxially with the pipeline to avoid additional stress caused by pipeline misalignment, which may result in seal leakage or internal structural deformation.
Flange connection: Use matching flanges and sealing gaskets (materials compatible with the fluid), evenly tighten bolts diagonally to prevent leakage and damage to the flowmeter.
Avoid stress: The thermal expansion, contraction or mechanical stress of the pipeline should not directly act on the flowmeter body. Suggest using flexible connections or ensuring proper pipe support.
3. Filtering and Protection
Installation of filters: It is strongly recommended to install a Y-shaped filter or basket filter upstream of the flowmeter. The mesh size (aperture) of the filter should be selected according to the requirements of the flowmeter (usually 20-40 mesh) to effectively intercept particulate matter, protect precision gears and measurement chambers.
Regularly clean the filter: It is necessary to regularly inspect and clean the filter to prevent blockage that may cause excessive pressure difference, affect flow rate, or even damage the flow meter.
4. Valve configuration
Downstream installation of globe valve: Install a globe valve or regulating valve downstream (outlet side) of the flow meter to control flow and shut down the system.
Avoid upstream throttling: Do not install a throttling valve directly upstream of the flowmeter, as this can cause turbulence and pressure fluctuations, affecting measurement accuracy.
Bypass pipeline (optional): For systems that require uninterrupted operation or regular calibration, installing a bypass pipeline can be considered, but caution should be exercised when switching between the main and bypass circuits.
5. Separation of gas and liquid
Avoid gas mixing: Gear flow meters are designed for measuring liquids. If the liquid contains bubbles or steam (gas-liquid two-phase flow), it will cause:
The measurement result is significantly overestimated (gas is included in the volume).
Gear "idles", causing cavitation and damaging the surface of the gear.
Exhaust measures: Ensure that the pipeline system can effectively exhaust. An exhaust valve can be installed at a high point upstream of the flow meter, or the flow meter can be slightly lower than the pipeline during installation to facilitate gas discharge. For liquids that are prone to vaporization, sufficient inlet pressure (net positive suction head NPSH) must be ensured.
6. Electrical connection (for models with signal output)
Follow the specifications: Connect the power line and signal line (such as 4-20mA, pulse, RS485, etc.) according to the instructions.
Shielding and grounding: Use shielded cables and ground them correctly to prevent electromagnetic interference from affecting signal transmission.
Explosion proof requirements: In flammable and explosive environments, flow meters that meet explosion-proof standards must be selected and installed and wired strictly in accordance with explosion-proof specifications.
7. Pre run inspection
Confirm installation: Check again if the flow direction, connections, filters, valves, etc. are correct.
Slow pressure rise: When starting the system, the valve should be slowly opened to gradually fill the pipeline and flow meter with liquid and increase the pressure, to avoid water hammer or pressure impact damaging the flow meter.
Exhaust: Open the exhaust valve when starting, exhaust all the air, and then close it.
Summary:
The core principles for installing gear flow meters are: ensuring fluid cleanliness, correct flow direction, stress free installation, avoiding gas mixing, and equipped with necessary protective measures (such as filters). Strictly following the installation manual provided by the manufacturer is the key to ensuring successful installation and reliable operation.