The importance of installing flow meters

Installation Precautions for Gas Turbine Flowmeters

1. Straight Pipe Section Requirements (Critical for Measurement Accuracy)

1. Sufficient straight pipe without turbulence shall be reserved at both upstream and downstream of the meter. D refers to the nominal diameter of the flowmeter:

• Upstream straight pipe: ≥10D (no valves/elbows); ≥10D for single 90° elbow; ≥20D for two vertical 90° elbows; ≥8D for fully open gate valve; ≥25D for globe valve / pressure regulating valve.

• Downstream straight pipe shall be at least 5D.

2. Only concentric tapered reducers/expanders are allowed for pipe diameter transition. Eccentric reducers are forbidden as they cause biased gas flow.

3. Keep the meter far away from strong turbulence equipment such as compressors and blowers.

2. Installation Direction & Position

1. Gas flow direction must align with the arrow marked on the meter body; reversed installation will stop the impeller and lead to zero measurement.

2. Horizontal installation is preferred. Vertical installation is only acceptable when gas flows upward from bottom to top. Vertical downward installation is strictly prohibited, as liquid and dust will accumulate and jam the impeller bearing.

3. Ensure coaxial alignment of flanges. Do not force or twist the meter to correct misalignment, which may deform the body and block the impeller.

3. Matching Pipeline Accessories

1. Install a Y-type strainer (80~100 mesh screen) on the upstream side to block welding slag, dust and solid particles from wearing the impeller and bearings; mandatory for gas with impurities.

2. For humid or low-temperature gas, install condensate pots and drain valves upstream to discharge liquid regularly. Residual liquid inside will corrode internal parts and cause inaccurate readings.

3. Adopt a three-valve set (inlet shut-off valve, outlet shut-off valve, bypass valve) to maintain pipeline gas supply during meter maintenance.

4. Pressure regulating valves and control valves shall be mounted at the front end of the straight pipe section instead of close to the flowmeter. Turbulence generated by throttling will greatly reduce measuring precision.

4. Working Medium Limitations

1. The measured gas shall be dry and clean. A gas-liquid separator is required if the medium contains massive droplets, oil or dust.

2. Operating temperature and pressure shall not exceed the rated parameters of the meter. Fit heat dissipation brackets for high-temperature working conditions, and add thermal insulation to avoid freezing under low temperature.

3. Open and close pipeline valves slowly to avoid instant high pressure and high flow impact that may deform or damage the impeller blades.

5. Wiring & Explosion-Proof Specifications

1. Use shielded dedicated cables between split sensor and display transmitter, routed in separate metal conduits. Keep cables clear of power cables for inverters and large motors to avoid electromagnetic interference.

2. Reliable single-point grounding for meter housing and cable shielding layers. Follow full explosion-proof construction standards for hazardous areas.

3. Equip explosion-proof cable glands and flexible conduits in explosive zones; cables shall be intact without exposed copper wires.

4. Maintain stable power supply to prevent abnormal signals caused by voltage fluctuation.

6. On-site Environmental Protection

1. Install rain and sun protection enclosures for outdoor meters to prevent circuit damage from rainwater infiltration.

2. Keep away from high-temperature heat sources and strong vibration equipment such as compressors. Long-term vibration will wear bearings and damage sensing probes.

3. Avoid open fire and static electricity sources for explosion-proof installation.