Quality GE Bently Nevada & E&H Instrument factory

Generator Gas Replacement During Startup and Shutdown: Full Procedure and Safety Precautions Generator gas replacement must be carried out only after the generator has passed its air-tightness test and its insulation is qualified. The replacement can be performed while the rotor is stationary or running on the turning gear. This article walks through pre-checks, precautions, the startup and shutdown replacement processes, and routine hydrogen makeup. 1. Pre-Replacement Checks Put the turbine lube oil system and seal oil system into service. Carry out a full inspection of the hydrogen system to confirm replacement conditions are met. Before replacement, stop the circulating fan and isolate the online humidity meter and purity meter. Tools: power reel, copper wrench, copper hook (never use iron wrenches or hooks), and lamps (for baking piping and valves when using CO2). 2. Key Precautions During Replacement No hot work is allowed in the surrounding area during gas replacement. Copper wrenches and hooks must be used — iron tools are forbidden to avoid sparks. When working around the hydrogen system, the site must be well ventilated and well lit. Closely watch that the oil-hydrogen differential pressure tracks automatically and correctly; if not, adjust manually. 3. Startup Gas Replacement Step 1 — Replace air with CO2: Connect the CO2 cylinder outlet to the manifold interface. Open the generator CO2 inlet valve. Slowly open the CO2 discharge valve and let CO2 enter the generator, carefully controlling the charging rate. Maintain the generator internal gas pressure at 0.02–0.03 MPa during replacement. Repeatedly purge the dead corners, sampling valves and oil-water detector drains. When CO2 purity reaches ≥ 85%, purity is qualified and CO2 replacement is complete. Step 2 — Replace CO2 with hydrogen: Drain the CO2 from the generator. Contact the hydrogen plant operator and confirm the makeup method. Maintain the generator internal gas pressure at 0.02–0.03 MPa during replacement. Control the hydrogen charging rate to prevent a hot spot from excessive hydrogen velocity at pipe reducers, which could cause an accident. Repeatedly purge the dead corners, sampling valves and oil-water drains. When hydrogen purity reaches ≥ 96%, purity is qualified and hydrogen replacement is complete. Put the hydrogen dryer, circulating fan, purity meter, humidity meter and generator insulation device into service. 4. Shutdown Gas Replacement First replace the generator hydrogen with CO2; purity ≥ 95% is qualified. Then replace the generator CO2 with air; purity reaching 15% is qualified. The shutdown process is similar to startup — only the required purity differs at each stage. 5. Hydrogen Makeup During Operation Open the hydrogen makeup valve. Contact the hydrogen plant for makeup. Adjust the makeup pressure. When hydrogen pressure is sufficient, contact the hydrogen plant to stop makeup; after the makeup pressure drops, close the makeup valve. Control the makeup rate throughout the process. 6. Summary of Key Points PointRequirement Online metersIsolate the online purity meter and humidity meter for both startup and shutdown replacement. SafetyNo hot work at all times; ensure ventilation; use copper tools only. Differential pressureEnsure oil-hydrogen differential pressure tracks automatically; adjust promptly if not. Speed controlControl the charging and exhausting speed during replacement. PurityPurity must always meet the values specified in the operating procedures.

Deaerator Pressure and Temperature Changes: Why They Affect Dissolved Oxygen During normal operation of a turbine unit, dissolved oxygen in boiler feedwater always fluctuates whenever the deaerator pressure or temperature rises or falls. But do you really understand how dissolved oxygen changes, and why? This article explains the mechanics behind these fluctuations and how to keep dissolved oxygen within the qualified range. The Core Principle Behind Deaeration First, it is essential to understand the core of deaeration: only by heating the water to the saturation temperature that corresponds to the current pressure can the dissolved gases inside the water be released. Pressure and saturation temperature have a one-to-one correspondence. However, the change of water temperature always lags behind the change of pressure, and this lag is the root cause of dissolved oxygen fluctuation in the deaerator. Case 1: When Deaerator Pressure Suddenly Rises When the deaerator pressure rises, the water temperature does not rise in sync. At this moment, the water temperature is lower than the saturation temperature at the current pressure. Because the water has not reached its saturation temperature, deaeration performance deteriorates, and the dissolved oxygen in the water rises. Immediate effect: Water temperature lags below saturation temperature → deaeration weakens → dissolved oxygen increases. After a period of time: Once the deaerator heats the water up to the saturation temperature at the new pressure, dissolved oxygen falls again and returns to the qualified range. Case 2: When Deaerator Pressure Suddenly Drops When the deaerator pressure drops, the water temperature decreases slowly. At this moment, the water temperature is higher than the saturation temperature at the current pressure, so the water is in an “oversaturated” state. In this state, the dissolved gases in the water are more easily released, and the dissolved oxygen decreases. Immediate effect: Water temperature lags above saturation temperature → gas readily escapes → dissolved oxygen drops temporarily. After a period of time: Once the water temperature gradually falls and matches the saturation temperature of the new pressure, deaeration capacity returns to normal and dissolved oxygen slowly climbs back. Summary of Pressure Change Effects on Dissolved Oxygen Pressure ChangeWater Temperature BehaviorWater StateDissolved Oxygen Trend Pressure suddenly risesLags below saturation temperatureUnder-saturatedIncreases, then falls back to normal Pressure suddenly dropsLags above saturation temperatureOversaturatedDecreases temporarily, then climbs back Conclusion In short: when deaerator pressure rises sharply, the water temperature lags below the saturation temperature, so dissolved oxygen increases; when pressure drops sharply, the water temperature lags above the saturation temperature, gases are easily released, and dissolved oxygen temporarily decreases. Understanding this lag relationship helps operators anticipate dissolved oxygen fluctuation before it exceeds the qualified range, ensuring stable and reliable deaeration performance in boiler feedwater systems.

When installing an electromagnetic flow meter, one of the most common questions on site is how long the straight pipe sections before and after the meter should be. The flow profile inside the pipe directly affects measurement accuracy, so getting these lengths right matters. The Basic Rule: 5D Upstream and 2D Downstream As a starting reference, use an upstream straight section of at least 5D and a downstream section of at least 2D, where D is the nominal pipe diameter. For a DN100 meter, that means keeping at least 500 mm upstream and 200 mm downstream. These values are a practical layout guide, and the actual requirement depends on the fittings installed ahead of the meter. Why the Upstream Section Must Be Longer An electromagnetic flow meter calculates flow rate from the induced voltage generated as a conductive liquid passes through a magnetic field. After the liquid passes an elbow, tee, valve, or reducer, the velocity distribution is distorted and may swirl. If the meter is too close to these fittings, the flow has not stabilized when it enters the measuring tube, and the reading is affected. The upstream straight section gives the disturbed flow time to recover. Because the fluid entering the meter comes directly from the upstream side, the upstream section is normally longer than the downstream one. How Fittings Affect the Required Length FittingRecommendation Simple straight pipe (no disturbing fittings nearby)Upstream ≥5D, downstream ≥2D Single 90° elbowKeep the upstream straight length as long as possible Two consecutive elbows (especially out of plane)Lengthen the upstream section; swirl is stronger TeeIncrease the distance to give the flow room to recover Control valveBest layout: upstream pipe → flow meter → control valve, placing the valve after the meter Pump outletKeep a full upstream section, ensure the pipe runs full, and avoid air entrainment or cavitation What Counts as an Effective Straight Pipe Section A straight pipe section is not just about the pipe being physically straight. Within this length there should be no elbows, tees, valves, obvious reducers, or deeply inserted parts such as temperature sleeves or sampling tubes, and the diameter must stay consistent without sudden changes in cross-section. A pipe that measures 5D but contains a deep thermowell still disturbs the flow, so do not rely on length alone — check what is inside the pipe. When Space Is Limited In retrofit projects the piping is already built and space is tight. In that case: check the meter's manual for the specific straight-section requirement; see whether elbows, tees, or valves can be moved; check whether the meter position can be adjusted; and, if space is truly limited, select a model designed for shorter straight sections. Do not judge only by whether the meter physically fits — make sure the measurement conditions are adequate. Summary For an electromagnetic flow meter, start with upstream ≥5D and downstream ≥2D. If elbows, tees, control valves, pump outlets, or reducers are present upstream, lengthen the straight sections accordingly, and always confirm the final requirement against the specific model's manual. Check three things: what fittings are ahead of the meter, whether the straight section is truly clean, and what the manual requires. If you need help selecting the right electromagnetic flow meter or confirming installation requirements, please contact us for professional advice and a tailored quotation.

Radar level meters are widely used for non-contact level measurement in storage tanks across the chemical, water treatment, oil and gas, and food industries. They are accurate and low maintenance, yet their performance depends on one easily overlooked detail: the installation position. Many on-site problems, such as readings that fluctuate at low levels, sudden value jumps, and false echoes, can be traced back to a radar mounted too close to the tank wall. Why Installation Position Matters A radar level meter emits an electromagnetic beam toward the medium surface and calculates the level from the echo time. Because the beam has a beam angle, its coverage widens as the measuring distance increases. The beam radius is approximately r = H × tan(θ/2), where H is the distance from the antenna to the surface and θ is the beam angle. The whole beam path, from the antenna down to the low-level zone, must therefore be considered together. Reflections from the Tank Wall and Internal Structures The radar wave is reflected not only by the liquid surface but also by the tank wall, welds, ribs, pipes, and ladders, and metal surfaces reflect strongly. When the radar is too close to the wall, part of the beam hits the wall, so the returned signal contains wall and structure echoes as well as the true liquid echo, appearing as several peaks on the echo curve. With low dielectric media, foam, steam, agitation, or a moving surface, level identification becomes much harder, which is the origin of many so-called "false echoes". Why Low Levels Are More Unstable At high level the antenna is close to the surface and the beam is still concentrated. As the level falls, the propagation distance grows and the beam widens; once it reaches the wall, ribs, coils, or other internals, the echo curve changes. This explains why some tanks read steadily at high level but begin to jump below a certain point, with fluctuation increasing as the level drops further. The low-level zone must therefore be included when selecting the mounting point. Multipath Reflections Radar waves travel along more than one path inside a tank. Some signals hit the surface directly, while others reflect off the wall or internal structures several times before returning. Because the paths differ in length, they return at different times and produce multiple peaks. How Far from the Wall Should a Radar Be Mounted? Values such as 300 mm, 500 mm, or 1 m are often quoted on site, but the correct distance depends on the equipment and the tank. The main factors are: FactorWhy It Matters Beam angleA wider beam spreads more as it travels, so a wider clear space is required for the same distance. Tank heightTaller tanks have a longer measuring distance at low level, so low-level beam coverage must be checked. Frequency and antenna typeDifferent frequencies and antennas produce very different beam widths; narrow-beam models suit tight spaces. Internal structuresLadders, agitator shafts, heating coils, feed pipes, and ribs create strong interference echoes. The cleaner the main beam path, the better the echo and the more stable the reading. 80 GHz Radar for Tight Spaces 80 GHz radar offers a narrower, more focused beam. At the same distance it covers a smaller area, making it easier to avoid walls, coils, and agitators. This is why 80 GHz radar is increasingly chosen for small tanks, vessels with dense internals, and locations with limited space. Aligning the antenna so the beam travels straight down along the tank usually produces a clearer echo. Other Factors That Affect the Echo Near the feed inlet: splashing, foam, and turbulence disturb the beam; offsetting the sensor from the inlet improves stability. Near the agitator: rotating blades create periodic reflections; moving the radar away from the agitation zone gives a cleaner signal. Ladders, coils, and ribs: these metal parts reflect strongly, so keep the main beam in an open area. Long nozzles: a nozzle that is too long or narrow causes extra reflections. Checking Radar Status After Installation Start with the echo curve: check where the surface echo sits, how strong it is, whether clear interference peaks appear at fixed positions, and which echo the instrument is tracking. Summary When installing a radar level meter, leave a relatively clean propagation path for the beam. If the meter is too close to the tank wall, the wall, welds, ribs, and other metal structures enter the beam, and the extra echoes make level identification harder. This article refers mainly to non-contact radar level meters. If you need help selecting the right radar level meter, please contact us for professional advice and a tailored quotation.

Why Field Instrument Inspection Matters Field instruments operate for years in harsh environments characterized by vibration, moisture, corrosion and temperature swings. Over time these conditions lead to water ingress, leaks, loose wiring and signal drift. Effective inspection therefore looks far beyond a simple display check and combines the instrument body, piping, cabling, grounding, explosion-proof integrity and the surrounding installation environment. 1. Instrument-by-Instrument Checks Pressure and Differential-Pressure Gauges Look for water droplets, mist or moisture inside the case. Confirm the pointer is not stuck, jumping, bent or detached. Verify that the dial scale, range, unit and tag number are clear. Inspect the housing, glass and connections for damage, corrosion or leakage. Ensure the calibration label is intact and within its validity period. Transmitters Applies to pressure, differential-pressure, level, solids-level and temperature transmitters: Check the housing, terminal compartment and cable entries for water ingress or moisture. Confirm the displayed value, unit and status information are normal. Compare the local display with the control-system reading for significant deviation. Inspect the manifold, impulse connectors and drain ports for leaks. Ensure mounting brackets, sunshades and fasteners are not loose or corroded. Valve Positioners and Pneumatic Accessories Verify the positioner, feedback lever and mounting bracket are secure. Check the air-supply, output and tubing connections for leakage. Watch for valve creeping, oscillation, hysteresis or incomplete travel. Confirm the positioner opening matches the actual valve position. Inspect the filter regulator, pressure gauge and drain device. Gas Detectors and Audible/Visual Alarms Check the enclosure, junction box and mounting bracket for damage or looseness. Confirm no water, condensation or moisture has entered the device. Ensure the sensor inlet is not blocked by dust, oil or debris. Verify status indication and the absence of faults or communication errors. Confirm calibration, verification and sensor-replacement labels are current. Temperature Instruments Ensure the sensing element, transmitter and protective sleeve are secure. Check that compensating or extension cables do not touch hot surfaces. Confirm the local reading is reasonable and stable compared with the control system. Inspect the terminal box, cable and protective tube for water ingress or damage. 2. Piping, Cables and Grounding Impulse and pressure lines: verify neat routing, reliable supports, and check fittings, ferrules, welds and valves for leaks, vibration, corrosion, cracks or blockages. Manifolds and drain valves: confirm the manifold position matches the operating condition, and that equalizing, isolation and drain valves are correctly set. Capillary tubes: keep them free from foot traffic, protected from sharp edges and hot surfaces, and free of kinks or corrosion. Cables and wiring: check for neat, well-supported runs, aged or cracked jackets, loose or corroded terminals, and proper separation of intrinsically safe, signal and power cables. Grounding system: verify reliable grounding of instruments, solenoid valves and junction boxes, and confirm shield grounding matches the design intent. 3. Explosion-Proof Integrity and Labeling Confirm cable glands, plugs and accessories meet the site's explosion-proof requirements and that spare ports are sealed. Inspect flameproof enclosures for cracks, corrosion or missing fasteners. Ensure sealing rings, compression devices and threaded connections are complete. Confirm tag plates, nameplates and calibration labels are complete, clear and consistent with the equipment. 4. Environment and Installation Status Check for standing water, oil, debris or corrosive contaminants around instruments. Assess exposure to high temperature, vibration, salt spray, steam or wash-down water. Confirm instruments, brackets, protection boxes and bases are not loose, corroded or deformed. Keep maintenance access and operating space clear, and remove temporary supports or makeshift binding. 5. Inspection Records and Recommended Practices Records should describe the exact location and the observed anomaly rather than simply writing "normal" or "abnormal". Recommended example entries include: Observation Recommended Action Slight mist inside the pressure gauge; reading normal for now Monitor; plan seal replacement Moisture traces in the transmitter terminal compartment Inspect the cable gland and sealing Minor air leak at the positioner supply fitting Tighten or replace the fitting Loose impulse-line support with movement during operation Re-secure the support Control-system reading deviates from the local display Schedule a verification check Conclusion Field instrument inspection exists to detect water ingress, leakage, vibration, corrosion, loose wiring and poor installation before they escalate into failures. Inspection scopes should be adapted to the process, instrument type, operating environment and historical fault data, and progressively refined into a checklist tailored to each plant.

Condenser and Deaerator Dissolved Oxygen Exceedance: Causes and Corrective Actions Dissolved oxygen refers to the oxygen dissolved in water, measured in µg/L. During operation, if the oxygen content in condensate or feedwater exceeds the value specified in the operating procedures, it is considered dissolved oxygen exceedance. The dissolved oxygen in the condenser and deaerator must be kept within limits; once it exceeds them, adjustment should be made immediately. Hazards of Dissolved Oxygen Exceedance Oxygen causes oxidation corrosion of metal equipment such as pipes, valves, feedwater pumps, high- and low-pressure heaters, economizers and water walls, producing rust and impurities. Impurities clog filters and valves, affecting feedwater flow. Impurities deposit on heating surfaces, causing scaling, reducing heat-exchange efficiency and potentially leading to tube-wall bursting. Consumption of deoxygenation chemicals increases, raising unit operating costs. Long-term exceedance seriously threatens the safe and stable operation of the unit. Causes and Treatment: Condenser Dissolved Oxygen Exceedance Check whether outside air leaks into the condenser — inspect condenser vacuum, shaft seal pressure, and whether pumps and valves admit air. Low unit load, low condensate temperature and low ambient temperature make oxygen dissolve into water very easily. Properly increase the sealing water pressure of the condensate pump and adjust the sealing water to trickle evenly onto the condensate pump packing. Check the dissolved oxygen of the chemical makeup water; if it exceeds the limit, contact the chemical department to make adjustments. Causes and Treatment: Deaerator Dissolved Oxygen Exceedance Check whether condensate dissolved oxygen exceeds the limit (same checks as above). Check the opening of the deaerator exhaust-to-atmosphere valve; if too small, open it appropriately. Check whether high-pressure heater drain is normal; a leaking valve can cause oxygen to dissolve into the water. Check whether a large amount of cold water is being supplied to the deaerator — common at low load when boiler slag-cooling water is excessive. Check the deaerator heating steam source; if extraction steam pressure and temperature are low, the water is not heated sufficiently and oxygen is not fully released. Internal structure damage of the deaerator — blocked or fallen nozzles, internal breakage, etc. Large load fluctuation with the deaerator water level too high or too low causes exceedance and incomplete deaeration. Air leaking from the feedwater pump sampling valve — common when the sampling valve is not closed in time during feedwater pump shutdown for maintenance. Summary of Common Causes EquipmentCommon CauseCorrective Action CondenserAir in-leakage, low load / low temperature, uneven sealing waterCheck vacuum and seals, raise sealing water pressure, adjust makeup water DeaeratorSmall atmosphere exhaust opening, low load with low water temperature, leaking drainsOpen exhaust valve, raise heating steam, check drains and internals Feedwater pumpSampling valve admits air after shutdownClose the sampling valve in time Conclusion Condenser and deaerator dissolved oxygen exceedance can lead to unsafe events, so it must be adjusted immediately once detected. In daily operation, the most frequent causes of deaerator dissolved oxygen exceedance are low water temperature at low load, low ambient temperature, uneven adjustment of condenser sealing water, a small deaerator atmosphere exhaust opening, and air admitted through the feedwater pump sampling valve after shutdown. Correctly identifying the cause allows operators to restore dissolved oxygen to within the qualified range quickly and keep the unit running safely.

The Overlooked Accumulator: How a Silent Device Safeguards Turbine Systems Many operating personnel know only that an accumulator exists. Some cannot even tell where it is installed or what it actually does. So why does this device get overlooked? First, unlike pumps, valves and bearings, the accumulator has no temperature, vibration or current monitoring. Second, it simply “stands quietly” — when system pressure is normal, no one notices it is there. Third, operating procedures rarely describe it clearly, and there is little dedicated training on it. In turbine systems, however, the accumulator plays a critical role. It is mainly installed in the hydraulic control oil system (EH oil / governing oil) and the lube oil system. 1. How the Accumulator Works Inside the accumulator, an inert gas (usually nitrogen) is separated from the hydraulic oil by an elastic diaphragm, bladder or piston. Its energy cycle works in two stages: Energy storage: When system pressure rises, hydraulic oil enters the accumulator and compresses the gas. The gas volume shrinks and its pressure increases, so energy is stored in the form of compressed gas. Energy release: When system pressure drops or a large flow is momentarily required, the gas expands and pushes the hydraulic oil back into the system, supplying flow or holding pressure. This is exactly why, after an oil pump stops, the oil pressure does not drop to zero immediately but declines slowly — the accumulator is at work. During operation, if a pump suddenly fails, the accumulator buys operators precious golden time to respond. 2. Main Roles of the Accumulator FunctionDescriptionBenefit Store pressure oil & emergency supplyWhen a sudden leak or short pump failure occurs, the accumulator quickly releases pressure oil to hold oil pressure briefly, ensuring valves and actuators still act.Buys time for operational response Absorb pressure shocks & buffer pulsationPump start/stop and fast valve switching create pressure fluctuation and water-hammer shocks; the accumulator absorbs them and reduces oil pressure pulsation.Protects pipes and pressure components, cuts vibration Maintain system pressure stabilityWhen small amounts of oil are used and pressure drops slightly, the accumulator releases oil to compensate.Stabilizes working pressure, avoids frequent pump cycling and reduces energy consumption Compensate for leakageMinor internal leakage in hydraulic valves and seals slowly lowers pressure over long runs; the accumulator continuously tops up a small amount of oil.Maintains system pressure over time 3. Operation Monitoring and Inspection Monitor whether the EH oil main pipe pressure and the lube oil main pipe pressure are steady, and check for abnormal fluctuation. Inspect the accumulator appearance: leakage, vibration, abnormal noise, and frosting or oil seepage at the charging valve. Conclusion The accumulator is a quiet but indispensable guardian of turbine hydraulic and lube oil systems. Although it is easy to overlook, it stores energy for emergencies, absorbs pressure shocks, stabilizes system pressure and compensates for leakage. Regular monitoring of oil pressure stability and careful visual inspection of the accumulator are simple steps that can prevent unexpected downtime and protect the entire system.

Project Background Vortex flowmeters are a cornerstone of accurate flow measurement across the chemical, petrochemical, water treatment and power generation industries. However, even a well-engineered vortex flowmeter can deliver unreliable readings when it is exposed to adverse installation conditions, electrical interference or insufficient maintenance. This case study summarizes a structured field-troubleshooting program developed for a manufacturing client whose process control and measurement accuracy had been repeatedly disrupted by recurring vortex flowmeter faults. Key Fault Symptoms and Corrective Actions 1. Pipeline Has Flow, but the Vortex Flowmeter Produces No Output or a Blank Display Power supply not connected or voltage out of the operating range: inspect the power supply and confirm that the voltage matches the meter specification. Flow rate too low and below the meter minimum range: increase the flow rate or reselect a flowmeter with a suitable measuring range. Pipeline valve closed or not fully opened: verify and correct the valve position. Signal amplifier board failure: contact after-sales support to repair or replace the amplifier board. 2. No Flow in the Pipeline, but the Meter Still Outputs a Signal Strong electrical or high-frequency interference near the meter: relocate the installation point away from the interference source. Excessive pipeline vibration or a nearby vibration source: reinforce the pipeline or choose a new mounting location. Valve not fully closed: inspect and ensure the valve closes tightly. Amplification gain or trigger sensitivity set too high: adjust the parameters to appropriate values. 3. Unstable Flow Output Electrical interference combined with poor grounding: check the shielded signal cable and amplifier-board fasteners to guarantee solid grounding. Insufficient straight pipe length or a mismatched pipe bore: reinstall according to the manual and select a matching pipe. Pipeline vibration: reinforce the pipeline or relocate the meter. Non-concentric installation, seal gasket problems or disturbing valves upstream/downstream: reinstall the meter or inspect the valves. Fluid not filling the pipe or a gas–liquid two-phase flow: re-select a proper installation point. Foreign objects or wrappings at the meter inlet: remove the meter and clean the inlet. 4. Displayed Flow Does Not Match the Process Flow No real-time temperature/pressure compensation for gas or steam, or incorrect setpoints: add temperature and pressure elements and verify the actual operating conditions. Incorrect installation positions of the temperature and pressure elements: re-select and reinstall the measurement points. 5. Additional Faults and Remedies Sensor damage caused by mechanical impact, over-temperature, over-pressure or corrosion: replace the sensor promptly. Display failure due to poor contact or damage: reconnect or replace the display. Long-term operation without maintenance: implement a scheduled maintenance and inspection program. Quick-Reference Troubleshooting Summary Symptom Likely Root Cause Recommended Action No output with flow present Power, valve or amplifier board Check power, open valve, repair or replace the amplifier Output present without flow Interference, vibration or high gain Relocate, reinforce the pipe, adjust parameters Unstable output Grounding, straight pipe or two-phase flow Fix grounding, reinstall, clean the inlet Reading mismatch Missing compensation or wrong installation Add T/P elements, verify setpoints Results and Client Benefits By applying this systematic diagnostic checklist, the client maintenance team reduced unplanned flowmeter downtime, restored measurement accuracy and extended the service life of its vortex flowmeters. Routine inspection, periodic cleaning of the sensor and rotor surfaces, and timely replacement of worn components proved to be the most effective measures for preventing faults before they affected production. This case demonstrates that reliable vortex flowmeter performance depends not only on correct product selection but also on proper installation, grounding and a disciplined preventive maintenance schedule.

Project Background Accurate measurement of compressed air is essential for energy management, leak detection and cost control in modern production facilities. When an industrial client deployed an E+H mass flowmeter to monitor compressed air consumption, the initial readings were unstable and occasionally inaccurate because the meter had been left with factory defaults intended for liquid service. This case study documents the complete parameter configuration performed to obtain reliable gas flow measurement. Key Parameters Configured for Compressed Air 1. Measurement Unit Settings The mass flow unit (for example kg/h or t/h) and the totalizer unit were set to match the actual application so that operators could read and record consumption consistently with their energy-management system. 2. Range Settings The lower (4 mA) and upper (20 mA) limits of the analog output were configured according to the expected compressed-air flow range, ensuring that measured values are displayed accurately within the calibrated span. 3. Low Flow Cutoff (Optional) To suppress tiny flows and signal noise, a low flow cutoff of approximately 1%–5% of the full range was applied, preventing minor fluctuations from affecting measurement precision. 4. Empty Pipe Detection (EPD) Because compressed air has a very low density, empty pipe detection was switched off for gas measurement. Leaving EPD enabled can cause false alarms and measurement interruptions when the gas density is low. 5. Flow Direction Setting The measuring direction (forward or reverse) was configured according to the actual installation orientation so that the meter correctly identifies the direction of media flow. 6. Density-Related Parameters (Optional) To calculate standard volumetric flow or perform density compensation, the standard-condition air density (about 1.293 kg/m³) was entered and density compensation was enabled. 7. Damping Settings (Optional) The flow damping factor was tuned to the on-site working conditions to smooth the measurement signal and reduce output fluctuation. Configuration Summary Parameter Recommended Setting Purpose Measurement unit kg/h or t/h + totalizer unit Match application and reporting Range (4–20 mA) Lower and upper limits per expected flow Accurate span display Low flow cutoff 1%–5% of full range Remove noise and micro-flows Empty pipe detection Disabled for gas Avoid false alarms Flow direction Forward or reverse per installation Correct flow recognition Air density 1.293 kg/m³ + compensation Standard volumetric flow Damping Tuned to site conditions Smooth the signal Results and Client Benefits After the parameters were configured through the flowmeter's operating interface and companion commissioning software, the client obtained stable, accurate compressed-air measurements, improved the reliability of its energy-monitoring data and gained a clearer picture of air consumption across production lines. These settings confirm an important practice: the exact procedure may vary slightly between models, so consulting the device manual or an E+H technical support specialist ensures the optimum configuration for each application.

Customer Background The turbine-generator is the heart of a thermal power plant, and mechanical quantity instruments are the electrocardiogram that watches it beat. In the thermal instrumentation of a 600 MW-class power plant we support, the Turbine Supervisory Instrumentation (TSI) system continuously monitors shaft relative vibration, bearing absolute vibration, axial displacement, differential expansion, casing expansion, rotor eccentricity, speed / zero speed and key phasor. However, frequent false TSI alarms, drifting readings and unclear maintenance standards troubled the instrumentation team, so they worked with our engineers to rebuild a reliable measurement and maintenance system. Challenge Frequent false TSI alarms that disturbed operators and risked unit trips; Unstable or drifting signals on shaft vibration, axial displacement and expansion channels; Gap voltage moving out of the linear zone, signal loss caused by open or short circuits, and inaccurate readings from contamination, loose brackets and aging sensors; No clear standards-based procedure for installation, overhaul and acceptance of mechanical measurement loops. Solution: A Complete Measurement and Maintenance System Our solution covers the six parameter families of turbine mechanical condition monitoring - vibration, displacement, expansion, speed, eccentricity and key phasor - built on three core sensing technologies: Eddy-current sensors - the workhorse of TSI measurement. Non-contact measurement based on the eddy-current effect with a 0-10 kHz frequency range, resolution down to 0.01 mm and strong resistance to oil contamination. Typical output is -4 V to -20 V DC, with the gap voltage set at the linear midpoint (about -10 V DC for a 200 mV/um, 8 mm probe). They cover shaft vibration, axial displacement, differential expansion, eccentricity, key phasor and speed measurement. LVDT sensors - contact-type displacement sensors for large travels up to 0-80 mm with linearity within ±1% F.S., mainly used for casing expansion and part of differential expansion. TD-2 series thermal expansion sensors provide 4-20 mA retransmission plus local indication. Magnetoelectric velocity sensors - the traditional choice for bearing absolute vibration, rigidly mounted on machined bearing pedestals; modern units may use piezoelectric accelerometers with double integration. Typical 600 MW Unit TSI Configuration Monitoring ItemTypical Configuration Shaft vibration7 bearings x X/Y directions, 14 eddy-current probes Bearing absolute vibration7 magnetoelectric velocity sensors Axial displacement2-3 eddy-current probes (redundant) Differential expansion1-2 eddy-current or LVDT probes per HP/LP side Casing expansion1-2 LVDT sensors Eccentricity / key phasor1 eddy-current probe each Speed / zero speed2-3 sensors (magnetoelectric + eddy-current combination) For sensor selection, the probe coil diameter determines the measuring range: 8 mm probes cover about ±1 mm for shaft vibration, eccentricity and key phasor; 11 mm probes ±2 mm; 14 mm probes ±4 mm for medium axial displacement and differential expansion; 25 mm probes ±6 mm; and 50 mm probes ±12 mm for large expansion measurement. Fault Handling and Maintenance Highlights Following GB/T 34578-2017 and DL/T 1056-2019, we helped the plant establish daily inspection and troubleshooting mechanisms for the five most common fault families: unstable output or drift, abnormal gap voltage jumps, signal loss or constant output, inaccurate readings, and frequent false alarms. Key engineering practices include: Single-end grounding of the shielded cable at the TSI cabinet side only, with the probe side floating to eliminate ground loops; Checking probe coil resistance (about 7.5 Ω ± 0.5 Ω for typical series) to identify open or short circuits; Sealing high-frequency joints with heat-shrink tubing and keeping them insulated and floating as required by DL 5190.4-2019; Setting the zero reference with the thrust disc seated against the thrust bearing, and verifying protection set-points by simulated wear tests; Calibrating sensors every 6-12 months, keeping insulation resistance above 1 MΩ, and maintaining complete technical archives. Outcome After the retrofit, false alarms were eliminated, measured values returned to the trustworthy linear zone, and the plant gained a clear standards-based workflow covering installation, routine inspection, overhaul acceptance and protection logic testing (DL/T 1012-2006, GB/T 11348.2-2012, GB/T 6075). Shaft vibration evaluation is now performed against the A/B zones of the national standards, and every measurement loop truly acts as the sentry of long-term, safe turbine operation. For OEM supply of eddy-current probes, preprocessors, LVDT and velocity sensors, or TSI retrofit and commissioning support, contact our engineering team.