Atlas Copco QCM2-T-34050 / QCM2T34050 – Thermal Mass Flow Meter for Compressed Air Systems

The Atlas Copco QCM2-T-34050, also known as QCM2T34050, is a precision thermal mass flow meter designed specifically for compressed air and inert gas applications. This instrument utilizes the thermal dispersion principle to directly measure mass flow without requiring separate pressure or temperature compensation. The QCM2-T-34050 is suitable for a variety of industrial uses, including compressor performance monitoring, leak detection, and consumption auditing.

Principle of Operation

The QCM2-T-34050 operates by heating a sensing element and measuring the cooling effect of the flowing gas. As gas passes over the heated sensor, it carries away heat proportionally to the mass flow rate. Two temperature sensors measure the temperature difference, which is converted to a flow signal. This method provides direct mass flow measurement with high accuracy and fast response, independent of changes in pressure and temperature over a wide range.

Technical Specifications

The QCM2-T-34050 flow meter covers a flow range from low velocities to high flow rates typical of industrial compressed air systems. It is available with various insertion lengths and process connections to fit different pipe sizes. The accuracy is typically ±2% of reading plus zero drift, with repeatability within ±0.5%. The instrument outputs a 4-20 mA analog signal proportional to flow, and it includes a digital display for local readout. The operating temperature range is -10°C to 70°C, and the maximum working pressure can be up to 16 bar.

Installation and Mounting

Proper installation is critical for accurate flow measurement. The QCM2-T-34050 should be mounted in a straight pipe section with adequate upstream and downstream straight lengths to ensure fully developed flow. The insertion probe must be aligned with the flow direction and inserted to the correct depth based on pipe diameter. Atlas Copco provides mounting accessories including welding bosses, ball valves, and insertion tools that facilitate hot-tap installation without interrupting service. The electronics housing is rated IP65 for protection against dust and water jets.

Applications in Compressed Air Systems

The primary application of the QCM2-T-34050 is monitoring compressed air flow in distribution networks and individual equipment. It is used to measure total plant air consumption, identify leaks, and optimize compressor operation. In manufacturing environments, the flow meter helps allocate energy costs to different production departments by quantifying air usage. It is also employed in cleanroom facilities and pharmaceutical production where air quality and flow consistency are critical.

Integration with Control Systems

The analog output of the QCM2-T-34050 can be connected to a programmable logic controller (PLC), building management system, or chart recorder. The flow meter is also equipped with a pulse output for totalized flow, enabling energy consumption monitoring over time. Optionally, the meter can be supplied with a digital communication interface such as Modbus RTU for direct connection to automation networks. This integration allows real-time monitoring and trend analysis, supporting proactive maintenance and energy management decisions.

Calibration and Maintenance

The QCM2-T-34050 is factory calibrated with compressed air at standard conditions, and it retains calibration over long periods. However, in applications with dirty or oily compressed air, the sensor may become coated over time, affecting accuracy. Periodic cleaning with a soft brush and suitable solvent is recommended. The flow meter does not have moving parts, reducing maintenance requirements. Annual recalibration at an accredited laboratory is recommended for critical applications to maintain traceability.

Benefits of Thermal Mass Flow Technology

Compared to differential pressure or vortex flow meters, the thermal mass flow meter offers advantages such as no pressure drop, wide turndown ratio, and direct mass flow reading. The QCM2-T-34050 is immune to changes in gas composition within reasonable limits, and it provides fast response to flow fluctuations. These benefits make it ideal for variable-demand systems where accurate measurement at low flow rates is essential for detecting leaks or standby consumption.

Configuration and Setup

Configuring the QCM2-T-34050 involves setting the pipe diameter, flow range, output scaling, and optional alarm setpoints using the push-button interface. The display shows instantaneous flow, totalized flow, and diagnostic information. The setup menu also allows selection of engineering units such as m³/h, scfm, or Nm³/h. For multiple pipe sizes, the meter can be reconfigured without hardware changes, providing flexibility for temporary measurements.

Troubleshooting Common Issues

Common issues with the QCM2-T-34050 include erratic readings due to pulsating flow, zero drift from thermal offset, and signal instability from electrical noise. Users should verify that the pipe is full and free of liquid droplets, as moisture can affect thermal transfer. Checking the sensor cleanliness and ensuring proper grounding can resolve many problems. The error codes displayed on the unit guide technicians toward specific corrective actions, minimizing downtime.

Conclusion

The Atlas Copco QCM2-T-34050 (QCM2T34050) mass flow meter is a robust and accurate instrument for measuring compressed air flow. Its thermal dispersion technology provides reliable, maintenance-free operation, and its versatility makes it suitable for both fixed and portable applications. By installing this flow meter, facilities can gain valuable insights into air consumption, reduce energy waste, and improve the efficiency of their compressed air systems.