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Airflow Meters and Elements: Professional Airflow Velocity Profilers for Building Audits

Quick Answer: Silver Instruments supplies airflow meters and airflow elements for building audits in Southeast Asia, Australia, Latin America, Africa, and the Middle East. Our thermal mass flow meters and pressure transmitters measure duct air velocity, temperature, and static pressure. You get repeatable data for HVAC energy studies and ventilation verification.

Building audits need more than a vane anemometer. A commercial building in Singapore or Sydney has many AHUs. Each AHU has a duct run. The airflow data must be measured at the right points. Silver Instruments provides insertion thermal mass flow meters and pressure transmitters for this job.

Why Building Auditors Use Velocity Profilers

Airflow velocity profilers map the velocity distribution across a duct cross section. ASHRAE 111 describes the traverse method. A single point reading is not enough. The velocity profile changes after bends, dampers, and filters. A profiler with multiple sensor points reduces that error.

Here is the thing. Most building audits cover 10 to 40 AHUs. The technician moves from floor to floor. The instrument must be light. The output should go to a phone or a BMS. Silver Instruments thermal mass flow meters give a 4-20 mA HART signal. That works with most portable data loggers.

Thermal Mass Flow Meters for Low Air Velocities

Thermal mass flow meters measure the cooling effect of air across a heated sensor. They work well at low velocity. A vane anemometer struggles below 0.5 m/s. Our thermal mass insertion probe meters measure from 0.1 m/s to 30 m/s. Accuracy is 1.5 percent of reading plus 0.3 percent full scale. The temperature range is -20 °C to 100 °C.

We have seen this on customer sites many times. A consultant measures 1.2 m/s at one point and then 0.8 m/s at another. The difference is not the air handler. It is the sensor position. Use a profiler with defined insertion depths. Silver Instruments supplies insertion lengths from 100 mm to 900 mm for duct sizes DN100 to DN2000.

Pressure Transmitters for Duct Static Pressure

Airflow is only half the picture. Fan performance depends on static pressure. Silver Instruments pressure transmitters cover 0 to 10 kPa, 0 to 50 kPa, and 0 to 100 kPa ranges. Accuracy is 0.1 percent full scale. The output is 4-20 mA with HART. These are compact DIN rail or field mount units. They run on 24 V DC.

A building audit in Manila used our pressure transmitter on a chilled water AHU. The static pressure was 45 Pa below design. That explained the low airflow complaints on the 14th floor. The auditor fixed the setpoint and verified the airflow with a thermal mass meter.

Airflow Elements and Probe Arrays

Some audits need fixed elements rather than portable meters. Silver Instruments can supply averaging pitot tubes, insertion thermal probes, and duct probes. Averaging pitot tubes measure differential pressure. That signal goes to a DP transmitter. The flow calculation follows Bernoulli. This is a lower cost option for large ducts above DN400.

Because building audits often include both portable and permanent checks, we recommend a kit. A thermal mass flow meter for traverse measurement. A pressure transmitter for static pressure. A paperless recorder to log data. Silver Instruments offers all three items from one supplier.

Recommended Setup for a Building Audit Kit

Here is a practical setup. Use a Silver Instruments thermal mass flow meter with an insertion probe. Set the output to 4-20 mA HART. Connect it to a portable data logger or BMS input. Measure velocity at 12 to 20 points per duct. Log temperature at the same time. Record static pressure with a separate pressure transmitter. The data set gives you airflow, temperature, and pressure in o