Company Profile

Mass Flow Sensors and Air Mass Meters: Hot-Wire Technology for Engine Air Intakes

Quick Answer: Silver Automation Instruments supplies hot-wire mass flow sensors and air mass meters for engine air intake measurement. The TMF100 inline series covers 0.5 to 5000 kg/h with 4-20 mA HART output. For larger ducts, the TMF200 insertion type reduces cost. Send your pipe size, flow range, gas temperature, and pressure for a fixed quote.

How Hot-Wire Air Mass Meters Work in Engine Air Intakes

Hot-wire air mass meters use a heated sensing element placed directly in the air stream. The moving air cools the element. More mass flow removes more heat. The electronics increase heating current to keep the element temperature constant. This current is proportional to mass flow. Engineers prefer this method because it gives a direct mass flow signal without separate pressure and temperature compensation.

Common Applications in Engine and Air Intake Work

We see these meters on diesel engine test benches in Vietnam and Thailand. They measure combustion air flow before the turbocharger or after the air filter. Natural gas genset packagers in Nigeria use them to monitor fuel air mixture feed. In Indonesia, a mining contractor uses an air mass meter to check intake restriction on haul truck engines. Other applications include air compressor test rigs, fuel cell air supply lines, and biogas engine intake monitoring.

Key Parameters for Specifying an Air Mass Meter

Specify the pipe size. Common sizes are DN15, DN25, DN50, DN80, DN100, and DN150. State the full scale flow in kg/h or Nm3/h. Typical ranges for air intake are 0 to 50 kg/h, 0 to 500 kg/h, or 0 to 5000 kg/h. For inline DN15 to DN50 air lines, the Silver Instruments TMF100 series covers these ranges. For larger ducts DN80 to DN200, the TMF200 insertion probe style reduces cost. Temperature matters. Standard sensors handle -20 to 150 °C. Pressure rating is usually 16 bar for engine intake lines. Accuracy is ±1.5 percent of full scale for low flow, and ±0.5 percent of reading is available for test bench use. Output options include 4-20 mA HART, pulse, or RS485 Modbus. For hazardous areas, we supply ATEX Zone 1 versions.

Why Hot-Wire Technology Works for Intake Air Measurement

Hot-wire sensors respond fast. A step change in air flow is detected within 500 ms on most models. This helps during engine transient tests. The sensors also measure low flow better than differential pressure or vortex meters. A vortex meter may lose signal below 3 m/s in a DN100 pipe. A hot-wire air mass meter still reads below 0.5 m/s. Because the signal is mass flow, you do not need a separate flow computer for temperature and pressure correction. Most engineers skip the extra wiring and just use a single 4-20 mA loop.

Installation and Calibration Notes

Mount the sensor in a straight pipe section. Upstream straight pipe should be 10 times the pipe diameter. Downstream needs 5 times the pipe diameter. If this is not possible, we add a flow conditioner plate inside the meter body. Keep the sensor away from oil mist, water droplets, and heavy dust. Many engine air intake lines carry oil vapor from crankcase ventilation. That coats the sensing element over time. We offer a self-cleaning option for such cases. Calibration uses a reference air flow bench traceable to national standards. We ship every meter with a calibration certificate.

Pricing, Lead Time, and How to Get a Quote

Price depends on flow range, pipe size, output protocol, and whether you need ATEX certification. A standard inline DN50 TMF100 hot-wire air mass meter with 4-20 mA HART starts at moderate cost for a single piece. Smaller OEM orders get volume pricing. Lead time is usually 2 to 3 weeks for standard ranges. ATEX Zone 1 versions may take 4 weeks. In practice, the fastest way is to send us four data points: gas type, flow range, pipe