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Aalborg Mass Flow Meter: Precision Thermal Gas Processing Sensor Specs
Quick Answer: Aalborg thermal mass flow meters measure gas mass flow directly without separate temperature and pressure compensation. Common specs include flow ranges from 0 to 10 sccm up to 0 to 1000 slpm, accuracy of ±1 percent of full scale, and a 4 to 20 mA output. Silver Instruments supplies thermal gas flow meters with similar sensor specs for air, nitrogen, biogas, and natural gas lines.
What Specs Matter on an Aalborg Thermal Mass Flow Meter
Most engineers look at turndown ratio first. Aalborg GFM series meters often list a turndown ratio of 50 to 1. This means a meter with a 100 slpm full scale can still read 2 slpm with usable repeatability. Field technicians in Southeast Asia have seen this on nitrogen purge skids. They do not want a separate pressure transmitter and temperature sensor just to get a mass flow number.
Response time is another spec that plant operators ask about. Aalborg thermal gas flow meters typically respond within 0.5 to 1 second. That is fast enough for gas blending and leak test stations. In one food packaging plant in Vietnam, a customer replaced a variable area meter with a thermal mass flow meter because they needed a 4 to 20 mA signal for their PLC. They asked us for a meter with a 0 to 50 slpm range for nitrogen and a 1 second response. We supplied a Silver Instruments thermal gas flow meter with an accuracy of ±1 percent of full scale and a 0.5 second response time.
Key Sensor Specifications You Should Check
Aalborg mass flow meters use a capillary thermal sensor on low flow ranges. Most spec sheets list accuracy as ±1 percent of full scale from 0 to 5 VDC or 4 to 20 mA. Repeatability is often ±0.25 percent of full scale. Operating pressure can go up to 10 bar for many standard models. Wetted materials are usually 316 stainless steel with optional Viton or Kalrez seals. This combination works for air, argon, helium, methane, and natural gas.
Power supply options matter for OEM skids. Many Aalborg GFC mass flow controllers accept 12 to 15 VDC or 24 VDC. The output can be 0 to 5 VDC, 1 to 5 VDC, or 4 to 20 mA. If your control system uses HART, a thermal mass flow meter is not the first choice. Thermal meters usually do not have HART. For hazardous areas, some Aalborg models come with ATEX Zone 1 certification for gas groups IIB and IIC. Silver Instruments can supply ATEX-certified thermal mass flow meters for Zone 1 and Zone 2 installations.
Real Specs From a Customer Order in Malaysia
Last year a gas utility contractor in Malaysia asked us for a thermal mass flow meter to measure biogas flow into a flare. Pipe size was DN25. Flow range was 0 to 30 kg/h for biogas with a density close to 0.7 kg/m3. They needed a 4 to 20 mA output and a local display. They also wanted MODBUS RTU over RS485. We quoted a Silver Instruments thermal mass flow meter with a 0 to 30 slpm equivalent range after the gas density correction. The meter had a 316L sensor, PT100 temperature compensation, and an IP65 housing. The contractor installed it near a gas skid under a roof, so an IP65 enclosure was enough. Total lead time was 10 days.
This is the kind of detail that generic datasheets do not give you. Aalborg spec sheets are good, but you still need to match the sensor to the actual gas composition. Methane and carbon dioxide have different thermal conductivity values. A factory calibration for air will not be accurate on biogas. Ask the supplier to c
How to Size a Thermal Gas Flow Meter for Your Process
You need four numbers before you send an inquiry. Gas type, flow range, pipe size, and operating pressure. For example, a paint manufacturer in Southeast Asia needed to measure nitrogen at 2 bar in a DN15 line. Flow range was 0 to 20 slpm. Their local integrator quoted a Coriolis meter, but the cost was too high. We quoted a thermal mass flow meter with a 0 to 20 slpm range and a 4 to 20 mA output. The installed cost was about 60 percent lower. Because the line pressure was stable, the thermal meter worked well.
If your gas pressure changes a lot, be careful. Thermal mass flow meters use heat transfer from a heated sensor to the gas stream. Pressure changes affect the gas density and the heat transfer. In practice, a 0.5 bar change on a 2 bar line can shift the reading by a few percent. Use a pressure regulator upstream if you need tight accuracy. Most engineers skip this part and then blame the meter. We have seen this on customer sites many times.
Common Aalborg Models and Silver Instruments Alternatives
Aalborg GFM and GFC series are common in laboratories and small gas skids. They range from 0 to 10 sccm up to 0 to 1000 slpm. Their display models have a 2 line LCD with totalizer. Some models have a 9 pin D sub connector for power and signal. Silver Instruments thermal mass flow meters cover the same ranges and offer a compact insertion probe for DN15 to DN50 lines. We can also match the 9 pin D sub wiring if you are replacing an old Aalborg meter without changing the cable harness.
Government labs in the Philippines often order low flow meters for gas chromatography. They need a 0 to 10 sccm range for helium. Aalborg has a strong presence in that segment. Silver Instruments offers a capillary thermal sensor with the same 0 to 10 sccm range and a 0.5 percent accuracy on the calibration lab bench. We calibrate each meter against a NIST traceable reference. You get a calibration certificate with each unit.
FAQ
Can I use an Aalborg thermal mass flow meter for natural gas? Yes, if the meter is calibrated for natural gas or methane. Tell the supplier the gas composition. A meter calibrated for air will read wrong on natural gas.
What is the typical accuracy of a thermal mass flow meter? Most thermal mass flow meters list accuracy at ±1 percent of full scale. Some lab units reach ±0.5 percent of full scale. Repeatability is often ±0.25 percent.
Does Silver Instruments sell direct replacements for Aalborg GFM meters? Yes. We supply thermal mass flow meters with the same flow ranges, output signals, and mechanical fittings. Send us the full model code from the Aalborg label.
What output signals are available? Standard outputs are 0 to 5 VDC, 1 to 5 VDC, 4 to 20 mA, and RS485 MODBUS RTU. HART is not common on thermal mass flow meters.
Can I get a thermal gas flow meter for a DN15 pipe? Yes. We offer inline thermal mass flow meters for DN15 and insertion types for DN25 and larger. Send us your gas type, flow range, and pressure.
Send us your gas type, pressure in bar, temperature in °C, pipe size in DN, and flow range in slpm or kg/h. Our engineers will reply within 24 hours with a model and price. Tel: +86-25-68650347. Whatsapp: +86-25-52155837. WeChat: +86 15365082610.