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Ultra-Low Flow Laboratory Gas Dosing with Bronkhorst Flow Controllers

Quick Answer: Bronkhorst flow controllers are common for ultra-low flow laboratory gas dosing because they cover ranges from 0.014 L/min to 10 L/min with high accuracy and repeatability. Silver Instruments offers comparable thermal mass flow controllers for the same laboratory gas dosing tasks, often at a lower price for customers in Southeast Asia, the Middle East, and Latin America. To get a quote, send your gas type, pressure, temperature, pipe size, and flow range.

Why Laboratory Gas Dosing Needs a Different Flow Controller

Most lab setups dose gas into reactors, analyzers, fuel cell test stands, or catalyst screening rigs. The flow rates sit far below normal industrial ranges. A pilot plant may run at 200 kg/h. A laboratory fixed bed reactor may need only 0.1 L/min of hydrogen. That changes the instrument selection.

In practice, most engineers skip this part and pick a general purpose flow meter. The result is unstable control at low flow. The valve opens too much. The flow signal drifts. We have seen this on customer sites many times. A thermal mass flow controller solves the problem because it measures the cooling effect of gas molecules on a heated sensor. It works well at very low mass flow rates.

Bronkhorst Flow Controller Specifications for Laboratory Use

Bronkhorst EL-FLOW series is widely used in ultra-low flow gas dosing. A typical laboratory unit may have the following specifications. Flow range 0.014 to 10 L/min for nitrogen equivalent. Accuracy 0.5 percent of reading plus 0.1 percent of full scale. Repeatability 0.2 percent of full scale. Response time 1 to 2 seconds. Pressure rating 64 bar. Wetted materials 316L stainless steel with FKM or Kalrez seals. Output signal 0 to 5 VDC or 4-20 mA. Power supply 24 VDC.

These controllers often appear in gas mixing systems, gas chromatography calibration rigs, and atmospheric reaction studies. A Bronkhorst unit is not the only option. You can specify a thermal mass flow controller with similar performance from Silver Instruments and avoid long lead times or high costs.

Silver Instruments Alternatives for Ultra-Low Flow Gas Dosing

Silver Automation Instruments supplies the TMF-025 series for laboratory gas dosing. This thermal mass flow controller covers gas flow ranges from 0.05 L/min to 25 L/min depending on the gas. Accuracy is 0.8 percent of reading plus 0.2 percent of full scale. Repeatability is better than 0.2 percent of full scale. Response time is under 2 seconds. Process connections are DN4, DN6, or 1/8 inch compression fittings.

The TMF-025 supports nitrogen, air, argon, helium, methane, carbon dioxide, oxygen, and many other gases. The analog output is 4-20 mA HART. Digital RS485 Modbus is available. Power supply is 24 VDC. Wetted parts use 316L stainless steel. Seal options include FKM and Kalrez. This unit works for most laboratory gas dosing setups that use Bronkhorst EL-FLOW controllers.

Here is the thing. The price difference matters for small laboratories and university research groups. A TMF-025 from Silver Instruments often costs 20 to 30 percent less than an equivalent Bronkhorst unit. The lead time for standard ranges is shorter for many countries in Southeast Asia and the Middle East. We stock some common nitrogen and air ranges in our warehouse.

Application Scenarios in Different Countries

A catalyst research group at a university in Thailand needed to dose 0.2 to 2 L/min of hydrogen and argon into a fixed bed reactor. They contacted Silver Instruments last year. The customer gave us the gas type, pressure, temperature, and flow range. We suggested the TMF-025 with a 0.05 to 5 L/min range for nitrogen equivalent. The output was 4-20 mA HART. The installation was completed in one day.

A gas sensor calibration laboratory in Vietnam was using Bronkhors