Mass Flow Controllers

Proportion-Air manufactures complete closed-loop electronic mass flow controllers that have quick response and the ability to control flow rates from 2 SCFH to 250 SCFM.

These mass flow controllers are industrial quality and can be mounted in any orientation with the ability to withstand intense vibrations while continuing to control flow. Our flow control assemblies are subject to a 10:1 turndown ratio (inquire about 20:1), meaning that we control flow at 10% to 100% of the range with ±0.25% repeatability. The gases we can control include air, argon, carbon dioxide, helium (not bubble tight), nitrous oxide, nitrogen and oxygen. Our mass flow controllers offer <10ms response time.

The building block for all of our mass flow controllers is the F-series mass flow transducer. The F-series uses high speed differential pressure technology to produce an electrical signal proportional to the mass flow of air or gas. This high speed flow signal is able to be used by a wide variety of Proportion-Air mass flow control valves to close the loop directly around air flow. Based on your required flow rate, the F-series mass flow transducer is matched to the appropriate flow control valve and then calibrated specifically to your exact flow range.

Each electronic flow control valve constantly compares your command signal to the transducer signal of the F-Series flow transducer. The control valve then opens or closes (almost instantaneously) to maintain the commanded flow rate.

Have any questions? Visit our FAQs below to look for your question.

Three Flow Control Models

with subtle differences and important implications
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FR

PRESSURE REGULATED
Requires a known and fixed regulated supply pressure to maintain calibration

FP

PRESSURE COMPENSATED
Compensates for fluctuations in inlet pressure (up to 50%) to maintain calibration

FA

ATMOSPHERIC
Requires output port open to atmosphere. Most commonly used in cylinder speed control.

Frequently Asked Questions

  • Integration involves connecting the controller to your system’s gas supply and control system, ensuring compatibility with electrical interfaces and communication protocols. We provide comprehensive documentation and technical support to assist with integration.

  • You should zero your mass flow controller before first use and periodically after that. Manufacturers determine the best method to zero their instrument based on the technology used to measure flow. Common methods include pressurizing the system without flow or then initializing the zero process, or setting a set flow, 10% for example, and adjusting the calibration for the correct reading. For Proportion-Air devices, apply 10% flow to the unit and adjust the zero for 10% signal output. If you change gases, a recalibration is necessary due to a change in the gas properties.

  • Technical support and repair are available directly from Proportion-Air. You can contact our Applications Team for troubleshooting assistance or send a part under an RMA (return material authorization) for repair. Installation, maintenance and operation manuals are available online on each part’s page.

  • The calibration interval is determined by the user, typically once a year or every two years for clean gas applications. Consider the following questions:

    • How critical is the accuracy of the measurement?
    • What is the maximum acceptable deviation?
    • Can the user check the deviation with a reference?
    • If you change gases, a recalibration is necessary due to a change in the gas properties.

  • Here are some steps you can take when using an MFC:

    1. Connect the piping.
    2. Conduct a leak check.
    3. Make electrical connections, such as for power supply and set voltage.
    4. Turn on the power supply and check for deviations from the zero point.

    Please check out the individual installation guides for each product for additional information.

  • Basic troubleshooting includes: checking power connections, verifying proper operation of any I/O modules used, inspecting for leaks, ensuring proper gas supply, and verify calibration. If issues persist, refer to the troubleshooting section of the user manual or contact our Applications Team for assistance.

  • They can control flow rates with a lowest maximum range of 40 SCFH (from literature) to 250 SCFM. Turndown from range max is 10:1.

  • Mass flow controllers, by definition, compensate for supply pressure. The Proportion-Air FP model compensates for fluctuations in inlet pressure up to 50% to maintain calibration.

  • The controller generates an error signal which is the difference between the commanded flow and actual flow. The electronics actuates the valve(s) of the controller to minimize the error signal and maintain flow at the setpoint.

  • Selection depends on factors like the type of gas, required flow range, accuracy needs, operating environment, and compatibility with other system components. Please contact our Applications Team for assistance.