Brooks Instrument Blog

Thermal mass flow controllers are traditionally calibrated for a specific gas, a desired flow range, and a set of operating conditions. Over time, the use of conversion factors based on a ratio of specific heats between gases came into use as a way for users to configure a single mass flow controller for multiple gases. This method of configuring a mass flow controller for multiple gases is still common today – you’re using it if your device lets you select a gas by: rotating a knob, pressing a button on a display, or sending an RS232 command to the device.

Accuracy is the primary issue with this method of conversion. Converting flow rates between the calibration gas and another gas based on a ratio of specific heats can result in a mass flow control error of 5-6%. This error is the result of the conversion method because it ignores other property differences that exist between gases in the real world. If you’re changing the gas on your device with one of the actions above, ask the manufacturer of your mass flow controller what the accuracy of the device is for a gas other than the calibration gas.

P.S. If you’re told that such a device is linear in all the available gases and thus the mass flow accuracy doesn’t change when the gas is changed, RUN! This is not physically possible. Feel free to contact us for comparison data.

Multiflo by Brooks Instrument is a leap forward in configuring a mass flow controller for multiple gases because it converts based on gas differences in specific heats, densities, and viscosities. Multiflo-Capable mass flow controllers cut the conversion flow control error in half compared to devices that convert gases based on a specific heat ratio alone.

This video demonstrates how a Multiflo configuration is performed on a mass flow controller. We welcome your thoughts or questions in the comments below.

You can find more information on Multiflo-Capable mass flow controllers on the Brooks Instrument LinkedIn company page. Your local Brooks product expert would also be happy to help you configure a Multiflo-Capable mass flow controller for your applications using the information entered on this form.

If you’d like to read a bit more about instrumentation and process control, feel free to check out more of my contributions summarized on my Google Plus profile.

Designed for semiconductor, MOCVD, and other gas flow control applications that require a high purity all-metal flow path, the Brooks GF100 Series mass flow controllers deliver outstanding performance, reliability, and flexibility. Highlights of the GF100 series industry leading features include: ultra fast 300 millisecond settling time, MultiFlo™ gas and range programmability, optional pressure transient insensitivity (PTI), local display, extremely low wetted surface area, and corrosion resistant Hastelloy® sensor tube and valve seat.

GF120XSD is an extension to Brooks GF100 Series thermal mass flow controller family (MFC). Designed for extreme low pressure operation, the GF120XSD has been optimized for the precise delivery of high value, low pressure specialty gases. Read more…

This has been a product that we have been working on and perfecting on over the past several months and I’m extremely excited to finally formally launch the new GF40 and GF80 thermal mass flow controller and flow meter! These mass flow controllers provide outstanding performance, reliability and flexibility in many gas flow measurement and control applications. One of the best features of this new mass flow controller is the patented 4th generation MultiFlo gas and range configurability. MultiFlo programming is simple and fast – a new gas and range can be programmed under 60 seconds plus the device can be programmed without removing it from service or disconnecting the device from any process or tool control system.

The GF40/GF80 Series mass flow controllers features fast sub one second settling times and corrosion-resistant Hastalloy sensor tube for long-term stability. The superior valve technology provides minimum leak-by, maximum turndown and fast response which reduces overall gas panel cost and increases throughput. Additionally, the measurement accuracy of every device is verified using traceable primary calibration standards.

Want to learn more? Download the datasheet or contact your local sales engineer.

Yesterday, during the Chem Show in New York City, our very own Steve Kannengieszer was interviewed by Chemical Processing magazine‘s Senior Digital Editor, Traci Purdum. We’re still waiting for the video but I thought I would share some of the Q&A’s that were covered. If you are at the Chem Show, stop by and see us at booth 303! Read more…