Certifications of Elastomer O-Rings for Mass Flow Controllers Explained

January 17th, 2017 No comments

Mass Flow Controllers (MFCs) are used in many applications that require different certification requirements for materials that could come into contact with anything going into the end product. For gas control in bioreactors, gas is being controlled by MFCs in a gas box, in open frame systems, or mounted on a skid. Process gasses go through the MFC and into the bioreactor to control the cell growth and cannot be contaminated by the materials in the gas supply components.certifications of o-rings in mass flow controllers

Many MFCs use elastomer sealing materials and it is important to make sure you have materials that are certified to be safe for the application. For example, our SLA Series MFCs offer USP Class VI O-rings in two different materials (Viton and EPDM – See blog on elastomer selection). So what does this even mean?

USP Class VI
USP stands for U.S. Pharmacopeia, a private (non-government) organization that ‘promotes the public health by establishing state-of-the-art standards to ensure the quality of medicines and other health care technologies’. For plastics, they have 6 different classes based on duration and application. Class VI is the most stringent and requires three tests:

  1. Systemic injection test
  2. Intracutaneous test and
  3. Implantation tests

In order to pass the Class VI standards, the product/material must exhibit a very low level of toxicity by passing all the tests requirements when tested according to ISO 10993.

The FDA requires testing of finished devices, however, the demonstration of biocompatibility of materials according to USP Class VI standards is provided as an aid to device manufacturers in their material selection process.

ADI-Free / BSE-Free / TSE-Free
Another up and coming requirement is ADI free (BSE / TSE free). This is to certify that the raw materials used in production of the elastomer contain no Animal Derived Ingredients (ADI) and are therefore Bovine Spongiform Encephalopathy (BSE) Free and Transmissible Spongiform Encephalopathy (TSE) Free with respect to source, manufacture and treatment. This assures the user that there is no path for these pathogens to contact their process or product. This is a statement from manufacturers certifying that there no substance of animal origin used to manufacture the product.

When you see ‘CFR 21 FDA 177.2600’ on MFC O-rings it means that it is on the FDA list of base elastomers that are recognized as inherently safe and classified as GRAS (Generally Recognized as Safe).

Of course, we here at Brooks Instrument are always happy to answer questions around our compliance with these standards in our products so feel free to contact us.

IP, NEMA: What does it all mean and what’s best for my wash-down application?

January 3rd, 2017 No comments

We are going to take a look at the IP and NEMA ratings and what they mean. With this information you should be able to decide what minimum level of protection you need for your application.SLAMf Mass Flow Controllers

Let’s start with the basics. What does IP and NEMA stand for? IP stands for ingress protection and NEMA stands for National Electrical Manufacturers Association. Both IP and NEMA are rating systems for equipment that might be exposed to liquids, rain, ice, corrosion and contaminates such as dust.

IP Rating System

An IP number contains two numbers (i.e. IP65) in most instances which relate to the level of protection provided by an enclosure or housing. The first number relates to protection from solids as follows: Read more…

At the Cusp of Exciting New Technology

December 19th, 2016 No comments

What do the Corvette and today’s new jet engines have in common (besides both going really fast)?

Answer: They both use carbon fiber materials in their construction to be lighter, more efficient and, of course, faster still.

Why, you might ask, is a flow measurement and control company like Brooks Instrument so interested in these materials?

Why Ceramic Matrix Composites (CMC)?
The material being manufactured for today’s jet engines is a Ceramic Matrix Composite or CMC. The making of these CMCs require multiple gas streams during the manufacturing process. Brooks Instrument thermal mass flow controllers are used on these gas process lines extensively throughout the entire procedure. The most common CMC configuration is a composite of tiny interwoven ceramic silicon carbon fiber embedded and intertwined in a silicon carbon-carbon ceramic matrix giving it “supernatural” capabilities. Specifically, the resultant material becomes extremely heat resistant, more so than its high-alloy metal predecessor. This ceramic material will not decompose up to 4900°F, doubling the heat resistance of the high-alloy metals. The CMC material is also lightweight as it is one third the density of conventional metal alloys used in jet engines. The “Matrix” gives the material its strength, outperforming its metal competitors.


GE9X Engine Cutaway

Manufacturing CMCs
As you can imagine, manufacturing a complex material like this comes with its challenges. And that’s where our latest advancement in mass flow technology delivers thousands of dollars of savings in process downtime.

Our GF40 Series and GF80 Series mass flow controllers are used for the “standard” gas streams like N2 (nitrogen), CO2 (carbon dioxide) and other purge gases. These gas lines make up most of the processing gas for manufacturing. There are, however, a couple of major process gases used that present particular complications. These gases, also, are essential to the success of the final product.

The two gases in question are BCL3 (boron trichloride) and SiCL3 (trichlorosilane) which are used as precursor material during Chemical Vapor Infiltration (CVI), an integral part of the creation of a CMC. These gases pose inherent risk during the process as they have low vapor pressures meaning they want to be a liquid most of the time. Additionally, they are difficult to manage as they react quickly with moisture in the air to create a corrosive concoction. They must be tightly monitored and controlled to avoid failure in the process. The accuracy of the thermal mass flow controllers (MFCs) used with these two gases must be carefully scrutinized requiring regular and frequent process shutdown and MFC flow verification. This can cost upwards of $10K per hour.

Here is where the Brooks solution is realized. We have a product designed to enable in-situ gas flow verification with no need to shut down the process for MFC health checks. The GF135 Series supplies continuous process flow data during the entire process using an on-board ROD (Rate of Decay) secondary flow measurement. The user can take advantage of:

  • Enhanced process gas accuracy
  • Market leading pressure transient performance, and
  • MFC health indicators such as automatic trending of sensor stability and valve performance/shutdown (leak-by)

Each GF135 is gas specific and proven on the actual gas it is set up for – no guessing or inferences here. We know it works because we brought in the gases to our lab and used them for proof positive. The GF135 saves time and money and is the only product of its kind in the industry. And it simplifies the process!


GE9X Commercial Aircraft Engine

CMCs are expensive to make so cost cutting is important and in demand in the industry. The GF135 is the solution for BCL3 and SiCL3 gases however it can also be used on other difficult to manage gases used in the process of making CMCs like NH3 (Ammonia).

So what’s next in our world of innovation? Warp Drive perhaps? Doesn’t this GE9X CMC laden jet engine manufactured by GE Aviation look like the Starship Enterprise?

Flow Totalization in Gas Usage Monitoring

October 31st, 2016 Comments off

A common application where accurate flow totalization is required is gas usage monitoring. In this application there is typically a single source of gas being shared by several different users or locations within a facility. To account for usage, or allocate costs properly, the facility needs to monitor the amount of gas consumed by each user.

Typical Installation

A typical installation for this application includes several flow meters, secondary electronics with totalizer function cabling from each device connected to a central monitoring system. The totalizer gets a flow signal from the flow meter, calculates the totalized flow and sends that value to the central monitoring system.

Gas Usage Monitoring Diagram

Typical gas usage monitoring installation

With this approach the accuracy of the totalized flow may not be optimized. There may be some additional error due to resolution of the analog to digital converters (ADC) and signal noise. The user also needs to be sure the analog signals were calibrated properly and that they match the span and time units of the flow meters. Signal filtering, signal cutoffs, sample rates and sample period can also have an impact. All of these factors could lead to improper billing or cost allocation. There is also additional hardware and cabling costs with this approach that could be avoided.

A Lower Cost Approach

An alternate approach uses digital mass flow meters, like the Brooks SLA Series, which calculate the totalized flow value internally. With this approach, no additional inaccuracy is introduced with a secondary calculation or digital to analog conversion.

Gas Usage Monitoring Diagram Using Brooks SLA Series MFCs

Gas usage monitoring installation using Brooks SLA Series Mass Flow Meters










Another advantage of this approach is that the user is able feed the totalized flow value directly to the gas monitoring system via digital communication. This eliminates the need for the totalizers and simplifies the wiring, therefore reducing the total installed cost of the system.

Validating Totalized Flow Accuracy

To confirm the totalized flow accuracy of the SLA Series mass flow meters, Brooks Instrument used a Bell-Prover (traceable flow calibration standard) and a formal totalizer verification process. With this approach we were able to demonstrate totalized flow accuracies of better than 1.2%. The chart below summarizes the data for 12 devices each run at four (4) flow rates.

Brooks Mass Flow Meter Error Rate Date







Brooks Instrument SLA Series mass flow devices are available with a variety of digital communication protocols and a range of options to satisfy even the most difficult applications including hazardous area and outdoor installations.

To learn more about our proven mass flow devices for gas usage monitoring or any other application where totalized flow is required, please contact us.

Using LabVIEW™ Software to Interface with Brooks Instrument Thermal Mass Flow Controllers

September 15th, 2016 Comments off

Brooks Instrument Model GF40 MFCs (qty 4) with Multi-drop Cables

LabVIEW™, a National Instruments software development tool, is widely used to create software applications that monitor and control a variety of sensors and control devices. It is very common to find a laboratory, university, or a pilot manufacturing plant using one of these applications to interface with mass flow devices. LabVIEW™ software can interface with a Brooks Instrument mass flow device through different forms of data acquisition. The most popular forms of data acquisition used with Brooks Instrument mass flow devices are described below.

Analog Signal Interface

The chances are good that LabVIEW™ software users have analog to digital I/O cards, and can run their MFCs utilizing the 0-5 volt or 4-20 mA analog signaling via LabVIEW™. This is recommended for anyone who may not be ready to move to direct digital control.

national instruments power supply

Power Supply by National Instruments

RS485 Digital Signal Interface

Brooks Instrument mass flow devices configured with the ‘S’ communications option provide RS485 digital communications via the 15-pin D connector. The RS485 digital signal can be passed directly to the computer running LabVIEW™ through a serial RS485 converter. The GF40, GF80 and SLA Series MFCs from Brooks Instrument can be configured with the ‘S’ communications option.

    • Brooks Instrument provides a free set of VI files for use with LabVIEW™ software via our website which can be loaded directly into the LabVIEW™ application, and provide the building blocks for creating a LabVIEW™ software control interface utilizing the S-Protocol digital command structure. Additionally, a Brooks LabVIEW™ DLL file is included so these building blocks can be referenced and used within a LabVIEW™ application program interface (API).
    • Another possibility is to use the Brooks Instrument Smart DDE (Dynamic Data Exchange) software as an alternate tool to create links between the LabVIEW™ application and the GF40, GF80 or SLA Series flow, control, and configuration parameters. Additionally, the user can leverage Windows applications (Excel, Word, Access) and programming languages ( C++, C#, Visual Basic) and SCADA programs from suppliers such as Allesco and Millennium Systems International. No knowledge of the mass flow device S-Protocol command structure is required. With Smart DDE, the user gets direct access to the required data fields. This is not a 100% turnkey solution, but reduces the amount of coding required to communicate with and control the MFC.

DeviceNet Digital Signal Interface

GF40, GF80 and SLA devices configured for DeviceNet digital communications can also be controlled via the LabVIEW™ application. Note that this requires a National Instruments DeviceNet interface card and associated drivers and software, which provide support for developing application interfaces using LabVIEW™ software for Windows and LabVIEW™ Real-Time. The following is taken from the National Instruments website:

National Instruments DeviceNet for Control interfaces are for applications that manage and control other DeviceNet devices on the network. These interfaces, offered in one-port versions for PCI and PXI, provide full master (scanner) functionality to DeviceNet networks. All NI DeviceNet interfaces include the NI-Industrial Communications for DeviceNet driver software, which features easy access to device data and streamlined explicit messaging. Use a real-time controller such as PXI and NI industrial controllers to create deterministic control applications with the NI LabVIEW Real-Time Module.

So, don’t be afraid to go digital. The digital aspect of our mass flow devices include many on-board functions that work in the background and make the device superior even if the final flow signal is sent via analog signal (0-5 Vdc or 4-20 mA).

Successfully Managing Industrial Chlorinated Processes with Metal Sealed Mass Flow Controllers

August 9th, 2016 Comments off

Chlorine (CL2)Chlorine (CL2) is a member of the halogen elements group that is highly reactive and bonds easily with hydrogen to form HCL acid. HCL attacks stainless steel aggressively – literally passivating the surface of the stainless steel, and can render a thermal mass flow controller inoperative in a brief period of time. CL2 is used frequently in many applications from making PVC pipe and treating water to plasma etching a computer chip. CL2 is a critical process element in our world. CL2 mass flow controllers typically have a significant life span reduction which can be improved using tightly managed process controls. So what needs to be controlled in a CL2 process?

1) Leak test your system
The primary contaminant component for CL2 applications is air and its entrained moisture (water) content. To avoid this process “invasion” it is imperative that the entire system be leak tight at the onset of work. The best (and cheapest) way to do this is to pressurize the line with clean, dry nitrogen (N2) to 50 PSIG. Make sure the line is not blocked in any way with shut off valves, etc. Measure the line pressure as accurately as possible and allow the piping to stand in a static mode for a 24 hour period or longer if possible. Recheck the pressure reading to verify no decay has taken place. It is best to verify leak integrity in a temperature stable environment.

2) Pump purging before every start up and after every process run
Eliminating air content in the process line before CL2 is introduced is essential to a successful startup procedure. Purging the process path after a process run will further enhance the longevity of your CL2 mass flow controllers. Cycle-purging using dry N2 is the best method to accomplish the purging process. This is accomplished by raising the N2 purge gas line pressure to 30 PSIG and then exhaust to a small backpressure of 1-3 PSIG. This backpressure will protect the process line from back flow of air. This process should be repeated at least 15 times to evacuate as much air or other moisture bearing gas from even the smallest dead space in the line. Maintaining a high vacuum state in the process line after this this cycle- purging is completed will qualify a “clean” system for CL2 service.

3) Eliminate the possibility of contamination from the N2 purge source
The N2 purge source should be certified to have less than one part per million (1 PPM) of moisture/O2 in it. This should be verified periodically with in situ testing. It is best to use a dedicated N2 purge gas line for CL2 services. Ideally, specialized gas purifiers (as used in the semiconductor industry) should be used just prior to the point of process gas use as a primary precautionary method. These purifiers are a necessity to achieve better than 100 parts per billion moisture content which is the recommended “safe” level to minimize / eliminate the production of hydrochloric acid in the process stream.

4) Use the appropriate/best mass flow controllers for CL2 service
The ideal thermal mass flow controller for CL2 gas service is the Brooks Instrument metal sealed GF80 Series or GF100 Series. Metal seals eliminate the possibility of outgassing thru elastomeric o-rings, keeping air out of the flow stream. These products have essential functional components made of Hastelloy C-22 – flow sensor, valve seat, and valve orifice. Hastelloy C-22 is inherently corrosion resistant to CL2. Additionally the GF80 Series and GF100 Series products have a 10µ inch Ra surface finish or better for particle free function. The exceptional performance of the GF series is enhanced by our MultiFlo™ technology – gas and range programmability embedded in the electronics of each device. Actual CL2 gas was used to establish an empirical CL2 gas calibration table inherent in every GF Series product. The GF80 and GF100 Series will exceed your expectations for the best accuracy and performance in your CL2 application!

Are there direct replacements for Full-View® glass tube flow meters (models 1110, 1114, 1140, 1144)?

July 25th, 2016 Comments off
Full-View Glass Tube VA Flowmeter

Full-View® 1100 Series

With the obsolescence of Full-View® models 1110, 1114, 1140 and 1144, we are often asked for a direct dimensional flow meter replacement. The GT1306 (127,150mm) and GT1307(250mm) retro-fit meters will accommodate the same fit, form and function as the existing meters. Please note you will need the following information to complete a sizing and model configuration:

  • Original sizing and flow specs
  • Overall length and center to center dimensions
  • Connection type: either NPT or Flange and the orientation of the connections
  • Elastomer compatibility

You can access more details on replacement options here.

Three Brooks Instrument products recognized in 2016 Control Readers’ Choice Awards

July 8th, 2016 Comments off

Control readers have great taste: Once again, they recognized the performance, accuracy and reliability of several Brooks products by awarding us top rankings in two categories (and third-place ranking in another) in the 2016 Control Magazine Readers’ Choice Awards.

We were recognized in three categories: Top choice for variable area flow meters and positive displacement flow meters and third place for thermal mass flow meters. That makes NINETEEN years in a row that our VA flow meters have been named 1st choice by more than 1,000 automation professionals surveyed.

Winning this award has always meant something special to us here at Brooks. It’s chosen by the end-users of our instrumentation, and they are asked to compare our performance with our competition, so when they award us top ranking it validates our hard work and our constant focus on delivering the finest technology in the industry.

Thanks to Control and a special thanks to the readers of Control Magazine for your votes!

Download the complete 2016 Readers’ Choice Awards article.

Understanding Mass Flow Controller (MFC) Accuracy

June 14th, 2016 Comments off

Accuracy EquationOne of the key factors typically considered when selecting a measurement device, such as a mass flow controller (MFC), is accuracy. Anyone who has researched Mass Flow Controller accuracy likely knows that there is a wide variety – both in how accuracy is stated and the device performance.

So how does anyone make sense of this variety of accuracy statements? Let’s start by looking at the three basic building blocks of accuracy:

  1. Calibration and Measurement Capability (commonly referred to as CMC)
  2. Repeatability, and
  3. Linearity

The first element, CMC, relates to the equipment and process used to test devices, while repeatability and linearity are related to the device itself.

In short, CMC is a measure of how closely the calibration method represents “truth” or absolute accuracy. No calibration equipment or method can perfectly reflect “truth”; therefore, the uncertainty associated with CMC is always >0. CMC captures both the inaccuracy of the components of the calibration system and the statistical variation during its use.

For more information on CMC, visit: http://www.isobudgets.com/know-cmc-uncertainty/

This represents the device’s ability to repeat a flow measurement under the same conditions in a short period of time. If an MFC was used to create a specific flow rate over and over again in rapid succession without changing conditions, the distribution of the flow measurement data points (in excess of the variation in the CMC) would indicate the repeatability of the MFC.

This element is needed because all Mass Flow Controllers are inherently nonlinear to some degree. To account for this, a curve-fit correction is applied to the devices. This is accomplished by collecting multiple data points during a calibration process and determining a curve fit equation. Linearity indicates how well the curve-fit correction worked.

Each of these building blocks contributes some amount of uncertainty to the accuracy of an MFC. The sum of those uncertainties equate to the device accuracy.

Accuracy = CMC + Linearity + Repeatability

All of these factors impact the accuracy that you see on the spec sheet for an MFC or other measurement device. Other factors, such as long-term stability, conversion factors, temperature/pressure coefficients and process conditions vs. calibration conditions impact the actual process accuracy.

To get an apples-to-apples comparison of MFC accuracy, it is important to understand the above elements of accuracy and how they relate to the device specifications. Some MFC manufacturers include all three elements in their accuracy statement, some do not. For assistance selecting the most accurate MFC for your application, please contact our Applications Engineering team or your local Brooks Instrument representative.

Sparging with Mass Flow Controllers Makes Wine Taste Better

May 23rd, 2016 Comments off

Sparging is injection of a gas into a liquidMerriam Webster defines sparging as: to agitate (a liquid) by means of compressed air or gas entering through a pipe. A simpler explanation is: sparging is the injection of a gas into a liquid. The method used to expose the gas to the liquid varies and these systems are called aerators, bubblers, carbonators, diffusors or injectors. The most recognizable example is the bubbler in a fish tank.

Where Sparging is Used
The sparging of CO2 and O2 in bioprocessing controls the pH and dissolved O2 levels required to maintain the ideal fermentation environment in bioprocessing. The control of the pH by sparging is also utilized in water treatment and many refining processes. Removal of contaminants that are absorbed by a sparged gas (stripping) is critical in many medical and purification applications.

Sparging in the Food & Beverage Industry
Though sparging applications are plentiful in many industries, the applications in the food and beverage industry impact our daily lives. Carbonating sodas and beer is an obvious application. Spargers are used extensively to lower the O2 content in order to increase the shelf life of juices, oils and processed foods. The injection of gases for foaming or increasing bulk volume is common in dairy processing and can be seen on the store shelves as whipped or light. Here in California wine country, sparging is critical to controlling the oxidation processes that determine the subtle variations in wine taste and aroma.

The Need for Precision Flow Control When Sparging
The benefits of controlling critical process variables to tighter ranges are driving the need for precision flow control in sparging applications. Brooks Instrument supplies products that measure the sparged gases and controls the rate that the gases are exposed to the liquid. Our SLA5800 Series Mass Flow Controllers & Meters (MFCs) offer high accuracy over a wide range of flows and pressures, while the SLAMf Series Mass Flow Controllers & Meters are engineered with a NEMA4X/IP66 enclosure for installation in environments where dust, moisture, temperature extremes or wash-down requirements are an issue.