The Importance and Uses of Variable Area Flowmeters (Rotameters) in Industrial Applications

Variable area flowmeters, known as rotameters, have long been a staple in various industries, from chemical processing to water treatment. They offer a simple yet effective method for measuring the flow rate of liquids and gases. Understanding the importance and the vast array of applications they serve can underscore the reason behind their continued relevance in the industrial landscape.

How Does a Rotameter Work?

Before diving into its uses and importance, it's essential to grasp the basic operation of a rotameter. A rotameter consists of a tapered tube, typically made of glass or clear plastic, with a float inside. As fluid flows through the tube, it raises the float. The float's height corresponds to the flow rate, read from a scale marked on the tube.

The float's upward movement is due to the balance between the buoyant force exerted by the fluid and the gravitational force pulling the float downwards. When these forces reach equilibrium, the float stabilizes at a particular height, allowing for flow rate measurement.

Importance of Rotameters in Industrial Applications

Simplicity and Reliability: Rotameters have no moving parts other than the float itself, resulting in less wear and tear and ensuring a long service life. Their simple design means fewer points of failure, translating to increased reliability.

• Cost-Effective: Due to their uncomplicated design and construction, rotameters are generally more affordable than many other flowmeter types, making them a preferred choice for applications where cost is a significant concern.
• Direct Readout: Rotameters provide an immediate visual indication of the flow rate, eliminating the need for additional electronic devices or readout systems, particularly useful in environments where electronic instrumentation may be impractical or undesirable.
• Flexibility: Rotameters apply for both liquids and gases, provided the appropriate float material and tube size are selected.
• Low Maintenance: With few moving parts and no electronic components, rotameters require minimal maintenance, reducing operational downtime.
• No Power Requirement: Rotameters operate without external power sources, making them ideal for locations where power availability is a challenge.

Common Uses of Rotameters in Industry

• Chemical Processing: Rotameters are extensively used in chemical plants to monitor and regulate the flow of raw materials, intermediates, and finished products. Their ability to handle aggressive chemicals, assuming construction with compatible materials, makes them suitable.
• Water Treatment: In water treatment plants, rotameters help monitor and control the flow of water and treatment chemicals, ensuring effective treatment and efficient plant operation.
• Gas Distribution: Industries that utilize various gases, like nitrogen, oxygen, or carbon dioxide, use rotameters to monitor and regulate gas flow, ensuring optimal process conditions.
• Pharmaceuticals: Ensuring precise flow rates is crucial in the pharmaceutical industry. Rotameters help regulate the flow of solvents, active ingredients, and other fluids, maintaining the consistency and quality of drug products.
• Laboratories: Rotameters are commonly found in research and analytical labs, allowing scientists to control the flow of gases or liquids in experiments precisely.
• Food and Beverage: The food industry uses rotameters for tasks such as regulating the flow of ingredients in food processing or managing cleaning agents in CIP (Clean-In-Place) systems.
• HVAC Systems: In heating, ventilation, and air conditioning (HVAC) systems, rotameters help ensure the proper flow of refrigerants and other fluids, guaranteeing system efficiency.

In the vast landscape of industrial applications, rotameters stand out for their simplicity, reliability, and versatility. Whether dealing with chemical processing, water treatment, or any other industry, having a dependable flow measurement device cannot be overstated. With its proven track record, the variable area flowmeter continues to be a valuable tool in various sectors, underlining the time-tested principle that, sometimes, simplicity is the highest form of sophistication.

Miller Energy, Inc.

https://millerenergy.com

800-631-5454

Thermal Mass Flow Controllers & Meters for the Harshest Environments

Thermal Mass Flow Controllers (MFCs) play a crucial role in process control applications by precisely and accurately controlling gas flow rates in various processes. They are used across multiple industries and applications to ensure stable, repeatable, and efficient process conditions. Some of the critical areas where Thermal MFCs are applied include:

1. Semiconductor Manufacturing: In semiconductor fabrication processes, such as chemical vapor deposition (CVD) and plasma etching, MFCs control the flow of process gases to maintain accurate gas ratios and reactant concentrations, ensuring consistent wafer quality.
2. Pharmaceutical and Biotechnology: MFCs apply in processes such as fermentation, cell culture, and gas chromatography, where they regulate the flow of gases like oxygen, carbon dioxide, and nitrogen to maintain optimal growth conditions for biological cultures or to separate and analyze various compounds.
3. Chemical Processing: In chemical synthesis and reaction control, MFCs manage the flow of reactants and carrier gases to maintain the proper stoichiometry and reaction conditions, ensuring high-quality product yields and safe operations.
4. Solar Cell Manufacturing: MFCs apply in processes such as thin-film deposition and chemical etching, where they control the flow of process gases to create uniform layers and achieve precise etching profiles for high-efficiency solar cells.
5. Fuel Cell Development: In fuel cell research and manufacturing, MFCs regulate the flow of hydrogen, oxygen, and other gases to maintain optimal conditions for efficient energy production and long-lasting performance.
6. Environmental Monitoring: MFCs are used in air quality monitoring and emissions testing systems to control the flow of calibration gases, ensuring accurate measurements and compliance with environmental regulations.
7. Laboratory Research: In various research applications, such as mass spectrometry, gas chromatography, and flow chemistry, MFCs provide precise control over gas flow rates for accurate analysis and experimental conditions.

Thermal Mass Flow Controllers are essential components in process control systems, providing the accuracy, precision, and repeatability required for maintaining optimal process conditions and ensuring high-quality results across diverse industries and applications.

Brooks Instrument SLAMf Series Thermal Mass Flow Controller

The Brooks Instrument SLAMf Series Thermal Mass Flow Controller is an innovative and cutting-edge solution for accurately controlling and measuring gas flow in a wide range of industries and applications. This state-of-the-art flow controller meets the highest performance, reliability, and flexibility standards, ensuring seamless integration into your process control systems.

The SLAMf Series boasts several unique features that set it apart from its competitors. With its patented MultiFlo™ technology, users can easily configure the controller for multiple gases and flow ranges without sacrificing accuracy or requiring recalibration. This results in a highly versatile device capable of meeting the demands of diverse applications.

Another standout feature of the SLAMf Series is its ultra-fast response time, facilitated by the advanced sensor design and high-speed digital signal processing. It ensures that your processes are consistently controlled with precision, minimizing the risk of variations and improving overall efficiency.

The robust construction and corrosion-resistant materials used in the SLAMf Series make it suitable for even the most challenging environments. Its compact design allows easy installation in tight spaces, making it an ideal choice for various industries, such as semiconductor manufacturing, pharmaceuticals, chemical processing, and research facilities.

Typical applications for the Brooks Instrument SLAMf Series Thermal Mass Flow Controller include gas mixing and blending, gas delivery, process control, and environmental monitoring. With its unparalleled performance, adaptability, and durability, the SLAMf Series is the ultimate choice for professionals seeking the best in flow control technology.

Miller Energy, Inc.
800-631-5454
https://millerenergy.com

Basics of Mass Flow Controllers (MFCs)

MFCs work by measuring the mass of the process fluid flowing through them and using this information to control the flow rate. They typically use a flow sensor to measure the flow rate and a control valve to regulate the flow. The control valve is usually a variable area flow meter or a valve that can be opened or closed to adjust the flow rate.

MFCs are used in a variety of applications, including chemical processing, semiconductor manufacturing, and environmental monitoring. They are often used to control the flow of gases in chemical reactions, to regulate the flow of fluids in manufacturing processes, and to monitor and control the flow of gases in environmental monitoring systems.

MFCs are highly accurate and precise and can maintain a constant flow rate over a wide range of process conditions. They are also relatively easy to install and maintain and can be integrated into various process control systems.

There are many applications for mass flow controllers (MFCs) in process control. Some examples include:

• Chemical processing: MFCs can be used to control the flow of reactants and catalysts in chemical reactions, ensuring consistent product quality and yield.
• Food and beverage processing: MFCs can be used to control the flow of ingredients in the production of beverages, sauces, and other food products.
• Pharmaceutical manufacturing: MFCs can be used to control the flow of active ingredients and excipients in the production of medications.
• Petrochemical processing: MFCs can be used to control the flow of fluids in the refining and processing of oil and natural gas.
• Environmental control: MFCs can be used to control the flow of gases and liquids in air pollution control systems, water treatment plants, and other environmental applications.
• Semiconductor manufacturing: MFCs can be used to control the flow of gases and liquids in the production of semiconductor devices.
• Aerospace and defense: MFCs can be used to control the flow of gases and liquids in a variety of aerospace and defense applications, including propulsion systems, life support systems, and fuel systems.

For more information about mass flow controllers in NY, NJ, PA, DE, MD and OH contact Miller Energy, Inc. Call 800-631-5454 or visit https://millerenergy.com.

Brooks Instrument GP200 Pressure-based Mass Flow Controllers (MFC): Theory of Operation

Brooks Instrument presents the theory of operation behind their pressure-based mass flow controller (P-MFC) from their GP200 series in this video. This P-MFC has a unique design approach for enhanced process performance without the limitations of today's traditional P-MFCs. A traditional P-MFC system includes:

• An upstream pressure transducer.
• An upstream control valve.
• Two individual pressure transducers.
• Laminar flow element.

The use of an upstream valve has many disadvantages. This design requires high pressure making it sub-optimal for critical low-pressure gases and low full-scale flow rate. It also means matching the two individual pressure transducers perfectly. 

Brooks Instrument designed a patented integrated differential pressure transducer, GP200 P-MFC, to address the disadvantages. The GP200 has one actual differential transducer instead of two, eliminating the need to match the two individual pressure transducers, significantly reducing measurement uncertainty, and improving accuracy, particularly for critical low vapor pressure process gases. Its downstream valve architecture will operate at much lower inlet pressures and across a broader range of pressures. The downstream valve also minimizes the bleed-down effect and ensures that the device is insensitive to dynamic outlet conditions.

The GP200 Series P-MFC features a patented architecture that overcomes the limitations of conventional P-MFCs to provide the most precise process gas delivery even when delivering low vapor pressure process gases. It includes several unique design aspects, including an integrated differential pressure sensor coupled with a downstream valve architecture enabling the most precise process gas delivery over the industry's broadest range of operating conditions.

Since GP200 Series supports a broad range of process conditions, it can be used as a drop-in replacement and upgrade for many traditional P-MFCs and thermal MFCs. It reduces the complexity and cost of ownership of the gas delivery system because it eliminates the need for components such as pressure regulators and transducers.

GP200 FEATURES

• True differential pressure measurement
• Lower inlet pressure operation
• Downstream valve architecture
• Matched transient response
• Zero Leak-by Control Valve
• MultiFlo™ technology offers unparalleled flexibility—one device can be programmed for thousands of different gas and flow range configurations without removing the MFC from the gas line or compromising accuracy
• Local display indicates flow, temperature, pressure and network address
• DeviceNet™, EtherCAT®, RS-485 L-Protocol and analog interfaces

GP200 BENEFITS

• By removing the requirement to match and compensate two separate pressure transducers, the GP200 differential pressure technology reduces measurement uncertainty for enhanced accuracy, repeatability and drift performance.
• Safer fab operation at lower inlet pressures is now achievable with a P-MFC due to the GP200 differential pressure sensor that is specifically optimized for low differential pressure measurement.
• The downstream valve architecture ensures accuracy is independent of downstream pressure, enabling flow delivery into pressures as high as 1200 Torr. The fast closing valve addresses non-productive recipe wait times, or "tail effects," seen in upstream MFC valve designs that require additional time to bleed down their internal volume of gas.
• Ultra-fast, highly repeatable ascending and descending flow stabilization time enables tighter process control in advanced high cycle Deposition and Etch processes.
• 100X improvement in valve shut-down
• With MultiFlo™, MFC full scale flow range can be re-scaled down typically by a factor of 3:1 with no impact on accuracy, turndown or leak by specifications, for optimum process and inventory flexibility 
• Convenient user display and independent diagnostic/service port aids device installation, monitoring and troubleshooting

For more information about Brooks Instrument products, contact Miller Energy, Inc. Call 800-631-5454 or visit https://millerenergy.com.

How Does a 250:1 Turndown Improve Your Bioprocess Performance?

The Brooks Instrument SLA Series Biotech Mass Flow Controller (MFC) with a 250:1 turndown delivers critical benefits to your bioprocess. This biotech-focused MFC provides the added flexibility of a higher controllable range than a traditional MFC, enabling easy scaling and reducing the total cost of ownership by requiring fewer gas lines and mass flow controllers in the system configuration. Performance of the bioprocess also improves by reducing DO noise while fewer overall components simplify system maintenance. 

For more information about Brooks Instrument products, contact Miller Energy by calling 800-631-5454, or visit https://millerenergy.com.

GT1600 Industrial Glass Tube Variable Area Flowmeter (Rotameter) for Liquids & Gases

As one of the pioneering manufacturers in variable area (VA) flow meter (rotameter) technology, Brooks Instrument has created a diverse and proven portfolio of gas flow meters, installed and used across virtually every industry.

The NEW Brooks Instrument GT1600 Series industrial design is ideal for the toughest applications. 

GT1600 Features

• Configurable to retro-fit GT10xx, GT130x and Full-View
• 360 degrees rotatable viewing angle
• High quality materials for safety, in- and outdoor durability
• 316 stainless steel frame
• Polycarbonate safety shield
• 316/316L dual certified stainless steel process fittings
• Alarms for high- and low flow (optional for all flow ranges, either at time of
• order,or as add-on in the field)
• Flanged or threaded connections, available horizontal and vertical
• Panel- and wall mount options
• Easy in-situ maintenance: Clean or replace tube and float without removal from
• the process piping
• Adjust the scale to compensate for process variation
• Optional integral needle valve

For more information about the Brooks Instrument GT1600 contact Miller Energy, Inc. Call them at 800-631-5454 or visit their website at https://millerenergy.com.

Understanding the Operation of Mass Flow Controllers (MFCs)

The basic construction of mass flow controllers (MFCs) consists of four main components. A body, a thermal sensor, a printed circuit board, and a magnetic control valve. As gas enters the flow body, a laminar flow element or restrictor diverts a precise portion of the gas to pass through the thermal sensor. The thermal sensor is the heart of the mass flow controller and consists of a bypass tube fitted with a heater element and two temperature sensors. As gas enters the sensor bypass tube, the upstream and downstream temperature sensors measure the temperature differential between gas entering the bypass tube and exiting it. 

When choosing an MFC supplier, consider whether the manufacturer provides zero stability specifications, also known as sensor stability, which indicates the device's ability to maintain accuracy over time. Good sensor stability ensures the MFC delivers highly accurate and consistent results with less frequent recalibration or replacements needed. A stable, precise sensor guarantees regular, precise process control. As the thermal sensor measures the change in the flow temperature,  it sends a signal to the circuit board, which interprets the data into flow output and compares it to the setpoint received from the user setpoint signal. If the setpoint, or required value, is higher than the measured value or flow output, the controller will open the control valve, letting more flow through. Suppose the setpoint is lower than the flow output. In that case, the control valve will close, decreasing flow, caused when a coil inside the magnetic control valve sends an electrical current around a valve stem, which moves the valve plunger by thousands of an inch. The circuit board is the device's brain, so pay close attention to the electronics and firmware architecture when evaluating an MFC. The MFC should have the ability to support advanced alarms and diagnostics to monitor and correct issues before the overall process is negatively affected. Check to see what built-in alarms and diagnostics are available. 

Brooks Instrument devices support flow output and additional alerts like flow totalization, valve drive, flow obstruction, and calibration. All Brooks devices are tested as complete systems to ensure robust and accurate operation and maintain calibration to international standards. 

In Pennsylvania and Ohio, contact Miller Energy to learn which Brooks Instrument solution is right for your process.

In Eastern Pennsylvania:
Phone: 610-363-6200

In Western Pennsylvania:
Phone: 412-257-0200

In Ohio:
Phone: 440-735-0100

https://millerenergy.com

Brooks Instrument Sponsoring $2000 Engineering Scholarship

CLICK THIS LINK TO LEARN MORE

Brooks Instrument is committed to the next generation of engineers. Accordingly, they have established a $2,000 scholarship for a qualified student enrolled in an engineering program at an accredited college or university. Learn more here (https://www.brooksinstrument.com/en/about-us/scholarship).

Flow & Pressure Instrumentation for Biopharmaceuticals & Life Sciences

Producing biopharmaceuticals is one of the world’s most demanding manufacturing processes.

Brooks Instrument’s mass flow and pressure control technology helps maximize cell culture yields and control bioprocess costs. Their flow
and pressure controllers set global standards for reliability, repeatability and long-term stability.

Brooks Instrument mass flow controllers (MFCs) satisfy key biotechnology research and production requirements:

• Tight control of DO and pH during experiments and production
• NO unplanned downtime due to high cost of losing a batch or experiment
• Ability to rapidly diagnose and resolve issues with bioreactors or fermentation equipment
• Cost-effective method for adhering to regulatory requirements
• Excellent technical support and rapid response for equipment service

To read the entire Flow & Pressure Instrumentation for Biopharmaceuticals & Life Sciences guide from Brooks Instrument, download it here. Alternatively, browse the embedded document below.

Flow & Pressure Instrumentation for Biopharmaceuticals & Life Sciences from Miller Energy, Inc.

Mass Flow Controllers for Precise Dosing

Mass Flow Controller - Cutaway View
Image courtesy Brooks Instrument 

There are processing applications that require very accurate flow or dosing control of added constituents. The applications are diverse, ranging from controlled gas flow to precise metering of product fluid components. The ability to accurately and reliably measure and regulate mass flow of a fluid into a process is a common task in process measurement and control.

Thermal mass flow measurement, in basic operation, infers mass flow by measuring the heat dissipation from a heated temperature sensor and comparing it to an unheated reference temperature sensor. The heat dissipation is directly proportional to the mass flow of gas or liquid.

Thermal mass flow meters are very popular for several reasons. They have no moving parts, have a fairly unobstructed flow path, are accurate over a wide range of flow rates, calculate mass flow rather than volume, measure flow in large or small piping systems, and do not need temperature or pressure compensation.

For a process control application, accuracy and real time delivery of measurement data are key factors. Advanced smart controls with a range of communications options that will interface with a variety of devices across a choice of platforms bring high levels of functionality and ease of use to an application. For gas applications, smart technology allows one device to be applied to multiple gas types and ranges without removing the flow meter from the system. Product selection is enhanced by the availability of instruments targeted at a range of applications.

Share your flow measurement and control challenges with process measurement and control specialists. Leverage your own process knowledge and experience with their product application expertise to develop effective solutions.

Using Brooks Mass Flow Controllers with LabVIEW™

Coriolis mass flow controller
Image courtesy Brooks Instrument

Brooks Instrument is the manufacturer of highly accurate and repeatable mass flow controllers. LabVIEW™ develops integrated software for building measurement and control systems used in laboratories, universities, and pilot manufacturing plants. The combination of Brooks MFCs and LabVIEW software provides users a great option for measurment, control, data acquisition and data storage for mass flow.

Listed below are some of the more convenient communication methods to tie Brooks MFCs and LabVIEW™ software together.

Analog Signal Interface

In many situations LabVIEW™ software users also use analog to digital
I/O cards. With analog input cards, users can run their mass flow controllers utilizing a standard 0-5 volt or 4-20 mA analog signaling via LabVIEW™. This is a time-tested, traditional approach and is recommended for applications without the availability of digital control systems.

RS485 Digital Interface

Brooks Instrument mass flow devices configured with RS485 communications (must have the ‘S’ communications option) provide RS485 digital communications via a 15-pin D connector. The RS485 digital signal is passed directly to a computer running LabVIEW™ through a serial RS485 converter. Brooks models GF40, GF80 and SLA Series mass flow controllers are available with the ‘S’ communications option.

Its valuable to note that there is also a free set of VI file for use with LabVIEW from Brooks. These can be loaded directly into the LabVIEW™ application and provide the basics required to create a LabVIEW control interface using the S-Protocol digital command structure. The VI files are available for download from the Brooks Instrument website.

Another communications alternative is using Brook’s Smart DDE (Dynamic Data Exchange) software 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. While not a complete turnkey option, it greatly reduces the amount of code required to communicate between LabVIEW and the mass flow controller.

DeviceNet Digital Signal Interface

Brooks models GF40, GF80 and SLA, configured for DeviceNet digital communications, can also be controlled via the LabVIEW™ application provided a National Instruments DeviceNet interface card, associated drivers, and software are used. These additional items support the development of application interfaces using LabVIEW™ software for Windows and LabVIEW™ Real-Time.

According to 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.

Share your mass flow measurement and control challenges with application experts, leveraging your own knowledge and experience with their product application expertise.

Sometimes the Simple Solution Is the Best

This metal tube variable area flow meter is reliable,
accurate, and requires little maintenance
Photo courtesy Brooks Instrument

For process control and commercial or industrial applications, there are numerous methods of flow measurement from which to choose. Technologies range from very simple applications of physical principles to deployment of very specialized electronics and sensors. The available range of accuracy, response, and cost is quite broad, with a general expectation that higher cost will deliver better performance and accuracy.

Making the best instrument selection for a flow measurement application should include an assessment of what the operators really need in order to safely and effectively run the process or perform the task related to the measurement of fluid flow. Installing instrumentation with capabilities far beyond what is required is almost certainly a waste of financial resources, but may also have an unexpected impact on operators. Through the generation of data that, while accurate, does not provide any actionable information about process condition, operators can be misled, similar to the occurrence of a false or nuisance alarm. Some applications call for high accuracy, some do not. Define your informational needs and select instruments that will meet those needs.

There is a large array of applications that can be satisfied with simpler, less costly measurement technology. These devices often employ turbines or vanes to produce an indication of flow rate. Incorporated into some of the instruments is a means to visually observe the flowing liquid to verify color and clarity. Simple devices sometimes are intended only to indicate the presence of fluid flow, and whether the flow rate is high or low. Configurations are available that allow insertion into lines under pressure (hot tap) through a full port ball valve. Other variants with combinations of features and capabilities abound.

The selection range is enormous, so define your minimum needs first, then search for a compatible product. Your search can be enhanced by contacting an instrumentation specialist. Combining your process expertise with their broad product knowledge will produce effective solutions.

Metal Tube Variable Area Flow Meter from Miller Energy, Inc.

Quick Reference Guide for Pressure and Flow Instrumentation

Mass Flow Controller
Courtesy Brooks Instrument

Brooks Instrument is a globally recognized manufacturer of flow and pressure instrumentation for scientific and industrial use. The company's product line ranges through:

Variable Area Flowmeters - Armored metal, glass tube and plastic for reliable measurement of liquids and gases

Mass Flow Controllers - Coriolis and thermal mass flow technology for precision fluid measurement and control

Pressure Controllers - Digital and mechanical pressure regulators and controllers deliver high precision gas control

Pressure and Vacuum Products - Pressure transducers, gauges, and capacitance manometers

Vaporization Products - Deliver controlled high purity vapor to processes from source liquid

There are many products and variants. The company developed a summary document that provides an overview of the various product types, enabling potential users to focus quickly on the instruments that will meet their requirements. The document is included below.

Share your pressure, vacuum, and flow measurement and control challenges with product application specialists, combining your process knowledge and experience with their product application expertise to develop effective solutions.

Flow, Pressure & Vapor Instrumentation from Miller Energy, Inc.

Use Electronic Pressure Controllers in Your Research Process Loop to Eliminate Droop, Boost, and Hysteresis

(re-blogged with permission from Brooks Instrument)

Gas pressure control is critical in many applications like life sciences and chemical/petrochemical research where flow is an integral part of the process. Brooks Instrument electronic pressure controllers can be used as they require flow to function. Compared to using a mechanical pressure regulator, electronic pressure controllers eliminate droop, boost and hysteresis, offering stable pressure control.

There are two configurations available for pressure control – upstream and downstream. This terminology is somewhat unique to Brooks Instrument electronic pressure controllers.

Downstream vs. Upstream Pressure Control

Downstream pressure controllers maintain the pressure downstream of the device itself, increasing flow to increase the pressure and decreasing flow to decrease the pressure. For this reason, this is called direct acting. This configuration is commonly called a standard pressure regulator. A downstream pressure controller acts very similar to a typical mass flow controller because they are both direct acting.

Upstream pressure controllers maintain the pressure upstream of the device itself, increasing flow to reduce the pressure and decreasing flow to increase the pressure. For this reason, this is called reverse acting. This configuration is commonly called a back pressure regulator in the industry.

Selecting and Sizing an Electronic Pressure Controller

The following information is required to select and size a Brooks Instrument electronic pressure controller:

• Process gas
• Maximum flow rate being used to maintain pressure -The “sweet spot” for pressure control is between 100 SCCM and 5 SLPM.
• Calibration pressure (maximum pressure to be controlled)
• Reference pressure (for upstream controllers the reference pressure is the downstream pressure and for downstream controllers the reference pressure is the upstream pressure)

As long as flow is present in a process you will typically find the need for some type of pressure control. Vessel sizes up to 30 liters commonly use flow rates up to 3 SLPM during their process steps. Brooks Instrument pressure controllers are a perfect fit for these services, offering stable pressure control with no droop, boost or hysteresis, which are commonly experienced when using a mechanical pressure regulator.

Typical Bioreactor Process Using an Upstream Pressure Controller

"Bubbler Method" Liquid Level Measurement

An accurate pressure transmitter
is an integral part of  a liquid level
measurement system using the
"Bubbler Method"
Courtesy Brooks Instrument

Measuring liquid level in a tank or vessel can be accomplished in a number of ways, all of which require some arrangement of instrumentation to either infer the liquid level from the measurement of a related physical property, or directly deliver the liquid level visually using a scaled gauge arrangement. One indirect method of level measurement is often referred to as the bubbler method, so named because it employs a purging gas that continually vents from the bottom of a tube extending into a tank of liquid. Through a simple apparatus, the level of a liquid can be inferred by the amount a back pressure exerted upon the gas flowing through the tube.

Probably the greatest advantage of this method of liquid level measurement is that the liquid does not contact the sensing instrumentation. The only portion of the apparatus in contact with the liquid is a tube immersed into the tank. Basically, a purge gas flows through the immersion tube and may bubble out the immersed end of the tube, which is open to allow the contained liquid to exert a hydrostatic pressure on the purge gas. The back pressure on the gas that is exerted by the liquid contained within the tank will vary directly with the depth of the liquid. The back pressure can be correlated to a liquid level. Further calculations, which would include the tank shape, dimensions, and the liquid density can provide an indication of the volume and mass of the liquid. Here is an illustration of the setup, provided courtesy of Brooks Instrument, globally recognized leader in flow and pressure measurement and control. The illustration is from Brooks' January blog article.

Bubbler Method Tank Level Measurement Apparatus, showing application of some Brooks Instrument devices.

Below are data sheets detailing the components used in the system to control and measure the gas flow, and measure the back pressure on the immersion tube. There are other components needed for a complete system, but they are fairly generic in nature and easily obtainable. Contact a flow and level measurement specialist with your application challenges and work with them to produce effective solutions.

Bubbler Method Liquid Tank Level Measurement Instruments from Miller Energy, Inc.

Factors For Selecting a Variable Area Flow Meter (Rotameter)

Three of many configurations of
variable area flow meters.
Courtesy Brooks Instrument

Industrial processes have many instances where fluid product components, liquid or gaseous, are moving within pipes. Processing is about control, so it follows that an input to the control, measurement, or data logging centers of the facility will answer the question, "How much is flowing through that pipe?".

There are numerous methods employed for quantifying flow in the industrial process measurement and control field, each with particular attributes that may be considered advantageous under  certain operating conditions. All flow measurement methods are indirect, as their actual measurement is of a property that is impacted in a predictable manner by a change in the flow. Flow measurement is an essential element that, combined with other fluid attributes, is used to calculate the total mass of a fluid that has traversed the measurement point.

One time tested method of measuring flow is the variable area meter, also called a rotameter.

Operation of the variable area meter (also referred to as a VA meter) is based upon creating an equilibrium between an upward force, produced by the fluid motion, and a downward force, gravity. The device includes a tapered glass or metal tube that encases a specially shaped float, often referred to as a shaped weight. VA meters must be installed vertically, with the media flowing from the bottom upward, so that the gravitational force necessary for operation is properly aligned with the flow direction. As fluid flows upward through the specially tapered tube, it creates drag on the float contained within the tube, lifting it upward. As the float rises, the free area between the float and the tube wall increases, causing a reduction in the fluid velocity and drag force. For any given flow volume, the flow velocity within the tube will cause the weight to rise until the drag force created by the flow reaches equilibrium with the countervailing force of gravity on the float. Proper design of the tube and the float allow for direct indication of flow volume.

Some of the attributes of variable area meters include:

• No external power or fuel required for operation
• Must be installed vertically, with flow entering bottom
• Meters are characterized to a specific substance, at a specific temperature
• Operation is stable, with low pressure drop
• Requires constant gravity for operation
• Direct local readout of flow rate with meter or scale imprinted on tube
• Glass tube based unit flow readings require visibility of float through the medium
• Accuracy is comparatively low for an industrial flow measurement device
• Generally low maintenance, simple construction, low comparative cost

Brooks Instrument, a world renowned manufacturer of flow, pressure, and level measurement instruments, has produced a concise and compact white paper that summarizes the factors to consider when specifying a VA meter, as well as how each factor impacts operation of the unit. The description is practical and easily understood. It is recommended reading for all process stakeholders to build their flow measurement knowledge.

I have included the paper below. Browse the paper. Contact the flow instrumentation specialists to discuss your application requirements and challenges. Combining your process know-how with their product application knowledge will produce a good solution.

Selecting Variable Area Flow Meters for Process Measurement from Miller Energy, Inc.

Thermal Mass Flow Controller - Product Enhancement

Newly Enhanced Thermal Mass Flow Meters
And Electronic Pressure Controllers
Courtesy Brooks Instrument

Brooks Instrument, world recognized leader in thermal mass flow controllers and mass flow meters, has improved upon its premier family of smart digital thermal mass flow controllers and meters. The newly enhanced SLA Series features:

Enhanced temperature stability
Upgraded electronics
Improved accuracy
Zero-drift diagnostics
High turndown ratio

Multiple communication protocol support, and more.

The video included below will show you all the latest improvements on this product line that has thousands of units in its installed base throughout many industries and applications.

Application assistance and detailed information is available from product specialists. Combine their product and application knowledge with your own process expertise to generate a positive outcome.