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

July 25th, 2016 No comments
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 No comments

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.

CMC
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/

Repeatability
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.

Linearity
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 No comments

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.

Is your MFC displaying/outputting a flow signal (or negative flow) with no gas going through the device?

April 19th, 2016 Comments off

There are many reasons why this can occur, such as a change in mounting orientation, ambient temperature, or process pressure. While mass flow controllers (MFCs) from Brooks Instrument are known for stability and minimal long-term drift, the flow signal or process variable (PV) from an MFC may drift over time.

To ensure the best possible accuracy, it is recommended to zero the MFC at initial installation and periodically thereafter. The best way to know when your MFC needs to be re-zeroed is to see if there is flow signal (positive or negative) at a zero flow condition. Keep in mind, MFC valves are precision control valves, not positive shut off valves, so a small amount of valve leak-by may exist.

To zero your device, it is recommended that you follow these steps:

  • Allow for a warm-up time of at least 45 minutes to get to normal operating temperatures
  • It is preferable to zero at process conditions (meaning inlet pressure should be the same as the normal device operation)
  • Close a downstream shutoff valve and open the MFC valve using a setpoint or valve override (VOR) open command. This will fill the lines up to the shutoff valve and pressure will equalize across the MFC.
  • Allow 30 seconds minimum for stabilization
  • Monitor the output (PV) signal
  • For digital devices, press the zero button until the LEDs indicate the device is re-zeroing. The LED indicator turns green when the zero process is complete. PV signal should be at zero. Repeat if necessary.
    • Alternatively, digital devices can be re-zeroed using service tools (BSS or BEST) from Brooks Instrument.

Zero Button on MFC

  • For analog devices, monitor the output signal and adjust the zero potentiometer until zero is achieved.
  • Remove VOR open command and/or set point
  • Open the downstream shutoff. Monitor the PV for any flow indication. If you are seeing flow, this could be the valve leak-by as described above.

Brooks Instrument MFCs are zeroed at the factory. An initial zeroing may be necessary upon installation. By setting up the device, as outlined in the first five steps above, you can determine whether an initial zeroing is needed, or if it is good to go.

If you need assistance please contact our Technical Services team or your local Brooks Instrument sales representative for assistance.

How to Set-up Multiple MFCs in an RS485, Multi-drop Network

March 2nd, 2016 Comments off

Many options are available when setting up an RS485 network. The goal, of course is to get better control of your system. There are some solutions that make setting up both small and large RS485 networks easy. Digital MFC’s and electronic pressure controllers from Brooks Instrument include an RS485 communications option, typically utilizing the Smart protocol.

Small Networks – Less Than 10 Devices For a smaller network of less than 10 devices, a simple non-powered, USB-to-RS485 converter can be utilized. However, here, we will show an off-the-shelf turnkey solution that uses a powered converter. An example of a turnkey solution is:

•Brooks Smart Interface software, and
•0260 power supply/converter

RS485 Network Set-up for Less Than 10 MFCs

Large Networks -10 or More Devices For a larger network of 10 devices or greater, a powered converter should also be selected for best performance results. The 0260 power supply/converter from Brooks Instrument along with the Smart interface software can control up to 30 devices. Both of these products will communicate with any Brooks Instrument MFC or electronic pressure controller with the RS485 Smart Protocol, such as the GF40, GF80 and SLA5800 Series. Other than the 0260 power supply, the only piece of hardware required to set up the network is a multi-drop cable. The images below show different ways to set-up a network with more than 10 devices. RS485 Network Set-up for 10 or More MFCs The Brooks Smart Interface software and hardware will work independently. For users that have their own software tools, the 0260 hardware can be used as a power source and signal converter. Additionally, the Brooks Smart Interface software can be used in conjunction with hardware already in place. RS485 Network Optional Set-up for 10 or More MFCs If you need assistance setting up devices in an RS485 network, please contact our Technical Services team or your local Brooks Instrument representative for assistance.

Liquid Level Measurement Using the “Bubbler Method”

January 29th, 2016 Comments off

Liquid Level Measurement Using the Bubbler Method
Industry
General chemical industry applications where liquids are stored in tanks.

Application
Measurement of the level of a liquid in a tank using a pressure transmitter to measure the pressure created by the weight of the liquid. The key feature of this method is the use of a small diameter (typically ¼”) tube installed in the tank to allow the pressure measurement to be taken at the top of the tank, eliminating potential leak points at the bottom of the tank.

Process Details
The pressure measured at the bottom of a tank of liquid will be proportional to the level of the liquid in the tank according to the relationship:
Height of liquid = Pressure at bottom of tank / density of liquid.
To avoid possible leak points, the pressure measurement can be taken at the top of a “dip tube” installed in the tank as shown in the diagram above. The key to this method is the introduction of a low rate of gas flow in the tube, effectively transferring the pressure at the bottom of the tank to the inlet of the tube (plus the small pressure drop created by the flow rate in the tube).
To keep the pressure drop low in the tube, a flow rate of 1.0 SCFH is typical for a ¼” diameter dip tube. This minimizes the offset in the level measurement created by this pressure drop.

Instrumentation
Using a Brooks Instrument Model 1350G purgemeter with a Model FCA8900 integral downstream flow controller will keep the flow rate constant in the dip tube with the varying downstream pressure caused by the varying liquid level. This further improves the accuracy of the measurement by keeping the offset constant.
The supply pressure to the flowmeter should be set to a value high enough to overcome the back pressure of the liquid level and the minimum pressure drop needed across the flow controller. A supply pressure of 25 psig would be adequate for tank levels up to 30 feet. The flowmeter scale should be sized (i.e. compensated) for this supply pressure.

Also available from Brooks is the SolidSense II® pressure transducer for the primary electrical output.
Brooks Instrument has been a supplier of choice for this application for many years, and to several industries, including petroleum refining, electrical power and semiconductor.

Selecting the Right Elastomer Seal Material for Mass Flow Controllers and Variable Area Flow Meters (Rotameters)

December 30th, 2015 Comments off

Elastomer seal material selection is not always a clear cut decision. Many factors must be considered:

  • Fluid
  • Temperature
  • Pressure (Max, Min, Differential)
  • Application (static or dynamic)
  • Price
  • Customer’s experience

Most major seal manufacturers offer material compatibility information and material selection guides. Compatibility ratings are based on a manufacturer’s compound/material in a specific service. Published compatibility guides list one service at a time (glycol) at a nominal temperature (70º F).

While Brooks Instrument should not be considered an expert in elastomers, we will make recommendations based on our prior application experience. The final decision is of course, always up to the customer. To aid with your next decision on elastomer seal material the following are generic elastomer property descriptions for materials found in Brooks mass flow controllers and variable area flow meters (rotameters):

Fluorocarbon, VITON® (FKM):

VITON® is the trade name for DuPont Performance Elastomers Fluorocarbon or FKM material. FKM has a temperature range of -20F to +400F, and provides excellent resistance to a wide variety of chemicals, weather and compression set requirements. The relatively high level of fluorine in FKM materials allows for exceptional resistance to chemical attack, but with limited low temperature capabilities. Brooks offers FKM elastomers manufactured to conform with FDA and USP Class VI requirements, making it ideal for use with bio-pharm applications and medical devices.

Nitrile, Buna-N (NBR):

Nitrile, also known as Buna-N or NBR, is a copolymer of Butadiene and Acrylonitirle. It is the most commonly used elastomer for sealing products. It has a temperature range of -40F to +250F and is exceptionally resistant to petroleum based oils and hydrocarbon fuels. Nitrile materials also exhibit excellent tensile strength and abrasion resistance properties. The material performs well with most diluted acids, silicone oils and lubricants and in water applications. It is not recommended for use with ketones, aromatic hydrocarbons and phosphate ester hydraulic fluids.

Kalrez® Perfluoroelastomer (FFKM):

Kalrez® Perfluoroelastomer (FFKM) currently offers the highest operating temperature range up to 320°C (608°F), the most comprehensive chemical compatibility, and the lowest off-gassing and extractable levels of any rubber material. FFKMs deliver an extreme performance spectrum that make them ideal for use in critical applications like semiconductor chip manufacturing, jet engines and chemical processing equipment.

Ethylene Propylene, EPDM, or EP (EP):

EP is a copolymer of ethylene and propylene, while EPDM is a terpolymer combining ethylene, propylene and a diene monomer. EP materials offer a temperature range of -65F to +300F and offer excellent resistance to ozone, weathering, steam, water and phosphate ester type hydraulic fluids. Brooks offers EPDM elastomers manufactured to conform with FDA and USP Class VI requirements, making it ideal for use with bio-pharm applications and medical devices.

For exact product temperature ranges or material availability on a specific product, please refer to our product data sheets. Our long-tenured team of applications engineers will provide guidance, if requested, during the product selection and configuration process.

Handling Pressure Variation With a Mass Flow Controller

November 24th, 2015 Comments off

Industries: Petrochemical research, Alternative Fuels research

Application: Downstream destination of the fluid (normally gases) is a reactor vessel and the test requirements are broad from a pressure standpoint. This would typically apply when the pressure exceeds 200 PSIG.

optimum mfc system setup

 

Process Details and Specifications

Gases can range from hydrocarbons (i.e. methane, ethylene) to air, nitrogen, carbon monoxide and carbon dioxide. Pressures in the reactor vessel can range from a few hundred PSIG to several thousand PSIG.

Since an MFC is a closed loop control system with a valve that is sized for a specific set of conditions for optimum performance, pressure variations can significantly impact the performance of the valve. Simply stated, if an MFC is sized for higher pressures, then use at low pressures may result in an inability to achieve the required maximum flow through the valve. If an MFC is sized for lower pressures, then use at higher pressures may result in an oversized valve that is attempting to operate close to the fully closed position.

Instrumentation

The Brooks SLA Series MFC’s are particularly suited for these types of applications for two reasons:

- High pressure capability: up to 4500 PSIG operating pressures

- Brooks in-house valve sizing capabilities

Although research applications are all unique and can change over time, Brooks has the capability, both at the factory and with our sales partners, to provide expert consultation over a wide range of operating conditions. We’ll evaluate your specific needs to find a workable set of conditions to cover most, if not all, of your research testing needs.

The result is a reduction in the number of MFC’s needed to cover the entire range of your research, and eliminating the possibility of inadequate MFC performance, ensuring that all of your test data can be used.

Brooks has worked with all of the major petrochemical research facilities around the world, as well as many universities supporting these high pressure applications.

Categories: Coriolis and Thermal Mass Flow Tags:

Understanding Mean Time Between Failure (MTBF) for Process Instrumentation

October 28th, 2015 Comments off

Mean Time Between Failure (MTBF) is a measure of the reliability of a hardware product, component or system. MTBF is largely based on assumptions and the definition of failure and attention to these details is important for proper interpretation. For complex, repairable systems, failures are considered to be those conditions which place the device or system out of service and into a state for repair. Failures that can be left in an unrepaired condition, and do not place the device or system out of service, are not considered failures under this definition. In addition, units that are taken down for routine scheduled maintenance or inventory control are not considered within the definition of failure.

Brooks Instrument Illustrates How to Calculate Mean Time Between Failures (MTBF)

Calculating Mean Time Between Failures (MTBF)

 

The MTBF should not be confused with the life expectance. An example is the best way to describe the difference. All humans have a life expectance of 80 years or 700,800 hours. However, the human body fails at different rates depending on its age.

There are 500,000 25-year-old humans in a sample population. Over the course of a year, data is collected on deaths for this population. Throughout the year, 625 people died. The MTBF is (500,000/625)x24x365 = 7,008,000 hours (800 years). So, even though 25-year-old humans have high MTBF values, their life expectancy (service life) is much shorter and does not correlate.

 

How is MTBF calculated?

The Mean Time Between Failures (MTBF) of a product is determined using the following equation[1]:

Mean Time Between Failure (MTBF) Equation

Mean Time Between Failure (MTBF) Equation

 

F = number of failures per year divided by the number of units shipped per year

 

How do Brooks Instrument Mass Flow Controllers (MFCs) stack up?

With the largest installed base of thermal mass flow controllers and mass flow meters around the world, Brooks’ flow meters provide significant advantages in long term stability, response time, accuracy, repeatability, turndown, self-diagnostics and application flexibility.

Brooks Mass Flow Controllers and Mass Flow Meters offer:

  • Industry-leading long term stability ensuring consistent process results over the life of the device and a longer period between recalibrations
  • Self diagnostics and alarms minimize downtime
  • Multiple communication protocols allow easy integration into many control systems
  • Analog I/O devices allow for quick and easy system integration
  • Elastomer seal option provides good leak integrity and control valve shutoff dependability
  • Global approvals for a variety of service areas

Brooks Instrument mass flow devices have industry leading mean time between failure (MTBF) which provides the user with maximum up time. MTBF for several SLA Series mass flow controller models is shown below.

 

Model Description MTBF (years)
SLA5850 Mass Flow Controller 63
SLA5851 Mass Flow Controller 118
SLA5853 Mass Flow Controller 59

 

This MTBF information is based on actual shipments and warranty returns over a 1.5 year period. This period includes the infant mortality phase shown in the “bathtub curve” below and as a result likely underestimates the MTBF.

 

bathtub curve

The Bathtub Curve illustrates hypothetical failure rate versus time

 

If you have questions about MTBF or any Brooks Instrument products or services please contact one of our applications engineers or your local Brooks Instrument sales expert.

[1] W. Torell & V. Avelar; “Mean Time Between Failure: Explanation and Standards”; APC White paper #78.