The FP-25: Fast, Accurate, Reliable

by Shaina Shay

Alicat is proud to be part of the Halma family. Halma companies work to create a safer, cleaner, healthier future for everyone, every day. Alicat’s air monitoring products contribute to the environmental and public health component of this mission.

Saving the world, one calibration at a time

Our low-pressure drop Whisper mass flow meters are used by municipalities, cities, states, and countries to calibrate ambient air quality monitoring devices. Our mass flow meters are used to calibrate particulate monitoring (PM) machines, air sampling canisters, pesticide monitoring machines, and other analyzers. Calibration is important to ensure good data. Bad data can have political, legislative, and/or societal impacts. Because calibration takes time and skill, we worked with air quality technicians to specially design a product that is both compliant with the regulations of the Environmental Protection Agency (EPA) and meet the demands of air quality technicians.

The FP-25: Fast, Accurate, Reliable

The FP-25 is a highly precise, NIST-traceable device that can measure mass flow to an accuracy of +/-1% of reading. To make calibration faster and safer, there is a Bluetooth function which allows technicians to complete calibration from a distance. The device itself is built to be used in the field and can withstand being dropped from rooftops.

Learning from our Future Leaders

Alicat has been engaged in the air monitoring market for years, but we had the opportunity to view the FP-25 from a fresh perspective when Halma’s Future Leader Program came to visit. The Future Leaders program is comprised of intelligent, driven, and enthusiastic recent graduates. To encourage well-rounded growth, participants are exposed to a range of business related trainings through the program.

On May 17th 2019, 15 future leaders came to Tucson, Arizona to participate in a marketing training day at Alicat.

In just one day, future leaders paired off to develop a marketing content. The young leaders learned about Alicat’s history, products, and culture in the morning, and then had the afternoon to come-up with a plan.

We were astonished

Two teams took on the environmental market and focused on developing content tailored for the FP-25 product. The results were one full blown campaign plan and this video about why customers love the FP-25.

The proof is in the pudding

At the end of this day we were so impressed with the results. We never expected that there would be time to develop useable content, but we were wrong. This experience validated the how Halma is making their mission come true, by investing in people and companies that make things happen.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Accurate simplified testing for small volumes and differing configurations

 by Mic Chaudoir

Accurate simplified testing for small volumes and differing configurations 

A revolution in bioprocessing is underway in the form of single-use technologies.  Single-use offers the promise of lower costs, improved flexibility and shorter cycle times.  But what happens when a single-use bag or component fails ? It’s obvious that system integrity is critical for any bioprocess, but how can you know that your system is free of leaks before use ? Integrity testing can now be accomplished easily and quickly with an Alicat Scientific Whisper series mass flow meter or controller.

Fast and accurate leak checking can be a complicated process requiring a rather complex setup. When the Device Under Test (DUT) is subjected to a constant pressure within a closed system, any resulting flow is a direct measure of the leak rate. This test requires both stable pressure control at the DUT and accurate flow measurement to test for leakage. Leakages are most easily revealed and measured when the meter generates minimal pressure drop, the frictional resistance that the device introduces into the gas line.

For years, Alicat Scientific has provided a two-unit leak checking systems using a PC3-Series remote sensing pressure controller to maintain the required test pressure at the DUT and an M-Series mass flow meter to measure the leak rate.

More recently, Alicat has pioneered the simplified testing for leaks using a single Whisper series mass flow controller. This simplified process makes testing the myriad bags and containers used in single-use bioprocessing easier and more flexible. With full-scale pressure drops as low as 3.6 mbar (0.052 psid) and turned-down pressure drops as low as 0.018 mbar, the Whisper allows precise and responsive control with minimal frictional resistance.

For leak checking smaller test volumes, such as valves or sensors, a single MCW-Series mass flow controller that is set to control for pressure will maintain a constant pressure at the DUT while providing accurate mass and volumetric flow readings in real time. Configured this way, the Whisper serves the functions of both a pressure controller and a mass flow meter in one device. Alicat’s Whisper now makes leak checking for the small volumes needed for single-use technologies even faster…and simpler. This configuration also makes changing the configuration to test different devices, or testing infrequently, very achievable. From Alicat: The fastest flow controller company in the world.

Fast Leak Testing for Single-Use Bioprocessing

A revolution in bioprocessing is underway in the form of single-use technologies. But what happens when a single-use bag or component fails? How do you know that your bioprocessing is free from costly leaks or integrity failures? Leak testing of single use systems can now be accomplished easily and quickly with an Alicat Scientific Whisper series mass flow meter.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Using technology to reduce health and safety risks

 by Shaina Shay

Technological advancements have improved humans’ ability to monitor, assess, and protect societies from environmental health and safety hazards. When it comes to the air that we breathe, particulate matter (PM) monitoring machines are one piece of technology used to keep society safe by measuring the presence of potentially harmful particulates. The smaller the particulate in the air, the more likely that it can be absorbed into the body via the lungs.

The Environmental Protection Agency (EPA) regulates industry and enforces compliance based on the readings of PM monitors (epa.gov). Air standards have been established to minimize human exposure to particulate matter that may have adverse health effects.

To understand exposure over space and time, a national network of PM monitors has been established. These PM monitors are located in a variety of places, ranging from national parks, to suburban parks, to the skyscrapers in city centers.

The accuracy of data acquired through this network is critical because it could have legal, political or social impacts. To ensure good data, the flow, pressure, and temperature of PM monitors are calibrated on a regular basis.

Air quality technicians climb roofs, visit remote locations, and endure inclement weather to complete calibrations and document data.

Climb ladders 50% less with Bluetooth connectivity

Alicat believes that technology should reduce health and safety risks as well as increasing efficiency. That’s why we worked with air quality technicians to develop the FP-25 Flow Meter. Our FP-25BT with Bluetooth features reduce the number of trips technicians to on ladders by 50%.

Bluetooth connectivity also reduces your exposure to severe weather conditions. Even when ambient temperatures drop or humidity increases, these instruments provide fast and accurate measurements. Rain or shine the FP-25 has you covered.

If you’re in an industry that has you measuring flow in adverse environmental conditions, let us know. We strive to help the people who are helping our communities breathe clean air.

Ready to find out how we can help ?

Contact one of our applications engineers at 1.888.290.6060 or info@alicat.com to discuss your application.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Precise Mass Flow Enables Novel Pollution Sensing Technologies

Alicat Mass Flow provides accurate control of gasses under test

The growth of the IoT (Internet of Things) is driving the need for smaller and more ubiquitous sensors. Normally, one thinks of optical or electrical sensors in this context. This type of measurement has typically been in the province of automotive and process control industries and is largely unavailable at the consumer level. Presently, IoT is creating a need for low-power, low-cost gas sensors that can be utilized for consumer level applications. There are potential applications in the area of household air-quality monitoring, personalized healthcare, breath analysis and a multitude of other applications. However, existing sensors that could be used for these applications are generally not suitable due to large size, higher power demands and/or high cost. There are a number of competing technologies focused on providing sensors for this market; one of the most promising sensor types is the field-effect transistor (FET). In a recently published paper, Fahad et. al. describe a novel FET that promises to meet many of the requirements where existing sensors fall short. Many of the experiments described in the paper require highly accurate mass flow of measured gases – precisely provided by a set of Alicat mass flow controllers. 1

Fahad et. al. demonstrate a novel chemically-sensitive FET capable of detecting H2S as low as 10ppb. Sulfur Dioxide is an invisible gas that readily forms harmful compounds, including sulfuric acid and sulfate particles. Sulfur dioxide is a toxic air pollutant and is especially dangerous to asthma sufferers. The US, in particular, has made great strides in reducing sulfur emissions from powerplants. However, in excess of 500 million tons were still produced in 2011 from powerplants and other sources. 2 The same series of experiments showed detection of NO2 down to 1ppm levels.  Nitrogen Dioxide is another common air pollutant that can impact personal health.  NO2 reacts with other airborne substances to form particulate matter and ozone, both of which have significant negative effects on respiratory health.  The US EPA has recently tightened standards for NO2. These newer standards will require increased monitoring of ambient air levels to ensure compliance. Implementing these new standards will, in turn, require increased training and proper calibration of equipment used to ensure the required accuracy. Alicat makes a range of products specifically designed to help state and local environmental analysts and technicians ensure the needed levels of accuracy.3

These experiments demonstrate the efficacy of the novel low-power FET sensor. The experiments were conducted using known gasses from commercial suppliers; control of the gas input was critical to making accurate assessments of FET function. Alicat Scientific Mass Flow Controllers were used to ensure the accuracy of these measurements by precisely regulating the input flow of the gas mixture. The extremely high controllable range of Alicat’s mass flow meters allowed control of flow rates from 1-100 sccm. Our latest flow controllers boast an increased controllable range of up to 10,000:1, which can be helpful for any experiment where a range of flow rates is required.

As scientists and engineers continue to develop novel sensors to enable IoT technologies, precise, reliable mass flow will continue to be required. At Alicat, increasing the pace of scientific innovation is our greatest passion. All of our instruments are custom built to the needs of your science and ship in days, months.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicat Whisper Mass Flow Meters Lend Precision to Fiber Optic Process

by Ryan Barner

Fiber optic cables are highly desired for their speed of transmission and are growing as an industry. However, the industrial furnaces used for glass manufacturing require stable and repeatable control of gas for melt and annealing processes.

Preforms are the layered cylinders of glass, made on lathes using chemical deposition vapor flows, burners for heating and melting glass and pressure control to retain the shape while it is being formed. While the fiber drawing process means heating the end of a glass preform, and shaping the melting end into a cone that creates a continuous stream of molten glass which descends and cools into a fiber, which must then be guided in a way that will not break or alter it, while checking the thickness and adding layers to protect it.

Both require mass flow and pressure controllers that are fast, reliable and have high turndown ratios, all while functioning in potentially high temperature environments and compatibility with corrosive fuel gasses.

Industrial furnaces utilizing fuel gases for their burners exhibit low pressures.  Alicat Whisper series mass flow controllers offer a controllable range up to 1000 SLPM.  These flow rates can be achieved with a pressure drop across the Alicat MFC of as little as 1.65 PSI on our highest flow rate Whisper series controllers. This means even if the supply pressure is low, as fuel gases typically are, it is possible to control up to a full scale flow rate of 1000 SLPM.Alicat mass flow and pressure control instruments for glass and optical fiber manufacturing.

These low pressure instruments may also be deployed in annealing ovens and lehr ovens during the finishing process.  Using Alicat MFCs allow for control in each zone of the oven with repeatability and precision even if a low supply pressure is a requirement.  Ninety-eight gases and gas mixes are pre-programmed into an Alicat MFC providing options for variability in projects and processes.

Alicat MCW-series whisper mass flow controller, shown with optional backlit color display

In preform manufacturing, fiber drawing or ribbon forming processes – stable and fast mass flow and pressure control instruments not only ensure a better end product, but with Alicat devices, achieving these results is easier with our highly customized instruments and advice from Application Engineers.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicat Python and Python-driven command prompt

 by Bill Nick

Setup

Alicat Python and Python-driven command prompt (Windows Powershell) drivers have been developed principally by Pat Fuller at NuMat Technologies and are available for download from github.com: https://github.com/numat/alicat

In order to run the command prompt/Powershell driver, Python will first have to be installed on the computer. The latest stable Python 3 release is the recommended version to install: https://www.python.org/downloads/

Once Python has been installed, the simplest way to install the python/command prompt drivers is to command the following in the command prompt:

If the Python PIP package manager is installed and enabled, this is a simpler method:

Command Prompt (Powershell) Usage:

A menu of possible arguments and usage information within the command prompt can be accessed by entering “alicat –help” or “alicat -h”:

To poll an Alicat that is the only one connected to your target COM port, commanding only the port name will return data from the Alicat:

To poll a device with unit ID A, your command should look like this:

and the response from either of these commands should look similar to this:

Python Usage:

This command will open a serial connection to an Alicat device on the specified port:

If the Alicat is communicating on the specified port, it will return the same dictionary as when polled via Powershell.

Using this with Windows COM port COM1, for example, would look like this:

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Lowered Cost and Increased Speed for Biologics Production

 by Mic Chaudoir

With protocols for bioprocessing now firmly established, there is an increasing focus on reducing the cost of producing biologics, biosimilars, mABs and other modern medicines that require bioreactions. Producing these pharmaceuticals promises to revolutionize treatment of many difficult diseases, especially modern scourges that have been resistant to small molecule-based therapies. Focus on cost reduction and improved speed has centered on two promising developments: so-called “single use” bioreactors and “continuous” bioreactors.

Single use bioreactors lower costs by reducing the time and materials for sterilization and cleaning between production runs. In a conventional bioreactor, all material in contact with the bioreaction requires extensive and thorough cleaning and sterilization to prevent contamination. These processes in turn require extensive use of corrosion-resistant stainless steel and other resistant elastomers and materials. The extensive use of these costly materials is a major driver in construction cost for new facilities. Single use reactors, by contrast, use disposable bags to contain biomass during the reaction. Rather than sterilization, many of the components of these systems can simply be discarded in between runs, reducing initial material costs and time required in between batches. Alicat helps meet the challenge of these systems by offering fast, flexible mass flow control at an affordable price. Alicat’s COMPOSER “Gas Select” feature means that our modern high speed controllers can function for multiple gasses with ASTM traceable accuracy (including, Air, CO2, and Oxygen – over 100 in all). Controllers can then be moved between systems as needed, providing redundancy at lower price points. Additionally, single use reactors are often used to “scale-up” processes. The high turndown ratio of Alicat’s Mass flow controllers (up to 10:000 to 1 in some cases) mean that flows from a few sccm up to slpm ranges can be accommodated with the same mass flow controllers – allowing the mass flow control to scale with the reactor size.

Continuous bioreactors have been described as the “holy grail” of biologic production. These reactors are still a developing technology, but the promise can provide a bioreaction that allows for production over extended periods of time. Instead of typical reactions which are carried out for weeks to months – these bioreactors are designed to run for months to years. As with single use reactors, this would greatly reduce the cost per run. This is accomplished by dramatically extending the time of production between sterilizations. For this promise to be realized, homeostasis needs to be achieved by extremely accurate and responsive control of conditions within the reactor. Alicat can help overcome this challenge by providing extreme accuracy, responsiveness and control for your gas flow needs. Alicat’s controllers have an astonishing mass flow accuracy as low as .1% of full scale and unbeatable repeatability of +/- .02% of full scale readings. Additionally, Alicat supports a variety of protocols and connections to ensure compatibility with your preferences. A custom-built, high accuracy mass flow controller with this level of precision is typically available less than two weeks after ordering!

The speed of biologics development and bioprocess production continue to advance with lower costs, higher speeds and greater flexibility. Shouldn’t your mass flow controller be able to keep up ? Alicat – the world’s fastest flow control company.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicat Scientific attending BioAsia 2019

 by Mic Chaudoir

The BioAsia 2019 Life Sciences 4.0 Meeting is coming to Hyderabad, India from February 25-27 at the HICC. Alicat will be exhibiting our line of scientific flow control instrumentation at BioAsia for the first time inside the Scientific Enabler Pavilion

Alicat has recently announced our upgraded mass flow controllers with dramatic improvements in precision, response time and operating range. These newly upgraded units provide unmatched turndown ratios and incredible accuracy for low-mid range mass flow control. Alicat also has a full line of products for high flow rates, liquid flows, corrosive materials and other specialized flow control needs.

Alicat also shares BioAsia’s passion for Bioreactors. Alicat has a range of mass flow controllers suitable for bioreactor flow control and measurement. The innovative COMPOSER feature allows NIST-traceable accuracy of mass flow measurement under rapidly changing conditions. Other features of interest to bioprocessing engineers include a variety of protocols and connections to fit existing any format, as well as extremely large turndown ratios (exceeding 1,000:1) allowing for unprecedented scalability.

This will be the first time that Alicat has exhibited at this important conference. We’re happy to join the BioAsia community. Visit Booth # 38 and see what the fastest flow controller company in the world can do for you.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Customer needs translate to improved products

Andy Mangell

A guest blog from Andy Mangell. Andy is the sales director at Premier Control Technologies, a UK based process control technologies and products distributor which represents Alicat products. Andy has over 30 years of experience with pressure and flow control instrumentation. He can be reached at andymangell@pctflow.com.

Alicat Scientific’s standard product line is fast, versatile and tough. Their instruments make our customers’ jobs easier and more accurate, while reducing the number of instruments required. People love how easy they are to use and the short lead time between ordering and receiving the instrument. For both OEM producers and small research operations, Alicat’s ability to refine and customize instruments for their specific process is key to getting the best instrument to the customer. Listening to what customers need and anticipating improvements is how Alicat has been able to innovate and be the fastest mass flow controller company.

Since its foundation some 27 years ago, the concept of constant innovation and product development has been pivotal to the company’s remarkable success. Specifically, areas such as bi-directional mass flow measurement, precision pressure control within dead-ended non-flowing applications, multi-parameter measurement and control, true multi-gas capability and high turn-down have all benefited from the dedication to innovation.

Bi-directional mass flow measurement

By the application of either a positive or negative set-point signal, Alicat has enabled the possibility to control flows into a process in one direction first and then to switch into the opposite direction. Alternatively, flows can be controlled into a closed process and then vented without the need for additional bleed valves. Due to the inherently bidirectional nature of the Alicat sensor, the flow is measured in both directions and a net total provided if required.

Dual-valve precision pressure control

Precise control of pressure reduction and pressure relief valves from a single setpoint signal ensures process pressure remains stable, independent of other variables. Such processes as head space pressure control, glass reactor protection and the elimination of costly out-gassing through continuous bleed valves all benefit from this innovation. Alicat electronic pressure controllers provide responsive, stable control of absolute, gauge or differential pressures in dead-ended processes.

Multi-parameter measurement and control

Measurement of multiple parameters on the one instrument (mass flow, volumetric flow, temperature and pressure) enables the user to eliminate additional components within a system and the pipework/fittings required to install them, in addition to cables and electronic signal conditioning. All parameters are displayed on a single screen for easy monitoring of process gases or liquids. Any of the measurement parameters can be enlarged in the centre position for reading at further distances from the instrument. All of the displayed parameters are measured in real time, which allows you to look at the device display and quickly get an idea of how your process is operating. When a process begins to falter, this information can significantly reduce the amount of time it takes to diagnose and repair the failure. All Alicat mass flow controllers can be changed to pressure controllers or volumetric controllers via digital interface or via the display. The user can monitor mass flow while controlling pressure or vice versa.

True multi-gas capability

COMPOSER ™ gas mix composition software, available with color display

COMPOSER ™ gas mix composition firmware, shown on a color display

Following continuous innovation and development over the years, Alicat instruments are now preloaded with up to 130 full gas calibrations, thereby eliminating the additional measurement uncertainty introduced by conversion factors. Complete NIST REFPROP gas properties data has been loaded for each of the gases, ensuring that both the standard accuracy and optional high accuracy statements remain valid, regardless of the gas. The benefits to the user are significant. Instruments are no longer limited to just one application; once a certain project has been fulfilled, the MFC can be used again for a different project with different gases. Similarly, even within a single project, fewer instruments are required to meet the needs of multiple gases or multiple flow rates.

Wide turn-down range

Turn-down ratio is a measure of the usable range of an instrument, expressed as the full-scale range divided by the minimum point of measure. It indicates how much of the instrument range can produce accurate readings, which is very important when you want to measure or control a very wide flow range without having to change instruments. Most Alicat instruments have a turn-down of 200:1 as standard (i.e. as low down as 1/200th of the full scale), although with engineering collaboration and PD²I tuning this could be extended even further. As with multi-gas capability, the benefits are again significant: fewer instruments are required to cover a wide measured flow regime, and this results in cost savings for the user.

 

As a result of over two decades of development and innovation, a range of useful flow and pressure measurement and control devices has been established that, at their very core, have been designed to help the user make their life and work easier. This innovation will never stand still, and Alicat would welcome the opportunity to assist with any challenges you face and attempt to solve the impossible!

 

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Improving flow data with faster flow measurement

Our world is moving faster and flow processes are not immune to this. Newer industrial communications protocols can deliver flow data from hundreds of flow meters in less than a second. This increased speed of data acquisition can improve your process, but the speed of your flow sensor can improve the data itself. In this post, we’ll take a look at two examples of how Alicat’s sensor speed can make your flow data better.

Fast flow totalization of transient flow events at oil and natural gas wells

When you need to know the total amount of a gas that has flowed, instead of just the live flow rate, the measurement speed of your flow meter becomes much more critical. If your gas or liquid is already flowing, a flow totalizer can start and stop a timed measurement to take a sample of the total amount flowed during that time period. However, when you need to know the entire amount that has flowed from start to finish, significant amounts of your data can be lost as your flow meter comes up to speed. One of the more striking examples of this came through a research application with the US Environmental Protection Agency (EPA).

Alicat was contacted by an EPA researcher who needed to quantify how much gas was being emitted by pneumatic controllers at oil and natural gas well pads. At these sites, the natural gas that is already present is typically used to drive these controllers, and when they actuate some of the natural gas escapes into the atmosphere. The challenge was that most of these controllers were intermittent pneumatic controllers whose actuation periods lasted just a few seconds. A previous study had used thermal mass flow meters to totalize these emissions. However, the 1-3 second response rate of these meters meant that a significant proportion of the flow data was lost as the thermal flow meter tried to catch up with the transient flow rate.

In order to preserve the greatest amount of flow data, the EPA turned to Alicat’s pressure-based laminar flow meters. These instruments measure flow rates 1000 times each second and have a pneumatic measurement response time of 5 ms. With these flow meters installed, the researcher was able to follow the precise curve of the pneumatic controller’s actuation, from its explosive opening to its sudden shutting. The response speed of the sensor itself recorded much more of the available data compared to the thermal flow meter, making these measurements more accurate and reliable. The Alicat flow meter’s sensor speed was able to improve the quality of the data that the researchers obtained. You can read the resulting paper published in Earth and Environmental Sciences.

Improving the temporal resolution of flow readings for environmental monitoring and beyond

Another example of the benefits of fast flow measurement comes from the realm of ambient air monitoring. The gas analyzers that measure the concentrations of greenhouse gases in the air we breathe must be periodically calibrated to ensure they are measuring these small concentrations accurately. To do this, air monitoring technicians use dynamic dilution calibrators to generate known concentrations of the gas that the analyzer is designed to measure. Because this process is dynamic, the mass flow controllers inside these dilution calibrators must also be calibrated on a regular basis.

As gas analyzers have become more sensitive, the dilution calibrators have added mass flow controllers with lower flow rates, typically 10-20 sccm at the lowest, in order to simulate smaller gas concentrations. In the past, a positive-displacement (PD) flow meter was commonly used to calibrate these mass flow controllers. This type of flow meter provides an averaged flow rate that is calculated by dividing the total amount flowed by the duration of the measurement, but the very low flow rates required hid some critical data. At a flow rate of 20 sccm, such a flow meter takes about 20 seconds to complete a single measurement (see this video). At 1 sccm (the lowest point in the required 20-point calibration), the measurement time is more than 6 minutes.

When a mass flow controller failed its calibration, there was no indication of what was happening to the flow rate during the long measurement, because the only recorded data came at the end of the measurement. Perhaps the flow controller was oscillating on a regular cycle, or perhaps it started out well and then got clogged. Sometimes, the fault was that the PD meter got stuck in the middle of its measurement, but there was no way to diagnose this scenario without continuously observing the meter.

Air monitoring technicians in these situations have turned to Alicat’s fast flow meters to make visible the data that was hidden from the other flow meter. Because an Alicat responds pneumatically to changes in flow rates within 5-10 ms, the technicians are able to diagnose the cause of a failed calibration. When data is captured in real time, recurring oscillations that come from an underperforming mass flow controller are easily distinguished from a clog in the flow path. Indeed, when an Alicat is connected to a positive-displacement flow meter, it can diagnose failures that result when the puck of the PD meter stutters in its cylinder or when the puck takes too long to accelerate to match the speed of the flow.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com