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

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

Flow and pressure control tailored for you

Highly customized flow and pressure control for demanding applications

You know your process. We know the parts you need to help get you there.

An Alicat PC-15PSIG-D pressure controller

At Alicat, we are not only focused on accuracy but customizability. We give our customers the best solution for their application, whether that be in a humid, corrosive or heavily regulated environment. Every Alicat pressure, liquid or mass flow controller is completely tailored to the customer’s needs, from flow rates to communication protocols.

Alicat devices are as diverse as the applications they are used in. For example, one customer needed to control pressure in a test environment to adjust humidity. They purchased this device: PC-15PSIG-D/5P, 5IN; a 15 PSIG pressure controller. For many customers, this level of customization is enough to satisfy the application needs.

However, some customers need more.

A customer called us looking for a pressure controller that could control gas at 155 PSIG and handle flow up to 5,000 SLPM. The controller needed to be placed in an OEM box system but not lose interactivity from outside of the box. Within the box, the system was set to operate at temperatures up to 70 oC, and to be consistent with the rest of the equipment the device required analog signals and connections.

They also expressed some concerns to us: the system included pressure sensitive instruments which would break above 155 PSIG. Since the supply pressure was 180 PSIG this would damage or break the instruments, so the controller needed to measure pressure precisely at these sensitive instruments to ensure the pressure limit was not exceeded. While the operating temperature was 70 oC, the storage temperature of the box dropped down to -50 oC making condensation a big concern. With previous Alicat devices they’ve purchased, they noticed that the devices retained the last setpoint in its memory at power up, which was a security concern.

The instrument we designed for this customer addresses all of these concerns and is represented by the part number below:

PCRH3-100PSIG-RD-REMOTE-M12-40×55-SAE24-CC/CP, 5IN, RANGE (155 PSIG), P1: 180 PSIG, FLOW (5000 SLPM), GT[1], PUSP: 0, RD: 1.5’, REM: 1’

Now, this might look a lot like alphabet soup, but every letter and number lets us know exactly what this Alicat will look like.

Alicat PCRH3-100PSIG-RD-REMOTE high flow pressure controller with remote sense port and panel-mounting

Let’s walk through the part number:

High-flow pressure control: PCRH…40×55…P1: 180 PSIG, FLOW (5000 SLPM)

The first letters, simply put, designate that the device is a pressure controller, shown as PC. The RH afterwards means that this device has a pair of Rolamite valves in Hammerhead configuration. This allows for 5,000 SLPM high flow capacity. Hammerhead valves open and close simultaneously which doubles the surface area of the valve orifices, allowing more flow. Additionally, we built the valves with a custom size of 40×55, 40 being the orifice size (0.040”) and 55 being the number of holes in the Rolamite hole pattern. This specific hole pattern was determined to afford the greatest control across the expected range of inlet pressures (P1: 180 PSIG) and desired maximum flow rate (FLOW: 5000 SLPM).

Remote pressure sensing: 3

The customer wanted to maintain pressure after a delicate system of other instruments, but needed to regulate the airflow before it reached this system. The 3 signifies a remote sense port, which allows such pressure controllers to sense flow in a different area than where the valves are controlling the flow. This system is ideal in applications with limited space because the valve does not need to be located where pressure is being measured.

Customized pressure range: 100 PSIG…RANGE (155 PSIG)

The maximum pressure that the customer intended to control was 155 PSIG, so we modified the sensor range from the 0-100 PSIG stock sensor range to 0-155 PSIG.

Designed for panel-mounting: RD-REMOTE…RD: 1.5’, REM: 1’

This pressure control system was located inside of a box, but needed to be controlled from the outside. A remote display, noted as RD, allows the display to be mounted outside of the box, giving user access to all of the functions inside. RD: 1.5’ is the length of the cable that connects the remote display to the rest of the controller. The remote display was tested to withstand temperatures down to -50 oC, the lowest anticipated storage temperature.

With operating temperatures within the boxed system as hot as 70 oC, a REMOTE electronics package was specified. In high temperature scenarios which would damage the standard electronics, we separate the sensor assembly from the rest of the electronics package, so only the sensor interacts with high temperatures and the electronics are kept safe. REM: 1’ is the custom length of the cabling needed to connect the electronics to the sensor and flow body of the device.

Locking industrial connector: M12

The customer requested a locking M12 electrical connector to keep their system from coming unplugged inside the box.

Coated to protect against condensation: CC

Moving from the -50 oC storage temperature to room temperature would sometimes lead to condensation within the system, and this could short out the electronics. To prevent this, we added a protective conformal coating (CC) on the circuit board to protect against any condensation.

SAE24 fittings

The customer was already using SAE24 threaded process connections, so we matched it.

Mismatched analog signals: CP, 5IN

Another customization for this device is a mismatched analog input and output: a 4-20 mA output pressure data (CP) and a 0-5 Vdc setpoint input signal (5IN). Typically customers use an input and output that match, but this customer needed a mismatched setup to make this pressure controller work with their existing system signals, including a PLC that has an output of 0-5Vdc.

Remote analog tare: GT[1]

Because the customer was not using a digital interface for communications with the PLC, they needed a way to remotely tare the controller using analog signals. To satisfy this need, we designed this device to be tared by grounding Pin 1 of the M12 connector.

Preconfigured setpoint: PUSP: 0

To avoid revealing potentially sensitive information, this pressure controller will always bring up a setpoint of 0 PSIG (PUSP: 0).

 

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

Tough environments call for tougher instruments

Alicat instruments are built specifically for the conditions under which they will operate and the environments where they will be used, according to each customer’s needs. We work directly with customers to understand the stressors that will be placed on the instrument to ensure that every Alicat is up to the challenges they may experience in the field, lab or factory. Because the best repair is the one you never need, Alicat has a number of options to keep your process flowing smoothly.

In a precision test setting, it is unlikely that errant particulates, changes in ambient conditions or back flow of water will ever reach instrumentation. But Alicat instruments are often used far from the clean room. They are used to calibrate air monitors where the weather is a factor. They are used to maintain pressure and control gas mixtures in bioreactors, where cleaning means running the risk of splashing instruments. Some processes require the use of gases far more aggressive than air and other such nonreactive gases.

Humidity

In ambient air monitoring applications, humidified air can make it difficult to achieve the required accuracy in the field, especially when it is hot and humid. That is why we developed the FP-25. This flow meter incorporates a live humidity sensor that ensures accuracy of measurement at any temperature and humidity.

Recently we worked with an air monitoring customer who needed to control the flow of ambient air in humid areas at a high level of accuracy. We developed a flow controller that uses the same internal relative humidity sensor and software to correct readings based on relative humidity that we use in the FP-25. This allows for accurate sampling of ambient air as temperature and humidity change.

Water

Water outside the process line can cause issues as well. While some solutions might include creating some sort of protective box around process control instrumentation, or simply placing a plastic bag over the equipment and hoping for the best, we can build units to be rated up to IP66. Because our gas flow bodies are the same as our liquid flow bodies, a little water in the system won’t cause complete failure of the device, provided that it can be dried out later. Additionally, we have a conformal coating option to protect the interior electronics for situations where changes in temperature can cause condensation. Rain, back splash from a hose or conditions that might lead to condensation on or within the instrument are non-issues for Alicat instruments equipped with these options.

And if water or other damaging conditions are anticipated to a point where the electronics are at risk of damage greater than what can be protected with an IP66 rating or coating, we can build the device with the sensor and the electronics package as a separate remote option. This option is most frequently used in high heat environments, but can efficiently remove the more sensitive electronics away from wet conditions.

Corrosive Gases

Some processes throw more at the device than the forces of Mother Nature, and not all gases are as gentle as air, nitrogen or other common gases. Many customer processes require corrosive gases like ammonia or sulfur dioxide that could cause damage to the instrument. Depending on the gas being used, we can use FFKM or EPDM elastomers and stainless steel components. For some applications, we can customize from there, too. Our S series instruments are built with 316L stainless steel sensors, and in many cases the flow bodies and valving can also be ordered as 316L.

Hazardous Environments

For processes and environments that are potentially explosive, most Alicat instruments can be built with a CSA Class 1 Division 2/ATEX Zone 2 area certification. These instruments can be used in oil and gas applications where exposure to combustible gases is possible.

Your process can be messy, rough, jarring and abrasive. The last thing you want to worry about is your process control instrumentation being too delicate to handle the task. That’s why at Alicat we custom-build each unit with the customer’s process in mind. These Alicats are not just built to withstand tough process conditions; they can be configured to thrive in harsh ambient conditions as well. Backed by annual recalibrations and our limited lifetime warranty, an Alicat instrument will keep your process running smoothly, even in challenging environments, for years to come.

Your process, your project and the end results are what are most important. Spend your time on the things that matter, not worrying about your instrumentation.

 

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

Totalizer Averaging Smooths Out the Data in Flow Measurements

Posted by: Alyssa Jenkins

Alicat’s optional totalizer feature is a great way to meter the total flow through a system. Adding a totalizer to a controller means you can dispense fluids in set quantities. We call it batch mode: set a total mass desired, set a flow rate, and the controller stops when the delivery amount is reached.

Totalizer averaging adds another number to your totalizer screen—the average flow rate during the metered period.  Calculating the average after the sample has finished is simple, but real time averaging can be tedious and require additional programming.  Why not just have it on the screen?  Not only does totalizer averaging appear in the screen, it also appears in the serial data stream—right next to the totalizer value. Now you can easily streamline your existing communication programs.

tot-avg-screen_highlighted_800

Totalizer averaging can be extremely helpful during leak checking or flow characterization.  Using a mass flow device to control the pressure on a device under test and while measuring the flow rate is a compact solution essentially including two devices in one.  For smaller flow rates and volumes, minute changes in pressure will force changes in flow rates—which in turn change the pressure.  This can lead to an oscillation of both pressure and flow rate.  While the oscillation is natural, it can make it difficult to determine a single number to report.  With totalizer averaging, the average flow rate can easily be seen and recorded in real time rather than waiting until the process is complete to calculate.

Alicat devices have always had a flow averaging feature available to help minimize noise, since we sample in milliseconds. For users who are unaccustomed to a fast-responding sensor, the totalizer averaging can be easier to read, and helps to correlate our flow measurements to results from slower-responding instruments.  Totalizer averaging gives the ability to average flow measurement data over variable periods—from milliseconds to hours—extending the possibilities.

If the totalizer software is already on your device, the totalizer averaging feature can be added easily in the field via serial communication.  For those who are familiar with serial communication, simply add 1024 to the current number in register 88.  (Need a little help getting set up for serial communication?  Our applications engineers can help you out). The totalizer option itself is described on the product options page.

Here’s a video that shows how easy it is to use the Totalizer Options:

The totalizer option and totalizer averaging can be added to most Alicat mass flow and liquid devices ordered since 2003. Contact our applications engineers for more information about how to upgrade your unit today—get your serial numbers handy.

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

Faster Flow Calibration for Gas Analyzer Audits

Posted by: Danielle Adams

Alicat’s “Whisper” series portable flow meters reduce the time it takes to conduct flow calibrations and audits of gas analyzers and gas dilution calibrators used in ambient air monitoring and other applications.

Auditing Gas Analyzers and Gas Dilution Calibrators

Gas analyzers and a pair of gas dilution calibrators in a typical ambient air monitoring shed. Alicat Whisper flow calibrator pictured at bottom left.

Gas analyzers and gas dilution calibrators in a typical ambient air monitoring shed. Alicat Whisper flow calibrator pictured at bottom left.

Flow calibrating a gas analyzer can consume your entire day. Most dreaded are low flow calibrations, which can take an hour or two alone. You watch the bubble or piston slowly rise to the top of the positive displacement tube at a pace of 10 sccm over the course of several minutes, and cheer when it finally reaches the top. Do that another nine times for a single averaged data point, unless the bubble sticks or the piston stutters along the way. There must be a better way.

Every analyzer technician knows that maintaining a constant sample gas flow rate is critical to ensuring the measurement accuracy of the analyzer. Gas analyzers are used in ambient air monitoring to identify the concentrations of greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) that are found in the air around us. Process analyzers are used to monitor the concentrations of such gases in smokestack emissions. Unfortunately, the flow controllers that are built into these analyzers often do not live up to our expectations, and this necessitates the use of regular flow check, calibration and audit cycles to ensure the quality of the data.

Gas dilution calibrator, showing its program of calibration flow rates.

Gas dilution calibrator, showing its program of calibration flow rates.

Analyzer flow rates can be checked and calibrated directly using high-accuracy flow meters. When it comes to testing the compositional analyses of the gas analyzers, gas dilution calibrators are used, which themselves use two or three mass flow controllers to control the composition of their outlet gas streams. Gas dilution calibrators combine a large flow rate of unpolluted air with a smaller flow rate of the greenhouse gas being analyzed, for example CO2, to provide the CO2 gas analyzer with a sample of the pollutant gas at the desired concentration.The presence of flow controllers within these dilution calibrators again requires the use of high-accuracy flow meters to ensure their correct operation.

Faster Flow Calibration with Laminar Differential Pressure

Calibrations and audits of gas analyzer and dilution calibrator flow controllers have often been performed using positive displacement flow meters. “Wet” positive displacement flow meters measure the time it takes for air bubbles to pass through a tube coated in a soapy solution. “Dry” positive displacement meters measure the time it takes for air to push a piston up a tube. In both cases, a single flow measurement data point can take as little as a few seconds up to many minutes to complete, depending on the flow rate. Calibrating all the analyzers in an ambient air monitoring shed can easily take a full day with these slow measurement methods.

Alicat Whisper-series portable mass flow meter.

Alicat Whisper-series portable mass flow meter.

Alicat Scientific’s “Whisper” series flow meters measure extremely low differential pressure through a laminar flow element to present live readings of both actual volumetric flow and standardized mass flow. Flow readings are calculated a thousand times each second (1000 Hz), so even the lowest flow rates are visible instantly. Streaming and recording this data over RS-232 can reveal cyclical flow inconsistencies and help identify underperforming mass flow controllers. The wide flow ranges of Alicat’s NIST-traceable mass flow meters (200:1, or 0.5% to 100% of full scale) means you can calibrate analyzer mass flow controllers down to the bottoms of their ranges with confidence in the accuracy of their calibration. Using a Whisper, calibrations at the bottom of a mass flow controller’s flow range take just seconds instead of hours to obtain a robust average of flow measurements. Portable Whispers (MWB series) integrate a rechargeable battery for even greater convenience and efficiency while you are conducting your flow audits.

Whisper-series mass flow meters are available in common analyzer flow controller ranges of 20 slpm, 10 slpm, 200 sccm, 100 sccm and 5 sccm, or any other range of your choosing between 0.5 sccm and 1000 slpm. These flow meters are also well-suited to other applications, including:

  • Auditing the flow rates of indoor air sampling instruments used in industrial hygiene applications,
  • Setting the mechanical flow controllers used with air sampling canisters, and
  • Calibrating the flow controllers used in gas chromatographs and other analytical instruments.

Explore the Whisper product page to learn more about these fast flow meters.

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