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.


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
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Gas Chromatography’s mobile phase and mass flow control

Posted by: Joe Ancona

It’s safe to say that a Gas Chromatograph is one of the most important tools one will see in an analytical chemistry laboratory. Chromatographs are the workhorses of the analytical trade. When it comes to separating, analyzing, verifying purity, or determining concentrations of various chemical concoctions, the “GC” as it is commonly known, can provide a quick, accurate, and repeatable result for a large cross-section of known compounds. Of course, to have precision in analyzing means all the components in the system must work as expected. A clean ‘column,’ appropriate for the substances being separated, a properly prepared sample, diligent injection methodology, and a stable mass flow rate of the inert carrier gas are all required.

Basically, a modern gas chromatograph is designed to take a sample in the form of a ‘slug’ and pass it through a long ‘column’, as carried by a steady flow of inert gas. While the sample moves through the column in a computer-controlled oven, it’s heated to various temperatures, and its output is fed to the detector array. The sample and carrier gas are eventually vented out as waste.

The key measurement function of the GC is centered on timing. As the components of the sample are separated in the column, they emerge at different times and in rising and then falling intensities. The detector simply plots the peaks against time (retention Rt) and strength (peak area). Based on known chemistry, the components and concentrations of the original sample can be determined with amazing accuracy.

Misnomers and misconceptions

If you’re unfamiliar with how a gas chromatograph works, let’s dispel a couple of misnomers and incongruities. First, there is no traditional vertical ‘column’ inside the GC! (The decades old classic ‘column chromatography’ process does in fact use an actual glass tube, up to several feet tall. The column effects the purification of individual chemicals through a powder or slurry, using the principals of partition equilibrium.) Although the over-arching concepts are very similar, the modern GC’s column is now a very thin, coiled capillary tube. These fine quartz or fused silica tubes have only 0.1 to 0.53 millimeter internal diameters, but are cut to 12 to 100 meters in overall length! Modern capillary tube columns are internally coated with a thermally stable, high molecular weight polymer. This extremely thin polymer layer (0.1 – 10 thousandths of a millimeter) is referred to as the ‘Stationary Phase’.

A second common misconception comes from the word “Chromatography” itself. When you see ‘Chroma’ you might think ‘color’. When you see ‘-graphy’ you would normally assume there is some type of written or printed result. Just as the ‘column’ sub-component name has carried over from traditional separation techniques, so has the ‘chroma’ element. In the early days of thin layer chromatography (circa 1900), it was the actual colors of the various compounds in plant materials spread across the paper stationary phase which gave the Chromatography process its name.

Lastly, there isn’t a universal gas chromatograph for every compound. Some aspects of the sample to be tested must be known in advance, so that the right kind of GC is used. Different chemical groups need different columns, tailored to their properties. Certain volatile compounds need to be vaporized, and kept that way, meaning oven heating schedules must be selected for the best separation resolution. Most importantly, there are many different types of detector heads to match the appropriate selectivity of the test sample. Detector technologies include flame ionization, thermal conductivity, electron capture, photo-ionization, conductive, and so on… A majority of the detection technologies are dependent on steady state mass flow rates.

Timing is everything

As the various chemical compounds move through the capillary via the flow of inert gas—called the Mobile Phase—each will effectively ‘stick’ to the walls of the column at varying levels of adhesion and therefore will elute through the tube and into the detector head at different times. This happens regardless of the steady flow rate of the carrier gas, since the compounds all have a unique—and therefore identifiable—affinity to the stationary phase coating inside the capillary. All of the compounds make it through eventually; but it’s how fast they make it through that distinguishes one from another. Because of this, it is imperative for the carrier gas flow rate to be constant; otherwise flow rate would become a seriously disruptive variable to the detection of a particular chemical compound.

Imagine a sturdy wooden ramp in your backyard, used to roll different types of balls across a freshly cut patch of grass. Starting at the top of the ramp, a bowling ball rolls down, and across the yard. It’s barely slowed by the friction of the grass. A Bocce ball has a similar result, but doesn’t quite make it as far as the bowling ball. A soccer ball falls someplace in between the two. A whiffle ball hardly goes a few feet past the end of the ramp, and a ping pong ball is stopped within inches. Obviously, each ball has its own mass, diameter, angular momentum, rolling resistance, etc., but within reason, one could determine which ball is which, just by how far it rolled on the grass; once the norms were established. This assumes of course that the uniform grass surface (think: polymer coating in column) isn’t swapped out for a rocky dirt lot (a contaminated column), and that the fixed wooden ramp (a.k.a. the steady carrier gas flow rate) isn’t raised or lowered randomly during testing (unstable gas flow).

Minimizing the Variability of Flow

The effectiveness of a gas chromatograph relies heavily on stability and repeatability. Whether it be the method of injection of the sample, the computer controlled oven temperature profile, the use of a clean ‘blank’ (just ask any DUI lawyer about that one!), or the steady state flow of the carrier gas, the only variable in the process should be the sample itself.

Alicat Scientific, Inc. specializes in both precision mass flow control and high speed/high accuracy pressure control; each of which can be used to deliver exacting inert gas flows to your GC column. Even in low flow regimes, our mass flow controllers can provide stable flow from zero to full scale within tens of milliseconds. Each MFC has the ability to measure and control up to 98 default (common) gases and gas blends; changeable on-screen, or via digital control. No matter what inert carrier is being used for a particular test (N2, He, Ar, CO2), you can use the same Alicat MFC for each, so long as it is set to the gas being flowed.

If the GC uses a fixed orifice that requires stable pressure control, Alicat produces a wide range of electronic pressure controllers (both standard and OEM electronic pressure regulators) which can be custom tailored to just about any flow rate/pressure condition/speed, achieving the best result possible.

For verifying flows in a particular gas chromatography system, or to calibrate the gas delivery components within a GC, use one of our portable calibration flow meters to quickly establish proper carrier gas operation:

Our flow measurement technology has been used and trusted for over 25 years by some of the leading gas chromatograph manufacturers in the world.

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
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7v Firmware Update Makes Interface More Intuitive for Alicat Flow and Pressure Instruments

Posted by: Danielle Adams

We’ve just made it easier to use your Alicat mass flow meters and pressure controllers from their front panels. This post has all the details on our 7v firmware update, which features a more intuitive user interface.

If you’ve been with Alicat for very long, you’ve seen us add new menu selections to our flow and pressure instruments from time to time. We incorporated these features into a set of “Miscellaneous” menus (MISC1 and MISC2) in order to preserve the existing interface. However, after filling up MISC1 and MISC2 with new functions, we decided it was time to give the entire menu system an intuitive update.

Alicat mass flow controller showing new basic configuration menu

Alicat mass flow controller showing new basic configuration menu

Here to explain the motive behind these changes is Brian Clandenon, Alicat’s Senior Software Engineer:

“As Alicat has added more functionality to our instruments, the idea was to make minimal changes to existing buttons in the menus. While this was reasonable for each small change, so many changes built up over the past few years that some related functions became scattered across multiple menus. This made the menus more challenging to navigate and to remember.

Alicat mass flow controller showing new advanced setup menu

Alicat mass flow controller showing new advanced setup menu

One goal of a good menu system is to make settings easy to find, so it became time to review the overall structure of the menus. We endeavored to organize the settings in ways that would be more intuitive to new and existing users alike, so that the changes would outweigh the inconvenience of learning the new locations.”

The following FAQ describes the changes to Alicat’s menu structure in the new 7v firmware.

Which instruments are affected by this change?

All Alicat-branded instruments manufactured on or after May 22, 2017, will ship with 7v firmware, with the exception of no-change customers who have not yet approved this update.

Can I update my existing instruments to 7v?

Alicat’s 7v firmware update is compatible with most Alicat instruments that have serial numbers of 135,000 or higher. Some instruments with serial numbers between 80,000 and 135,000 may also be compatible with 7v. Upon request, we can update your firmware to 7v during your instrument’s next annual recalibration at no charge. Alternatively, we can update instruments outside of the recalibration process for a firmware update bench fee of $80 (USD).

Will my new 7v Alicat communicate the same as my existing 6v Alicats?

Yes. Communications protocols and commands have not changed in the move from 6v to 7v, so your command set will remain the same, no matter which protocol you have been using.

Which changes will I notice?

Alicat mass flow controller showing new main menu

Alicat mass flow controller showing new main menu

The new menu map is reproduced on the following page. Below, you will find a listing of changes to the menu structure. Please see your new operating manual for more details.

  • A new BASIC CONFIG menu allows easy access to GAS SELECT, DEVICE UNITS and STP/NTP options. The GAS menu option also displays the currently selected gas.
  • A new TARES menu gives you access to flow and pressure tares, plus AUTO TARE.
  • A new ABOUT menu collects DEVICE INFO, DEVICE STATE and MFG INFO in one place.
  • The contents of the old MISC, MISC1 and MISC2 menus can now be accessed via the ADV SETUP menu, with the exception of STP/NTP, which is now in BASIC CONFIG.
Feature New Menu Location (7v Firmware) Old Menu Location (6v, 5v or 4v)

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
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The RS-232 Communication Protocol and your Alicat instrument

Posted by: Joe Ancona

The 55-year-old RS-232 protocol is the default method of talking to Alicat devices. Aside from RS-232, you could configure your instrument with RS-485, Profibus DPV1, ModBus RTU, DeviceNet, and Ethernet IP protocols. For the bulk of our customers however, the tried and true RS-232C communication standard will remain the go-to method for commanding and reading Alicat devices.

The Not-So-Standard RS-232 Standard

One of the main reasons that RS-232 has survived for over five decades is that it is a useful, but low level and rudimentary signal, with fairly loose operational guidelines. In 1962, the sole application for the RS-232 communication standard was connecting electromechanical typewriters and their host mainframes/modems, commonly known as ‘Teletype’ systems.

When more advanced electronic machines were developed subsequently, proprietary adaptations led to nonstandard pin assignments, connectors and signal voltage levels. For example the original specification called for a DB-25 connector, but in the last 30 years most RS-232 products have adopted a DB-9 connector (technically called DE-9M).

The ‘data’ being sent on RS232 lines are simply positive (+) and negative (-) voltage pulses relative to a ground reference. A group of +/- pulses sent by one device are carefully timed by the receiving device and decoded into whatever the hardware settings deem to be data bit packages. In other words, the RS-232 standard only defines a relatively loose general electrical framework to transmit and receive electrical pulses. What one does with all these pulses is ultimately up to the connected hardware. Things like character encoding, spacing, start bits, stop bits, bit order, error detection, bit transmission rate, etc. are not the responsibility of the RS-232 scope, and are established by the user’s connected circuitry, usually in the form of a serial communication port and its associated chips and transistors.


It’s the COM Port’s job to make sense of the pulses on behalf of the attached computer or peripheral. For reference, an RS-232 system must transmit from one device (sent on its Tx pin), to a receiving device (received on its Rx pin), and vice-versa. Do not try to connect Tx to Tx or Rx to Rx in an RS-232 three wire system! The only pin that is connected directly is the ground pin, which gives both ends a common reference point to measure the pulses from. Each RS-232 driver uses inversion logic and employs a single ended, bi-polar output voltage to feed to a UART (Universal Asynchronous Receiver/Transmitter). Because the system has three wires and two distinct channels of communication, it is considered a “Full Duplex” system. Data can be transmitted at the same time as it is being received.

RS-232, the Alicat Way

Understanding how loose the RS232 “standard” really is, you might be wondering how Alicat uses it. Alicat does offer the ubiquitous DB-9 or the “standard” DB-25 connector, but we can provide RS232 communication on any connector that is offered, such as DB-15, 6 pin industrial locking connectors, and of course the default 8 pin miniDIN jack.

Alicat RS-232 Specifications

However, our real departure from the standard, is how Alicat has exploited signal levels and allowed for multiple units to work on the same COM Port. Because Alicat devices neither accept nor produce negative voltages, a traditional +/- 15V RS232 is not possible. Fortunately, a positive only pulse of +5V can be made to replicate an RS232 waveform (logic high ‘mark vs. logic low ‘space’), readable by 99% of all UARTs used today.

Once UART serial ports went out of fashion in the early 2000’s, USB to serial converters took their place; most today use the FTDI chipset to replicate the COM Port. Alicat’s unique signal profile is also fully compatible with these devices.

In addition to bending the rules for signal level and polarity, Alicat has also designed a clever work-around for being able to use up to 26 units at once on a single serial COM Port. The technical term for this capability is called ‘Multi-Drop’ communication, and is supported by all Alicat units equipped with serial communication (whether RS-232, or the differential signal based RS-485). Through multi-drop communication, every device on the line is configured to have a unique identifying letter (A-Z), and every unit listens to the commands that have been sent. However, even though each device ‘listens’ to each command, a particular unit will only accept and respond to the command if the instruction begins with that instrument’s unique ID letter.

So you can read the current flow rate on unit “A”, give a new setpoint to the MFC “B”, and reset the totalizer on unit “C”; all while being hooked together on the same three wires (electrically in parallel).

Even though the RS-232 communication ‘standard’ itself is old enough for a place at the Smithsonian Institution, it is still heavily used today for all types of computer based systems that talk to various peripheral components. Employing the universal ASCII (American Standard Code for Information Interchange) character set as our language, Alicat instruments will continue to be sold with the robust, universal, and reliable RS-232 system for the foreseeable future. For basic connection and terminal examples please see our video and instructional here:

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
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Customer Experience: Ethernet/IP

Posted by: Michael Hodges-Owen

Most customers don’t call us for our razor-sharp wit, or our slightly eccentric social skills. Instead, we know with certainty that whenever a customer comes to us, they have a problem that needs to be solved. While Ethernet/IP™ is not required for every process, some customers insisted on it. We recently added Ethernet/IP to the list of available communication protocols that can be configured on any mass flow, liquid, or pressure device. We wondered what the most significant benefit was for choosing it. So we reached out to a few companies who have already implemented it into their process to find out why they chose this option.

For perspective, consider that most Alicat devices are configured with an analog input/output connection. The connection requires individual signal wiring for each unit, which can get messy if there are a lot, and it only provides information on one or two parameters in the process. Our instruments are also normally configured with RS-232 (or RS-485) connections–those require reliable drivers, written for the specific, proprietary formats with which you’re communicating. It was important to one of our customers to acquire near real-time process information for control and diagnosis, to include setpoint, mass flow, volumetric flow, absolute pressure, temperature, and valve position. Using Ethernet/IP, which supports 10 and 100 Mbps bandwidths, gave them the capability to talk to multiple Alicat units over a redundant network that was easy to implement into their process.


Not only did the Ethernet/IP option fulfill their requirements, the versatile configuration options clinched their decision to go with Alicat. Most standard features–such as the multivariate front panel display, or selection from 98+ gases with full accuracy–come with Ethernet/IP equipped devices too. However, the devices don’t have an analog output, or support Power over Ethernet (PoE). The units are equipped with two RJ45 connectors to provide the redundancy that is expected within an automated control system. Alicat’s Ethernet/IP has been certified in conformance by ODVA®, the standards body for Ethernet/IP.

Ethernet/IP is rapidly growing in popularity.


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
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Custom Part Number Decoder

Posted by: Edgar Schrock

Because Alicat instruments are so highly customized, our part numbers get quite long and confusing. Customers often want to reorder a similar instrument or to find out what options are included in a particular one so they can repurpose it. The part number, printed on the silver manufacturer’s label on flow body of your Alicat instrument can tell you a remarkably large amount about what the factory settings were when we shipped it.

Senior Applications Engineer Mike Owen has put together a very concise way of decoding the settings and options embedded in your part number. It’s a one-page PDF you can find in our site navigation menus under accessories or support. Just look for the “Part Number Decoder” link.

An unexpected benefit of the decoder is that you can use it as a quick reference on whether or not we offer an option as a standard addition. If you don’t see the option you need, you should still contact us, because custom engineering solutions are a big part of what we do, every day.

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
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3 reasons why Alicat is the fastest flow controller company in the world

Posted by: Jas Gill

Building the fastest mass flow meters/controllers and pressure equipment in the world is both a point of pride for us and a unique factor for which our customers select Alicat instruments. The question is, ‘fastest’ in regards to what? Having started working at Alicat Scientific recently, I’ve found these three things which help make Alicat the fastest flow controller company in the world.

Reason #1. Fast Sensor Response Times

Alicat devices have the fastest response time compared to any other flow device manufacturer. The frequency of sampling means the sensor takes close to one thousand readings in a single second. Through a PID loop, which regulates responsiveness, a valve then controls the flow rate to the set point. The control response time for valves is 50-100 milliseconds–adjustable through PID tuning. If we apply the chemical kinetics analogy to this system, the rate determining step (RDS) or the rate limiting step would be the valve adjusting its position according to the difference between the set point and the flow reading. The sensor itself is very fast, detecting changes in pressure every millisecond. Thermal sensors, which are relying on the absorption and transmission of heat information, take longer to detect flow changes—it’s physics. This is one reason why our patented laminar flow differential pressure mass flow devices are quicker than thermal flow devices.

More about control speed of response

Reason #2. Me! (Also known as) Fast Technical Support

We don’t have separate phone extensions for technical support and new applications. You won’t have to wait to be put through to the right department, everybody is available immediately.
When you call us to specify a product or to troubleshoot your flow process, one of our applications engineers—like me—helps you with technical queries, troubleshooting or applications. Virtually every instrument we ship is customized in some way to the customer’s application, and our application engineers help you do that.
When you send in an email (be it new orders, service requests or general inquiries) to us, we try to respond within an hour—we’re even opening international service offices and coming in early to cover more time zones around the world.
With Alicat, you can expect the fastest customer service.

3. Convenient features that make you faster

Alicat devices have a built-in Gas Select feature that’s different from all the others. Many other brands offer gas changing on the instrument, but with some big drawbacks: you suffer from reduced accuracy, and you may need to calculate and program in K-factors to your process. For customers who are unable to accept reduced accuracy, the actual result is weeks of delay while the instrument is recalibrated at the factory, or down time while an instrument is replaced from spares.
Alicat devices change gases without losing calibrated accuracy, and they do it ultra-fast, at the touch of a button. The standard line of mass flow controllers have 98 different gas calibrations, the stainless steel MS/MCS series devices have 131 calibrations, including corrosive gases. Using Alicat devices gives you the flexibility of instantly repurposing an instrument for a different gas without delays in reconfiguration.

There are certainly other ways in which Alicat is fast. What’s your favorite?


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
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Alicat Adds Industrial Automation Protocols to Vacuum Flow Control Instruments

Posted by: Edgar Schrock

EtherNet/IP and DeviceNet options integrate mass flow instruments into coating and sputtering process control

Alicat Scientific has expanded the communications protocol offerings on its line of mass flow controllers for vacuum coating applications, adding EtherNet/IP and DeviceNet. Alicat’s MCE-Series and MCV-Series mass flow controllers ensure the optimal coating environment in vacuum chambers, maintaining product integrity in vacuum deposition.
The Alicat MCE and MCV accurately control gas flow rates as low as 0-0.5 sccm full scale or as high as 0-20 slpm full scale and capable of 20 to 50 millisecond control response times.
MCE controllers for vacuum with ethernet/IP protocol
The Alicat MCE and MCV accurately control gas flow rates as low as 0-0.5 sccm full scale or as high as 0-20 slpm full scale and capable of 20 to 50 millisecond control response times.

The new industrial automation protocols enable real time data–including mass flow, volumetric flow, absolute pressure and temperature, with full temperature and pressure compensation– to be read centrally by the PLC and used to manage the MCE- and MCV-Series instruments. Users may change setpoint or gas selection, and issue other commands to Alicat instruments using a DeviceNet or EtherNet/IP enabled PLC or computer.

The Alicat MCE and MCV accurately control gas flow rates as low as 0-0.5 sccm full scale or as high as 0-20 slpm full scale and capable of 20 to 50 millisecond control response times. Fast response times can greatly improve vacuum coating end products and help eliminate target poisoning. The integrated pneumatic shut-off valve is normally closed, affording positive shut-off of 1 x 10^9 atm-sccm/sec Helium max.

In addition to the new EtherNet/IP and DeviceNet protocols, Alicat offers Modbus-RTU and PROFIBUS communication options. The MCE-Series and MCV-Series may be used to replace legacy and discontinued MKS instruments. Made to fit the same space as common industry mass flow controllers, both series are easy to integrate into existing systems. All Alicat instruments are backed by NIST-traceable calibration, comprehensive technical support and a lifetime warranty.

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: Website:

Remote Control of Alicat Instruments with Flow Vision SC

Posted by: Rick Patton

Flow Vision™ SC

Flow Vision SC is Alicat’s Windows® desktop application for controlling and logging data of our flow and pressure control devices. It is versatile and intuitive, with many capabilities—which you might also say about our instruments. It is separate from the COMPOSER™ and Gas Select™ firmware built into our main product lines, Flow Vision apps expand and complement the built-in firmware.

The graphical user interface (GUI) of Flow Vision SC allows for actions as simple as polling or displaying the Alicat’s measurements, or as involved as running complex scripts involving changing setpoints of, and datalogging from, Alicat devices. You can save these scripts for future use, graph your results, and log your data for later review.

Flow Vision SC is capable of:

  • Remote setpoint and control loop commands
  • PID control loop tuning
  • Automatic configuration—automatically senses instrument’s type and current parameters
  • Session saving for easy configuration and experiment setup reloads
  • Data capturing and logging into common file formats
  • Graphing tool to see states and changes over time of instruments
  • Simple and advanced script building for automating meter and control command sequences
  • Software alarms
  • Serial terminal interface for direct commands, polling and data frame feeds
  • Communicates with up to 26 devices—gas and liquid flow controllers, meters and pressure controllers

Flow Vision logging data

Flow Vision SC data logging options

Getting up and running

Connecting your Alicat device to a PC, and communicating with it through Flow Vision SC:

  • Connect a serial cable to the RS-232 port on the device. RS-232 is the default serial connector installed on our instruments. RS-485 connections can also be ordered.
  • Connect the other end of the serial cable directly to the computer through a USB port, using an Alicat serial cable.
    • You can get help identifying COM ports on your computer with this video.
    • You can get drivers for serial communications cables here.
    • Not enough COM ports available? Use a BB9 breakout box, explained in the next section of this article.
  • Start the Flow Vision SC software
  • Load the instrument(s) into the software through the Devices tab – choosing a designation and selecting the proper COM port for each – and you’re ready to start communicating with your device.

Adding multiple Alicat devices

Your PC might not have enough physical ports to connect all the Alicat devices you have in your process. In that case, a BB9 multi-drop breakout box will connect 9 devices to a single COM port. You can communicate with up to 26 devices on a single copy of Flow Vision SC, by daisy-chaining BB9 boxes.

Try before you buy

Want to try out Flow Vision SC before you buy? Contact Alicat for a 30-day trial key, and download the software on the page for  Flow Vision SC software. A different application, Flow Vision MX, is a gas mixing program, and has a very different set of features.

More remote communications options

If Flow Vision SC software doesn’t suit your need for remote communications, consider:

  • PLC: Alicat devices can be ordered with PLC communication protocols (Ethernet/IP, DeviceNet, Modbus or PROFIBUS) and a choice of connector protocols.
  • Analog inputs and outputs: Nearly all Alicat devices (flow meters, flow controllers and pressure controllers) have built-in analog and digital communications modes—so you can choose which to use, when you want to.
  • On-board display and input buttons: Our main lines of MFCs, meters, and pressure controllers come with onboard LCD displays and input buttons for navigating the menus. It’s a convenient way to get an instrument up and running quickly without remote communications. Many users like to see what is going on at the instrument, even if remote communications are the ultimate plan.

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
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Creating a flow standard for harsh environmental conditions

Creating a flow standard for harsh environmental conditions

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How ambient air monitoring technicians helped craft the FP-25

Breathe in the crisp, frigid air. Feel the snow blowing against your face. Such weather would push most flow standards well beyond their limits of accuracy. Not so for the FP-25. It was tailor-made for these very conditions, thanks to technicians just like you.

Alicat FP-25 flow calibrating a Thermo Scientific Partisol 2000 FRM air sampler

Alicat FP-25 flow calibrating a Thermo Scientific Partisol 2000 FRM air sampler

This is the story of how ambient air monitoring technicians helped craft the FP-25, Alicat’s new weatherproof flow standard for outdoor air samplers. This instrument is the product of an iterative process that was centered upon continuous user feedback. We simply built what air monitoring technicians told us what they wanted, plus a little bit more.

The story begins with air monitoring technicians who were already using Alicat’s portable mass flow meters inside their shelters. These technicians had become frustrated with the lengthy 20-point calibration process for the mass flow controllers inside their gas dilution calibrators. Replacing their positive displacement meters with Alicats reduced their flow calibration times at each point to just a few seconds, even at 5 sccm.

"Whisper" portable mass flow calibrator, shown with optional color display

“Whisper” portable mass flow calibrator

After Alicat released the Whisper series of low pressure drop flow meters, some of these technicians began to apply this new technology to calibrating their outdoor ambient air samplers. Outdoor flow measurement is no easy task for a high-precision, laboratory-based flow standard. So, we got to work figuring out how to maintain our laboratory-grade accuracy under the harsh environmental conditions that these technicians faced.

Reducing temperature equilibration time

Alicat FP-25 flow calibrating a Thermo Scientific 2025i FRM air sampler

Alicat FP-25 flow calibrating a Thermo Scientific 2025i FRM air sampler

Technicians who used our lab-based Whisper flow meters told us that they took a long time to equilibrate to ambient temperatures outside, especially on sunny days. Big blocks of stainless steel with embedded temperature sensors worked well in the lab, but not so much outdoors. We switched out the steel for aluminum and reduced the size of the block, but we still had to contend with the issue of radiated heat.

The solution to reducing equilibration time started with lowering the temperature sensor deeper into the flow path. This made it more accurate in measuring the precise air temperature, even if was artifically elevated due to radiant heating by the sun. Then we added a fast-responding external temperature probe that the FP-25 uses to correct the internal flow stream temperature to ambient conditions. Together, this setup means that you can start using your flow standard more quickly and keep using it under direct sunlight on a hot day. Even coming out of a heated vehicle into sub-zero ambient temperature requires just a few minutes for equilibration.

Maintaining flow accuracy below zero

Air monitoring happens year-round, so technicians in the northern US and Canada perform outdoor flow calibrations at temperatures as low as -30°C. These subzero conditions wreak havoc on electronic instruments, reducing battery life, obscuring LCD screens and making o-rings brittle. At temperatures below freezing, the pistons of positive displacement meters freeze up, rendering them unusable. In the case of Venturis, their pressure sensors become less responsive, which makes their response less predictable, and so they become less accurate.

The problem of maintaining accuracy below zero was a tough one. Electronic pressure sensors tend to undergo changes at subzero temperatures that result in altered electrical responses to the physical deformations of the sensor. Alicat’s engineers devised a creative solution to this well-understood problem. We subject the pressure sensors of every FP-25 to the full range of operational temperature, from -30°C to +60°C, monitoring their response at multiple points along the way. The resulting response curve is unique to each instrument and becomes part of its final flow and pressure calibration. On account of this advanced process, our FP-25 has the most accurate flow calibration available on an Alicat instrument. At any temperature within its wide operating range, your FP-25 will be accurate to better than 1% of reading.

Combating wind and dust…and snowflakes

Alicat FP-25 flow calibrating a Met One BAM 1020/1022 FEM air sampler

Alicat FP-25 flow calibrating a Met One BAM 1020/1022 FEM air sampler

Some air monitoring technicians have reported that wind can be a significant problem during flow calibrations. They noted that even a snowflake can cause their Venturis to choke. Because volumetric flow standards typically feature minimal pressure drop, so as not to influence the volumetric flow readings, they are also quite sensitive to wind. Indeed, the Alicat Whisper flow meter that is sitting on my desk as I write this reveals the presence of airflow when my office air conditioner kicks on. Although this sensitivity makes the instrument more accurate, it can also make flow measurement more difficult when the wind blows. Windy days can also send dust, or snowflakes, through your flow standard.

To resolve this issue, we took a cue from the manufacturers of air samplers, who long ago figured out the solution to wind and dust. Air sampler inlets incorporate screens to filter out large dust particles, and their louvered designs prevent windy conditions from influencing the flow rate within their downtubes. The Alicat FP-25 takes full advantage of these features of the sampler inlet when it is mounted in line with the air sampler’s downtube, a configuration we call Direct Mode. In this configuration, the FP-25 is positioned immediately below the PM10 inlet, but above the PM2.5 very sharp cut cyclone (VSCC), if used. This affords the flow sensor full protection from wind, dust, rain and snowflakes, and it enables the FP-25 to monitor the very same flow conditions that the sampler sees under normal operation.

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