Gas Chromatographers depend on Alicat
Chemical analysis with gas chromatography depends on stable and repeatable flow to achieve accurate analysis. For that, chromatography instrument manufacturers—and labs—rely on responsive, precision instruments for gas and liquid handling at numerous locations in the process, both to control flow and pressure, and to calibrate flow into and through the chromatograph.
In part because of our custom engineering for each application, chromatographers get more stable flows—which achieve better accuracy—while reducing the number of parts and components needed to regulate their process through our multivariate technology.
A mercury, PCB, and organic compound testing company:
Not many other units can deal with low pressure differential. “So far the mass flow controller is doing exactly what I need. It actually has more features than I need but…I find them useful.
“I should also mention the help given to me by your sales engineer Michael Owen. He was knowledgeable and professional. He responded quickly to my requests with pertinent information.”
Chromatograph OEMs have relied on Alicat’s flow and pressure control instruments for over 25 years: one of our very first custom-built instruments was for a gas chromatograph.
One customer, a chromatograph manufacturer, found that Alicat EPC electronic pressure controllers and BASIS mass flow controllers could meet their stringent repeatability and high resolution needs in the temperature ranges of their GC ovens. With the high performance of these easily integrated devices, their process gas chromatographs perform with an accuracy and repeatability which was formerly only available in Lab gas chromatographs.
Other chromatography manufacturers and chromatograph component suppliers depend on mass flow controllers from Alicat to handle gas flows in permeation devices. Permeation devices can be used as trace gas sources. For these applications, Alicat OEM BASIS MFCs are sometimes chosen to provide high turndown ratios, gas selection capability and precision in a compact device.
In the Chromatography Lab
In the lab, users often tell us that the flexibility of the Alicat instruments in being calibrated for many gases is a very helpful capability. They appreciate having:
- High turndown ratios, meaning fewer instruments are needed, reducing spares cost
- The relief of easy-to-use-right-out-of-the-box simplicity
- A portable meter that can be used throughout the lab without finding outlets or running cables
- Accuracy and repeatability are basic requirements, always
For users of chromatographs and spectrometers, Alicat meters are often used for calibrating and confirming flow. Occasionally, when performance improvements or a change in function are desired, Alicat flow controllers or pressure controllers are retrofitted into existing systems.
For calibration and process control requirements, metering of flow over a fixed time, at the carrier flow between the source and the injector, or at the column exit or at the split vent, especially for GC’s that don’t have built-in gas flow meters. Alicat meters measure mass flow, but also report volumetric flow and gauge pressure—a handy multivariate metrology tool.
To set up a custom sample injection system, using pressure or flow control, Alicat devices might be integrated into that injector control.
In troubleshooting situations, some users verify flow after the column and before the detector (whether FID or spectrograph).
A Petrochemical Inspector, testing flow into the detector:
“The greatest feature of this mass flow meter is the multigas calibration…Great product!”
Choosing the right instrument
Depending on your need, and the step in your chromatography process, here’s a list of instruments to consider.
Creating trace gas mixes:
- MFCs like our MC Series mass flow controllers
For building into OEM gas mixing manifolds:
Carrier gas flow control or pressure regulation
Control system pressure while measuring mass flow
- Set an MFC to use a pressure control loop: measure mass flow while reducing complexity.
Measuring the mass out of the vent
- Totalizers help you calculate total mass into or out of the system, efficiently.
Integration into automated systems
- PLC and industrial integration with any of several industrial protocols (EtherNet/IP, DeviceNet or others) means test stands can be scaled to work as stand-alone capital equipment or integrated into a lab’s control and reporting scheme.
Questions about flow or pressure control in chromatography?
MC Standard Series Mass Flow Controller
Alicat’s special ability to control on the pressure loop settings means you can control pressure in the system while measuring mass flow.
Chromatography customers choose Alicat MFCs for:
- Carrier gas flow control
- Trace gas mixing
- Controlling system pressure while measuring mass flow, using a “control on backpressure” setting
BASIS OEM Gas Flow Controllers
BASIS™ mass flow controllers offer high accuracy and excellent turndown in a compact unit. For high-volume projects, it provides repeatable, reliable control in an economical gas flow control component package. Designed for stress-free integration within original equipment manufacturer (OEM) products, BASIS features a small footprint, high-accuracy MEMS sensor and Alicat’s leading fast valve control.
PC Standard Flowing Volume Series
PC Specs Pressure Controller page
Electronic Pressure Controllers
EPC and EPCD electronic pressure regulators are highly customizable for easy integration within original equipment manufacturer (OEM) products. EPC/EPCD deliver high accuracy and fast, droop-free closed-loop control in compact, competitively-priced packages.
MB and PCU Portable Calibration Series
Integrated rechargeable lithium-ion batteries make for laboratory-grade flow verification that you can take with you anywhere—across the lab, or out to the instrument shed. For low pressure-drop applications, where pressure differential is preserved as much as possible, customize as “Whisper” (MWB). For corrosion-resistance, select MBS portable mass flow calibrators.
Alicat’s Portable Calibration Unit (PCU) houses three mass flow meters in a single battery-powered case for the widest possible calibration range. Click for more information about portable meters and calibrators.
Chromatography labs and equipment manufacturers use portable meters for:
- Calibrating and verifying flow rates with reliable, data-rich logging and high accuracy
- Flexibly metering a large selection of 98+ changing gases without recalibration or K-factors!
- Fewer meters per bench: high turndown ratios means fewer device changes
- Calibration goes fast with 1000 samples per second averaging
- Custody transfer of gases, using data logging
Where and how to use an Alicat flow meter to check your chromatograph
Mass measurements, volumetric measurements and pressure measurements all come from one Alicat mass flow meter. It can be used from front to back to provide insight into and improve the performance of your chromatograph.
Download the PDF white paper: In-House Check of Chromatograph Operation
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