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Single instrument for reactor gas dosing

Published: 6 September 2016 - Sarah Mead

Alicat Scientific Mass Flow Controllers offer multiple parameter control and reporting in a single instrument; mass flow, volumetric flow, pressure and temperature are simultaneously visible via the on-board display and each have their individual output signal via the electronics interfaces.

Perhaps more important, however, is the capability for the user to select and change their preferred control method for a particular experiment or application. Not only can the instrument control on flow (mass or volumetric) whilst measuring and outputting the pressure but, by means of the front panel interface, the instrument can be instantly changed to control on pressure whilst measuring and reporting the flow.

To achieve the same, other solutions on the market require a combination of several more instruments, with the complication of convoluted wiring leading back to a control panel, PC or lap-top. Not only is such a solution relatively expensive and time consuming to configure, but it is also fixed in its control mode and more limited in its capability.  Traditional methods might include manual pressure regulators and mechanical flow measurement devices, but these are affected by changing ambient conditions, require constant vigilance, and provide no data-logging capability.

Alicat Scientific has been successfully designing and manufacturing precision instruments for over 25 years and this success can be attributed not only to industry-acclaimed instruments but also the company’s core ethos of providing affordable complete solutions to complex control and measurement problems. Alicat understands that there are seldom “off the shelf” solutions to a dilemma, an important stance which ensures that they are always willing to customize their core products to perfectly fit any given application. The unique design and measuring technologies of Alicat flow and pressure control products allows their instruments to be used in applications where competing devices may not have the flexibility or durability to survive.

Alicat’s technological advantages can be seen within the following application example. Reaction vessels require the addition of gases under a controlled pressure regime within such industries as chemical, pharmaceutical and biotechnology, to name but three. Multiple gas species are common-place, across a wide flow regime, with accuracy and precision often being important – especially for characterization within research and development. Rapid control response and accuracy across a broad range of gases is often critical to a successful process.

Standard features of the Alicat product line are of great assistance to this application.

· A standard turn-down ratio of 200:1 ensures that the wide flow regime can be covered by just one instrument. Depending upon the application, an even wider turn-down is possible.

· A lowest flow rate measurement capability of 0.0025 mln/min ensures that all gas added is accounted for – especially towards the end of the reaction.

· With up to 130 gas calibrations stored on-board, the direct selection of different gases maintains accuracy, reduces inventory and eliminates the issues caused by conversion factors employed by other technologies.

· Fast control response of between 30- and 100-ms from sensing a change to settling, ensures stability and high precision.

· The ultra-low pressure drop available across the instrument eliminates disturbance of the process regime—especially within low pressure systems.

· Standard solutions, which eliminate pressure overshoot, maintain highly stable conditions for the precise control of dead-ended, non through-flow systems.

· Additional software packages are available for programmable pressure profiling and batch control.

Scripted programming is available as part of the Flow Vision™ software package. The control software’s graphical user interface (GUI) provides automatic configuration; session saving for easy reloads of configuration and experiment setup; data capture, logging and graphing; and script building for automating command sequences.

All told, single-instrument measurement and control of flow and pressure are available within open flow and dead-ended systems for applications across a whole host of process industries, research, and development. These standard instruments employ time-proven, unique technology advantages to reduce cost, improve yield and save time within gas dosing and/or batching processes.

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