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Into the Danger Zone
Approval for Hazardous Area
Bronkhorst Cori-Tech announces the release of a new option for its mini CORI-FLOW™ series mass flow meters for low flow rates. The compact flow meters, operating via the Coriolis principle, are now available with IECEx and ATEX approval II 2G Ex d IIC T6 for use in Zone 1 hazardous areas.
The instrument is built into a rugged enclosure with separated compartment for the electronics. The flow meters, suitable for both liquid and gas flow applications, cover flow rates from 0.1 g/h to 30 kg/h and can be used in systems with pipeline pressures up to 2000 psi.
The unique design of the miniature Coriolis sensor features superior response time and high accuracy, irrespective of changing operating conditions with regard to pressure,temperature, density, conductivity and viscosity.
Mini CORI-FLOW™ mass flow meters offer integrated PID control for close-coupled control valves or pumps, thus constituting compact Coriolis mass flow control loops. The instruments offer both analog and RS-232 communication, optional fieldbus interfaces and additional functions such as alarms, totalizer (to measure fluid consumption) and batch dosing. The mass flow meters feature fluid temperature and density as secondary digital outputs. As an option, the Coriolis flow meter can be equipped with a heater to prevent condensation or solidification inside the instrument.
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Out of the Normal Zone
Supercritical CO2
Supercritical carbon dioxide refers to carbon dioxide that is in a fluid state while also being at or above both its critical temperature and pressure, yielding rather uncommon properties. Carbon dioxide usually behaves as a gas in air at STP or as a solid called dry ice when frozen. If the temperature and pressure are both increased from STP to be at or above the critical point for carbon dioxide, it can adopt properties midway between a gas and a liquid. More specifically, it behaves as a supercritical fluid above its critical temperature (31.1 °C) and critical pressure (72.9 atm/7.39 MPa), expanding to fill its container like a gas but with a density like that of a liquid. Supercritical CO2 is becoming an important commercial and industrial solvent due to its role in chemical extraction in addition to its low toxicity and environmental impact. The relatively low temperature of the process and the stability of CO2 also allows most compounds to be extracted with little damage or denaturing.
Supercritical carbon dioxide is seen as a promising green solvent because it is non-toxic, and a byproduct of other industrial processes. Furthermore, separation of the reaction components from the starting material is much simpler than with traditional organic solvents.
Areas of application for supercritical CO2 include silicon wafer cleaning, medical device cleaning, nano and micro particle formation, solvent extraction, dyeing of textiles, and foaming of polymers among a growing list of others.
 
Bronkhorst has experience working with this unique fluid with both the mini CORI-FLOW™ and CORI-FLOW instruments (as well as our pressure controllers and flow control valves) having been successfully tested in customer applications.
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SELECT Your Instrument
EL-FLOW® Offering Covers Wide Range
The EL-FLOW® Select family of gas mass flow meters and controller instruments offer greater flexibility for user selection of both flow ranges and gas types while maintaining their high accuracy with turndown ranges for measurement and control up to 187.5 to 1.
As a result of this feature, Original Equipment Manufacturers are able to drastically reduce the variety of spare instruments they keep in stock and thus reduce the cost of ownership.
Users of MFC's in pilot plants or laboratories can rescale their instruments on site, saving time and money; substantial costs for mounting and dismounting and also for service and recalibration are no longer applicable!
For the convenience of the user, Bronkhorst High-Tech has developed a free and easy-to-use software tool called "FlowTune".
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Good to Know
Turndown Ratio
Turndown ratio is also commonly referred to as rangeability. It indicates the range in which a flow meter or controller can accurately measure the fluid. In other words, it's simply the high end of a measurement range compared to the low end, expressed in a ratio and is calculated using a simple formula.
Turndown Ratio = maximum flow / minimum flow
For example, if a given flow meter has a 50:1 turndown ratio the flow meter is capable of accurately measuring down to 1/50th of the maximum flow. So, suppose a flow meter has a full scale rating of 20 l/min the flow meter will measure down to 0.4 l/min of flow.
Keep in mind that the maximum and minimum flow capability of a meter or controller is likely to be a greater span than the measurable and controllable range. For example, a mass flow controller with a 50:1 turndown ratio may have the capability of measuring as high as 25 ln/min or as low as 0.16 ln/min but the turndown ratio will govern the actual measurable range. In this example if the calibrated high flow is 25 ln/min, then the lowest that can be measured is 0.5 ln/min (1/50th of 25). If the application requires that the calibrated minimum flow is 0.1 ln/min, then the maximum flow that can be measured is 5 ln/min (50 times 0.1).
A mental image of this concept may be to picture a set of 100 stairs (the overall minimum and maximum flow of an MFC), and a length of carpet that will only cover 50 stairs (turndown ratio). You can cover (measure) any 50 of the 100 stairs, but you can not stretch the carpet to cover more than 50.
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