Process refractometers

A refractometer uses light to measure liquid concentration. An LED sends the light into a sapphire or balf prism. The prism is in contact with the liquid and the light from the LED is reflected back from the liquid surface like a mirror. The angle of the reflected light will change depending upon the liquid concentration. This reflected angle is called the angle of refraction. A refractometer uses a CCD to capture the returned light from the liquid. A shadow will be cast on the CCD and this shadow will move based on the angle of refraction. A refractometer uses the output from the CCD to precisely calculate the liquid concentration based upon the CCD image.

In line refractometers use this same principle as a refractometer mentioned above in How does a refractometer work. The difference is an inline refractometer making this analysis of the CCD image constantly and updating many times per second to give a real time reading of the process liquid conditions. Typically inline refractometers are used for process monitoring and process control so they need to be extremely fast to react to process variations.

All refractometers operate on the same principle, but there are many different versions of refractometers from basic to very sophisticated. A user would select the type needed based on the application, accuracy and budget they have for a refractometer. There are very simple hand held refractometers that are purley held up to the light and using the eye the reading is taken, these are typically low cost and low accuracy and affected by human error. The next level would be a small hand held digital refractometer where the determination of the refractive index is calculated electronically, these come in low, medium and high accuracy and will vary in cost accordingly. There are laboratory and at line refractometers for bench top use and these also come in various accuracies and will be selected based on the application and accuracy needed. Inline refractometers would be the last refractometer type and these will monitor a process continuously, these also have various types and brands and should be selected based on the accuracy required and application.

The term inline process is used when a measurement of a product is required to be done during the manufacturing process. This product could be a liquid or also me a solid material as there are alo technologies to measure solid materials inline. In the case of a refractometer, inline process analysis means analysing the concentration of a liquid during the manufacturing process. This becomes especially important if the manufacturer wants to improve quality or increase yield from the liquid.

An example of this would be coffee liqueur where the coffee is a very expensive ingredient, if the coffee liquor can be monitored in real time during evaporation or mixing the liquid concentration can be controlled very precisely. This allows the manufacturer to be assured the quality is consistent and they can manufacture the product within specification, but also not make the liquid with a higher amount of coffee than necessary. With inline process control the product yield is increased by controlling coffee addition and not putting more coffee than water.

In-line refractometers can be used for many applications. Refractometers can measure any binary solution and its concentration. Applications vary widely and different refractometer models and accessories may be needed depending on the application. The range of applications covered is vast and if you have a specific requirement please contact one of our experts to discuss your requirements further [email protected]

A Process refractometer is mounted in the process via a mounting fitting or flange, these allow the refractometer to be mounted in a process pipeline , tank or vessel. The refractometer will then shine a light beam into the process usually from an LED. This light is then reflected back into the refractometer at a critical angle. This critical angle of refraction of the returned light is captured on a CCD detector. From the CCD image the refractometers' electronics can convert this signal into a measurement of the liquid concentration or Brix (% Sugar).

An Inline process refractometer is typically mounted into the production line using a ferrule, spool or mounting fitting. These inline connections come in various types from tri-clamp sanitary to Varivent and flanged connections with various flange patterns. The Inline fitting is usually welded or connected to mating flanges at the position where the most representative reading of the process can take place. The Inline refractometer is then inserted into the fitting and it will measure by sending a light beam into the process medium and measuring the angle or refraction of the returned light onto a CCD detector. From the CCD the liquid concentration or Brix (%Sugar) can be determined

Yes these devices have different names but are esentially the same type of device. Brix is a term used in industry for % sugar concentration 1 degree Brix is 1 gram of sugar in a 100 gram solution. A refractometer is very simple to operate and the most accurate way of measuring sugar or brix concentration in a liquid.