Inline process refractometer
 |
Inline process refractometers are a type of refractometer designed for the continuous measurement of a fluid flowing through a pipe or inside a tank. These refractometers typically consist of a sensor, placed inline with the fluid flow, coupled to a control box. The control box usually provides a digital readout as well as 4-20 mA analog outputs and relay outputs for controlling pumps and valves. Instead of placing the sensor inline of the process, it can be placed in a bypass, attached by a thin tube.
This measurement has been an important element in the process control of the chemical and refining, pulp and paper, food, sugar and pharmaceutical industries for more than a century. For instance, the in-line concentration measurement can be used as a real-time predictive tool for the final concentration. A quick and accurate response is needed to optimize production. Cost reduction is possible by reducing the variation of mean average of the product concentration. The cost saving is related to the value of the component being measured.
A digital inline process refractometer sensor measures the refractive index and the temperature of the processing medium. The measurement is based on the refraction of light in the process medium, i.e. the critical angle of refraction using a light source. The measured refractive index and temperature of the process medium are sent to the control box. It calculates the concentration of the process liquid based on the refractive index and temperature, taking pre-defined process conditions into account. The output is typically a 4 to 20mA DC output or, increasingly, an Ethernet signal proportional to process solution concentration, liquid density, Brix or other scale that has been selected for the instrument.
About Refractometers Refractometers work because light travels at different velocities in different mediums, the light beam is bent at the interface between two adjoining materials. This is called “refraction”. There is an angle of light propagation at which refraction no longer occurs, the light beam instead being reflected back into the original material. This is called the critical angle. Critical angle is the result of light interfacing at two mediums. The Inline Process Refractometers measure this critical angle, thereby inferring the refractive index of the second material. Different materials have different refractive indices (RI’s), as do different concentrations. Critical angle is dependent upon these RI’s. It is equally important to note that the critical angle and refractive index are both closely related to the temperature of the liquid. The refractive index of a liquid at 20°C will be different from the refractive index of the same liquid, at the same concentration, when the liquid is heated to 90°C. Accurate temperatures for the process to be measured are therefore critical to an accurate measurement. How Refractometers Work Inside the refractometer's probe is the optical block. The optical block contains the key components of the Inline Process Refractometers. The key Refractometer Equipment components include the LED, prism, thermistor, and silicon detectors. During a measurement, the refractometer's LED shines through a sapphire prism. At the interface of the liquid and prism, some of the light is reflected back into the refractometer's probe, and some is refracted out into the liquid. The light that is reflected at the interface with the liquid meets the refractometer's two silicon detectors. These detectors are the reference cell and the measurement cell for the refractometer equipment. A third cell is also applied for “backscattered” light that is reflected back into the probe from suspended particles in the liquid being measured. It is the abilities of the Inline Process Refractometers to compensate for this “backscattered” light that give these refractometers the ability to monitor many liquids that would defeat other refractometers.
About DiGi Instruments Our Philosophy DiGi Instruments is founded on the understanding that many manufacturing and processing facilities need accurate, reliable and repeatable results from refractometer equipment - but they don't necessarily have to spend tens of thousands to get those results. Through a series of common sense approaches to the design and engineering of our products, DiGi Instruments offers its customers the best of both worlds; dependability and affordability. Yes, anyone can probably spend more on refractometer equipment, but for most of the companies that use this equipment it is costly overkill. The Principals When Dr. Barry Wilson, the company founder started DiGi Instruments in 1989, his vision was to build the best and most affordable In-Line Refractometers and In-Line Turbidity transmitters on the market. With extensive engineering experience in the areas of polarimetry, refractometry, consistency, concentricity, eddy current fault detection, ozone generation and UV monitoring and many awarded patents to his name, and having served as the Vice President of research and development of a successful instrumentation company, he assembled a talented team of engineers and technicians to successfully produce the best, yet the most affordable instruments on the market. DiGi Instruments has grown to become a leader in the field of refractometry and is ready to meet your most demanding needs. Fast Repsonse DiGi Instruments has earned a reputation for attentive service and problem solving capabilities that help our customers stay on schedule. We understand the importance of every component in your line and will do what is necessary to make sure your customized DiGiInstruments refractometer gets there when you need it.