Superior Products

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 PR-111 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 PR-111 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 PR-111 Inline Process Refractometers to compensate for this “backscattered” light that give these refractometers the ability to monitor many liquids that would defeat other refractometers.

What are your Requirements?

If your manufacturing or testing procedures call for the measurement of a few parts per million, you may need to invest more than you would with the PR-111 Inline Process Refractometer. But if, like the vast majority of companies that use refractometers, your equipment readings need to be accurate and repeatable to within +/- 1% of span, you’re in luck! We specialize in manufacturing equipment that performs consistently and provides accurate results within the ranges you specify. Not more, not less. Please visit the Contact Us section of this site, and tell us your tolerances and requirements. We’ll customize a cost efficient and effective PR-111 Inline Process Refractometer system that will provide a solution for your specific needs. Get the right equipment system for your job, and literally save thousands.

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