Portable refractometer LH-B55
3*AAA(About 2000 times test)
Dimension and weight
1. Zero setting:
Perform Zero Setting prior to using the refractometer.
The temperature of the distilled water used for zero-setting should be the same as the ambient temperature. If not, let the water temperature to adjust to the prism temperature before pressing the “CAL” key to zero set.
2. Measuring items:
Press “TEMP” key to measure temperature;
(2) “RI” or “BRIX”
The refractometer can measure “RI” and “BRIX”, to switch both parameter, pressing “TEMP” key and holding, then pressing “MEAS” key, you will find the top of LCD changes between “RI” and “BRIX”.
Note: “RI” means refractive index.
3. Replacing batteries:
There is a signal at the right top corner of the screen to show the remaining power of the battery. “” means enough power; “” means the low voltage and battery needs to be replaced. Details as below:
(1)Remove the screws by screwdriver from battery compartment cover, do not break the protective pad located underside of the cover;
(2)Properly insert the batteries, noting the positive and negative poles.
(3)After inserting the batteries, place the protective tape the battery compartment cover, then tight the screws.
Principle of operation
Most operate on the same general critical angle principle as a traditional handheld refractometer. The difference is that light from an LED light source is focused on the underside or a prism element. When a liquid sample is applied to the measuring surface of the prism, some of the light is transmitted through the solution and lost, while the remaining light is reflected onto a linear array of photodiodes creating a shadow line. The refractive index is directly related to the position of the shadow line on the photodiodes. Once the position of the shadow line has been automatically determined by the instrument, the internal software will correlate the position to refractive index, or to another unit of measure related to refractive index, and display a digital readout on an LCD or LED scale.
The more elements there are in the photodiode array, the more precise the readings will be, and the easier it will be to obtain readings for emulsions and other difficult-to-read fluids that form fuzzy shadow lines.
Digital handheld refractometers are generally more precise than traditional handheld refractometers, but less precise than most benchtop refractometers. They also may require a slightly larger amount of sample to read from since the sample is not spread thinly against the prism.
The result may be displayed in one of various units of measuremeant: Brix, freezing point, boiling point, concentration, etc. Nearly all digital refractometers feature Automatic Temperature Compensation (for Brix at least).