The Hand Held Refractometers - Coolant 0-18 are optical instruments which can quickly measure the concentration of aqueous solutions using the principle of the critical angle of refraction, and thus by a very simple operation deter.
Check a sample of water which has been left to stand for a period in the room (the water temperature should be the same as the room temperature) regardless of the measuring temperature. Set the boundary line to zero by using the adjusting screw knob for calibration. Then measure the sample and note the scale reading which can be taken as the true concentration value. Variations in room temperature may can an error, so it is recommended that the zero-setting be checked at intervals of 20 minutes using the test water above. Other ranges available such as 0-18 please enquire. Points to remember in use: •Hold the refractometer between thumb and forefinger of the left hand and use the right hand for adjusting the eyepiece and manipulating the sample. Do not hold the refractometer by enveloping the entire tube with the palm of the left hand. •When the sample is severely turbid or coloured, the field of vision darkens and the boundary line may become unclear or completely disappear. In such cases, it would be effective to use direct sunlight or bright light from the lighting equipment for a microscope. •Since the refractometer is an optical instrument, do not drop it or handle roughly. •Since the prism has a relatively soft surface, be careful not to scratch it. •After use, clean the prism surface and daylight plate with a soft cloth soaked in water and wipe off the moisture with a dry cloth. •If the prism surface is smeared with oil or similar liquids it will repel the sample and obstruct the measurement. Wipe off the oil smear or contaminant with warm water.