The hand-held refractometer is commonly used to check coolant concentration, based upon the refractive index of the coolant solution. There are many people out there that do not fully understand how to use a refractometer and why it is important in relation to the care and maintenance of water based metal working fluids. What seems to be the most difficult thing for most people to grasp, including machine shop owners and operators is the “Refractive Index Multiplier”
The most important thing to remember when using a refractometer is that they read on a Brix scale not actual percentages. To get actual percent of the coolant concentration you must multiply the refractometer reading by the coolants refractive index multiplier which can typically be found on the tech data sheets. Every coolant, no matter who manufacturers it has a guideline for refractive index multipliers.
For example, TRIM Microsol 585XT has a refractive index of 1.22, and if you want to run this at a 7% solution mix, you should be looking for 5.7 on your refractometer.
Operation:
• Calibrate your refractometer each time you use it by placing a drop of shop water onto the prism and lower the cover plate. It should read zero. If not, adjust the set screw.
• After wiping the prism clean, place a few drops of coolant onto the prism. Try to take the coolant from the coolant nozzle and not from the coolant sump. Close the cover and read.
• Refer to coolant specifications for correct reading.
• Keep in mind that tramp oil will blur the line on the refractometer.
• Remember that this is an optical instrument and should not be dropped or handled roughly
For additional info on Refarctometer sales contact me at d.foster@bellnet.ca
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