Cutting fluid mix ratio calculator
Cutting fluid is mixed by volume percentage. Getting it wrong causes rust at one end and dermatitis at the other.
L
%
Concentration equals Brix reading times this factor. Check the product data sheet.
%
Concentrate needed
5.600L
- Water needed
- 74.40 L
- Mix ratio, water to concentrate
- 13.29
- Expected refractometer reading
- 4.67 Brix
- Concentrate to add to correct the tank
- 2.400 L
- Reading at the current concentration
- 2.67 Brix
Show the working
- Tank volume = 80
- Target concentration = 7
- Refractometer factor = 1.5
- Current concentration = 4
- Concentrate needed = 80 * 7 / 100 = 5.6
- Water needed = 80 - 5.6 = 74.4
- Mix ratio, water to concentrate = 5.6 > 0 ? 74.4 / 5.6 : 0 = 13.2857
- Expected refractometer reading = 1.5 > 0 ? 7 / 1.5 : 0 = 4.666 67
- Concentrate to add to correct the tank = 80 * (7 - 4) / 100 = 2.4
- Reading at the current concentration = 1.5 > 0 ? 4 / 1.5 : 0 = 2.666 67
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- concentrate volume = tank x concentration
- concentration = Brix reading x refractometer factor
Add concentrate to water, never water to concentrate, or the emulsion inverts and separates.
Coolant evaporates as water, so a tank drifts richer over time. Top up with water and check with a refractometer.