- Measure the specific gravity of the coolant with a hydrometer (pic. 5.6).
Pic. 5.6 Using a hydrometer to measure coolant density
- Measure the temperature of the coolant and, depending on the temperature, calculate the concentration of antifreeze in the coolant.
The relationship between the concentration of antifreeze in the coolant and the specific gravity
Specific gravity at a coolant temperature of 20°C, g/cm3 | Freezing point°C | Coolant concentration, % |
1,050 | -16 | 30 |
1,058 | -20 | 35 |
1,067 | -25 | 40 |
1,074 | -30 | 45 |
1,082 | -36 | 50 |
1,090 | -42 | 55 |
1,098 | -50 | 60 |
Example
The freezing point of the coolant is -20°C at a weighted specific gravity of 1.058.
Warning. If the coolant concentration is lower than 30%, the anti-corrosion properties of the coolant are reduced. At a concentration of more than 60%, the frost resistance of the coolant deteriorates.