DOT4 Brake Fluid Refractometer

The condition of brake fluid is important to automotive safety, reliability and brake system longevity. Brake fluid absorbs moisture over time. Increasing moisture levels in the brake fluid lower the boiling point, increase viscosity and cause corrosion of system components. Brake fluid with high moisture content can boil when extreme braking is required or a pad sticks. The effect of boiling is the same as when there is air in the system. The pedal sinks to the floor and stopping power is greatly reduced. The increased viscosity of brake fluid with high water content can affect both standard and ABS systems. In cold climates viscous fluid is no longer able to flow freely through the brake lines and fittings. There is increasing awareness among service technicians that water in brake fluid causes corrosion to system components including expensive ABS controllers.

The model DOT4 is used for measuring standard DOT4 brake fluid(DOT3 standard fluids scale), boiling point and water content of brake fluid at high temperature or in running(high temp scale).

Measurement Ragne Minimum Scale
DOT 4（standard fluids）
Boiling point 125-275℃/1-6 H2O
PLUS(SUPER) (Fords and Racing)
Boiling point 150-275℃/1-6 H2O 1% H2O