Changing of Brake Fluid
To drive a car without brake has no meaning, therefore brake has very important role in driving a car. Brake is a safety device and used occasionally and on emergency basis. A special attention is required to keep this in proper order, therefore so many changes has made in brake parts from starting to update in automobile. In some countries, it is compulsory to get a certificated about the brake assembly every two years. Brake fluid is one of the important ingredients in brakes. There are six liquid products, which are to be change during the maintenance. The brake fluid is on of them.
Within the braking system of most of automobiles exists brake fluid expect air brakes, a highly critical component essential to brake operation. Brake fluid serves to produce the braking action as well as to protect and to lubricate brake system components. Every driver depends on brake fluid for stopping capability. The use of a high quality brake fluid is essential to assure the safety of the driver and passengers traveling in the automobiles.
Brake fluid has contaminated in two years or less in the vehicles. This is because the fluid absorbs moisture, which works its way through the hydraulic system. Under heavy braking conditions, such as those encountered in mountainous or hilly driving or when towing a trailer, moisture in the overheated fluid vaporizes (boiling point of water is lower than that of brake fluid) and braking efficiency is reduced. The fluid attracts moisture through microscopic pores in rubber hoses, past seals and exposure to the air. The problem becames worse in wet climates where humidity is high. Even under normal driving conditions this condition can develop if the brake fluid is seriously contaminated.
As the concentration of moisture increases, it causes a sharp drop in the fluid's boiling temperature. A brand new DOT 3 brake fluid must have a dry (no moisture) boiling point - ERBP of at least 205 degrees C, and a wet (moisture-saturated) boiling point -Wet ERBP of no less than 140 degrees C. Most of the new DOT 3 fluids exceed these requirements and has a dry boiling point in the range from 220 degrees C to 250 degrees C.
Only one percent water in the fluid can lower the boiling point of a DOT 3 to 187 degrees C. Two percent water reduces the boiling point down to around 160 degrees C, and three percent will take down to 145 degrees C-which is getting dangerously close to the minimum DOT and OEM requirements.
DOT 4 fluid, which has a higher minimum boiling temperature requirement (230 degrees C dry and 155 degrees C wet) soaks up moisture at a slower rate but suffers an even sharper drop in boiling temperature as moisture accumulates. Three percent water will lower it's boiling point as much as 33%. There is a silicone type brake fluid which is not absorbed the moisture but it has so many of other type of problems therefore it is not used in regular basis.
Moisture also causes a number of problems like :
1. Viscosity rises in lower temperature, so more force to be applied for brake every time.
2. Spongy brake paddle due to presence of water vapour.
3. Brake failure chances increase in low temperature due to formation of ice crystal in line.
4. Moisture wears the component failure due to internal rust and deterioration.
5. Moisture initiates the oxidation of brake fluid components to reduce its life.
Therefore it is recommended that brake fluid should change every two years.
The average driver uses his or her brakes approximately 75,000 times a year and expects them to function properly each and every time. Due to so much times operation, fine particle sludge has formed, which may causes following problems.
1. May chock the brake line.
2. Increase the viscosity of brake fluid so extra force is required every time, indirectly it takes more time to apply the brake in full strength thus accident chance has increased.
Therefore it is recommended that brake fluid should change every 40000 kilometers.
It is observed that vehicle owners are not giving so much attention in changing the brake fluid and during the checking it found that the 80% cars are not met the specification. The owners are also not so much worried the changes because they not facing any trouble during the drive.
Vehicle manufacturers are also evenly divided, on whether or not brake system should be change periodically or refilled with fresh fluid . All important manufacturers are recommending to change the fluid on specific intervals varies from 25000 kms. to 60000 kms. and 12 months to 30 months. The manufacturer Maintenance schedule is the best guide for a vehicle owner. At last changing of the fluid in a vehicle is always a change for the better.