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2025
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Is the air passage antifreeze liquid promoted by merchants really reliable?
As the weather gets colder, the northern regions are gradually experiencing their first snowfall. Recently, many drivers have reported on forums that trailer brake valves often freeze, and some merchants are aggressively promoting air line antifreeze. Today, let's talk about whether air line antifreeze is reliable.
▎Tracing the Root Cause: Why Does the Relay Valve Freeze?
The relay valve is an important component of the heavy truck brake system. Its air inlet is connected to the air reservoir, and its air outlet is connected to the brake chamber. During braking, it can accelerate the charging process of the brake chamber, playing a crucial role in the brake system.
So why does it freeze? The main reason is that there is water vapor in the compressed gas. When the water vapor concentration reaches a certain level, it condenses into ice when cooled, and over time, it can block the control valve.
So why is there water vapor in the gas? The main reason is a problem with the air-drying section before the brake system, causing compressed air to enter the air tank without being thoroughly dried. According to our statistics, water vapor is usually generated due to the following reasons:
1. Spiral cooling tube is too short: The compressed air coming out of the air pump is very hot and needs to pass through the spiral cooling tube to cool down to below 65 degrees, and then go through the dryer to remove moisture.
If the spiral cooling tube is too short, the cooling effect is poor, and the moisture in the hot air may not be completely filtered when passing through the dryer. Once it enters the air circuit and tank, it easily condenses and freezes.
2. Dryer failure: After long-term use, the particles inside the dryer gradually become saturated with water. At this point, the dryer is no longer effective and cannot filter the moisture in the compressed air.
3. Air tank not drained regularly: After the moisture in the compressed air condenses, most of it is stored at the bottom of the air tank. If it is not regularly drained, it can be carried by the airflow into the valve body and freeze.
▎Getting to the Bottom of It: Is Air Circuit Antifreeze Reliable?From the three points above, it can be seen that the reason for the pilot valve freezing is that there is a problem with the air drying system, and the water vapor concentration in the compressed air is too high. According to normal reasoning, to prevent the brake valve from freezing, one should find ways to curb the generation of water vapor.
However, the brake master shops and auto parts dealers often recommend a different approach for air line antifreeze. Air line antifreeze is a low-freezing-point mixture that contains ingredients like alcohol, which have very low freezing points. When this antifreeze is added to the air lines, it mixes with water, lowers the freezing point, and prevents icing.
This method does work, and it takes effect immediately. However, it is a temporary solution rather than a fundamental one. Once the effective substances in the antifreeze evaporate, the actuator valve can still freeze in low temperatures. Moreover, the components in the antifreeze can corrode the pipes, rubber gaskets, and metal parts, posing a significant safety risk over time.
In addition, the brake antifreeze sold on the market is usually a volatile and flammable substance. As the brake system vents, it can be expelled outside the vehicle, posing a hidden fire hazard. This detail is especially important for vehicles transporting hazardous chemicals. ▎By analogy: Can pure alcohol be used?Regarding the problem of brake valves freezing, many experienced drivers on forums recommend using pure alcohol. Alcohol is volatile, and when it mixes with moisture, it can lower the freezing point, which does help to prevent the brake lines from icing.
It can be seen that the principle of action of alcohol and airway antifreeze is the same; they both address the symptoms rather than the root cause, and they also pose potential risks of corroding the airways and components.
So alcohol, like airway antifreeze, is only suitable for short-term emergency use. For long-term considerations, the most reliable approach is still to solve the problem of drying compressed gas.
▎A once-and-for-all solution: What are the reliable ways to solve this?
1. Before the onset of winter, maintenance of the valve body should be carried out, and a small amount of petroleum jelly should be applied inside the valve body to aid in the lubrication of the piston within the valve body.
2. Check whether the compressed air in the air storage tank can dissipate heat effectively. If the compressed air is too hot, the length of the coiled pipe should be increased.
3. Install an air condenser at the outlet of the air compressor to condense and separate impurities such as water and oil in the compressed air, ensuring that the air dryer can function more effectively.
4. Check whether there is water accumulation in the air storage cylinder and ensure regular drainage. If there is excessive water, consider replacing the dryer.
▎Editor’s NoteAs can be seen, the anti-freeze for air circuits that merchants aggressively promote is not necessarily the best choice. For the long-term health of your car, it is better to choose a suitable and reliable maintenance method. With winter approaching, all experienced drivers should take extra care of their cars. Finally, I wish everyone a happy drive and a safe return home!
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