Did the "sizzling" sound of gas leakage when plugging the nozzle at the gas station make you feel uneasy? For most people, the first reaction when encountering this situation is to contact maintenance. However, they often don't realize that the problem usually lies in the unnoticeable sealing ring. This small component, with a diameter of only 3-4 centimeters, is the "first line of defense" against gas leakage. Understanding its workings can save a lot of trouble.
The seemingly insignificant sealing ring actually undergoes "high pressure, temperature difference, and friction" for a long time. Frequent failures are usually caused by the combination of multiple factors. The specific reasons can be classified into 4 core categories:
1. Extreme conditions "accelerate aging": freezing at low temperatures, softening at high temperatures
This is the most common failure reason for the sealing ring of the lpg nozzle. When refueling with LNG, the medium temperature drops as low as -162℃. If an ordinary rubber sealing ring (with a low-temperature resistance limit of mostly -40℃) is used, the low temperature will cause the material to harden, contract, and even develop tiny cracks - when the sealing ring cannot tightly fit the gap between the gun head and the interface, gas leakage will occur.
2. High-frequency friction "wear and tear": Frequent insertion and removal lead to rapid wear
The gas filling gun needs to be repeatedly inserted and unplugged every day, causing continuous friction between the sealing ring and the inner wall of the interface. Taking a gas filling station that inserts the gun 50 times per day as an example, the sealing ring will undergo more than 1,500 cycles of friction per month. Over time, the surface will gradually develop "sharp edges" and "indentations", and even be scratched by tiny impurities at the interface (such as metal debris, dust) - these damages will damage the integrity of the sealing surface, causing high-pressure gas to leak through the gaps.
3. Material selection "mis-matched scenarios": Using common parts to deal with special media
Some gas filling stations, in an attempt to save costs, use general rubber sealing rings instead of specialized ones, which accelerates the occurrence of faults. For example:
If a CNG gas filling gun is wrongly used with an oil-resistant sealing ring, it will be corroded by the trace oil in the gas, resulting in "swelling and stickiness";
If an LNG gas filling gun uses a common nitrile rubber ring instead of a low-temperature-resistant perfluorinated ether rubber ring or UPE material ring, it will definitely crack at low temperatures;
The mismatch between the material and the medium, as well as the working conditions, is equivalent to making the sealing ring "work in an unsuitable environment", which naturally leads to problems.
4. Maintenance errors "human damage": Installation with violence, lack of inspection
Neglects in daily operation and maintenance can also cause the sealing ring to fail prematurely:
If the installation is too forceful or the interface slot is not aligned and the sealing ring is forcibly pressed, it will cause the sealing ring to "twist and deform", appearing to be installed properly but the sealing surface has already become uneven;
If the gun head interface is not cleaned regularly, impurities adhere to the surface of the sealing ring, not only intensifying the friction but also forming "gaps" on the sealing surface;
If inspections are not conducted at regular intervals (suggested once a month), when leakage is detected, the sealing ring often already has severe wear or even fracture.
If there is a leak, don't rush to replace the part immediately. Three steps can help you determine it:
Check the appearance: After removing the nozzle, if the sealing ring has cracks, missing corners, or a sticky surface, replace it with a new part of the same model (commonly in the specifications of inner diameter 32mm and outer diameter 40mm);
Test the elasticity: Press the sealing ring with your finger. If it cannot rebound or the pressed area collapses, it indicates aging and failure;
Look at the slot: If the sealing ring is intact but still leaks, check if there are scratches or deformations on the installation slot - slot wear will cause the sealing ring to not be fixed properly. In this case, the nozzle must be replaced.
There are also specific instructions for replacement: First, use a clamp to remove the elastic retaining ring, then remove the old sealing ring, install the new part, make sure the opening faces outward, and finally reset the retaining ring in sequence. It is recommended to use the yellow low-temperature resistant model for lpg nozzles, as its UPE material can withstand extreme temperature differences, while the ordinary CNG guns can use black rubber material.
Although the sealing ring is small, it directly affects safety. Two points to note: First, it should be replaced regularly. Gas stations should conduct an inspection every 3 months, while gas filling points in taxis and other frequently used scenarios need to be replaced monthly. Second, make sure to choose qualified products. Poor-quality sealing rings may contaminate the gas and may also shatter under high pressure, causing danger.
The next time you encounter gas leakage from the gas filling gun, you might as well take a look at this small component - perhaps you can solve the problem without waiting for maintenance. After all, in gas safety, the insignificant sealing ring is actually the most crucial "safety guardian".
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