With reference to relevant documents of the Ministry of Railways, if there is slight air leakage in the electric butterfly valve system during vehicle operation, it can be operated to the end point at one time without affecting braking (pressure in the main air pipe ≥ 550 kPa); In case of accidental rupture, perforation or serious air leakage of the electric butterfly valve, the vehicle must be thrown off at the departure station, and the air source of the two electric butterfly valves on the bogie where the faulty electric butterfly valve is located must be cut off at the passing station, and the vehicle will run to the destination at a speed of less than 120km/h. When cutting off the air source, it is not necessary to cut off the air source of the electric butterfly valve of the whole vehicle, let alone treat the vehicle as a closed door vehicle.
During maintenance, if slight air leakage is found in the upper cover and capsule of the self sealing electric butterfly valve, it can generally not be treated, or the air in the electric butterfly valve can be discharged and then refilled. The air leakage can generally be eliminated.
The electric butterfly valve with repeated slight air leakage and serious air leakage shall be disassembled for inspection, and the faulty parts or the whole valve shall be replaced when necessary.
After the capsule fault electric butterfly valve has been used for a period of time, due to the long-term exposure of the capsule to the air and the effects of ozone, sunshine, rain, as well as the corrosion of organic solvents such as acid, alkali, paint, etc. on the capsule during the maintenance process, the outer surface of the capsule will appear uniform and fine cracks, that is, cracks. The surface cracks are generally confined to the outer layer, and the inner sealing layer will not be damaged. However, there are also a few capsules with uneven cord density in local areas during the manufacturing process. After a certain amount of fatigue, the capsules with small cord density will produce large radial cracks, which will expand to the middle cord layer. Field statistical data show that generally, when the length of the crack on the surface of the capsule is more than 30 mm and the width is more than 1 mm, or when there is a dense pinhole shedding at the crack, the crack has expanded to the outer cord of the cord layer.
The test results show that the electric butterfly valve still maintains air tightness and elasticity when there is serious cracking on the surface of the capsule.
The electric butterfly valve with relatively serious surface cracks was filled with high-pressure water, so that its internal pressure slowly rose to 2.0 MPa, and the electric butterfly valve capsule was not damaged. This shows that the electric butterfly valve still has sufficient pressure strength.
During operation, the contact part between the capsule and the upper cover and the lower seat will produce relative sliding friction, which will wear the surface of the capsule, even to the capsule cord layer in serious cases. Especially for the bogie with large lateral swing, the contact part between the electric butterfly valve capsule and the upper cover or lower seat edge will be worn, so attention should be paid to inspection during maintenance.
The capsule surface is allowed to have local slight scratch and wear, but if it is worn to the cord layer, it should be replaced with a new one.
During the manufacturing process of the electric butterfly valve capsule, the inner and outer layers of the capsule and the cord layer are poorly bonded. During the use, air will enter and stagnate between the inner and outer layers and the cord layer, causing local blistering. Because of the accumulated air, it should feel soft when pressed by hand.
It should be noted that at present, there are local unevenness on the surface of the capsule of the SYS series electric butterfly valve for 25T vehicles, which is a bulge formed by the normal lapping of the capsule cord valve on the outer side of the capsule during the production process. When you press it with your hand, it feels dense. This phenomenon is easily mixed with the blister on the outer layer of the rubber capsule.
During vehicle operation, if the continuous length of the cracks on the surface of the capsule does not exceed 30 mm and the width does not exceed 1 mm, the electric butterfly valve can continue to be used normally under the normal inflation state; Capsules with blisters on the surface, cracks exceeding the limit and dense pinhole shedding can be replaced in combination with the next A2 or A3 repair procedure; For the damaged cord or exposed capsules, the shunting shall be arranged immediately to replace them.