Issues related to certification of fire pumps, what causes fire pumps to leak, and how to solve them
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3C certification for fire pumps is required to submit documents. Since September 1, 2015, all fire protection products included in the compulsory product certification catalog have no compulsory product certification certificate, and the label must not compulsorily authenticate the product identification, and must not be manufactured, sold, imported or used in other business activities. 1. Preliminary application documents for 3C certification of fire pumps For the mandatory 3C certification application of fire pumps; fire pump factory inspection questionnaire; a copy of the business license of the enterprise legal person applicant; a copy of the applicant's corporate organization code certificate; Assembly drawing, working principle of fire pump; list of key components or raw materials; application in the Chinese manual of certified fire pump; differences between different types of fire pump products in the same application; organization chart of fire pump production enterprise; 10.3C certification fire pump application program flow chart; 11. List of main production equipment of fire pumps; 12. Daily inspection of key equipment and equipment list of fire pumps; 13. Fire pumps of each model in the same application (two copies) 14 Other relevant information is needed when needed; II. When providing product inspection, the following information should be provided: Mandatory fire pump 3C certification application Fire pump general assembly drawing, fire pump working principle diagram, key parts or raw material list; different models of products have the same application in fire pumps; Leakage of centrifugal pump (1) The pressure wave due to pressure and mechanical seal leakage, the pressure is high. Due to the large spring specific pressure and total pressure design and the pressure in the seal cavity exceeds 3 MPa, the specific pressure on the seal end face will be too large and difficult The formation, liquid film sealing end face is severely worn, the heating value is increased, and the sealing surface is caused by thermal deformation. Solution: When the assembly machine is sealed, the spring compression must be performed in accordance with regulations, not too large or too small, and mechanical sealing measures should be taken under high pressure conditions. In order to make the lateral stress reasonable and minimize the deformation, you can use hard alloy, high compressive strength materials such as ceramics, and strengthen the lubrication and cooling measures to choose the best transmission method. (2) the starting point, process and pump machinery of vacuum operation The stop caused by the leakage of the seal, because the pump inlet is blocked, and the pumping medium contains gas, it is easy to cause a negative pressure seal cavity. If the seal cavity is under negative pressure and dry friction causes the seal, the built-in mechanical seal will cause a (water) leak phenomenon, and the vacuum seal Different objects from the seal directivity of the positive pressure seal, and the adaptability of the mechanical seal have a certain direction. Countermeasure: Adopt double-end mechanical seal to improve lubrication conditions and seal performance. 2. Pipeline centrifugal pump caused by medium leakage. (1) After the mechanical seals of most submersible sewage pumps are removed, the elasticity of the static ring and the auxiliary seal ring is not enough, and some of them have decayed, and the seal of the mill even leaks the shaft. Due to the high temperature, the weak acid and alkali of the sewage, and the corrosion of the auxiliary rubber sealing ring, the mechanical leakage is too large. The dynamic and static ring is a nitrile rubber sealing material-40, not resistant to high temperature, acid and alkali, and water. Acidic and alkaline corrosion. Countermeasures: For corrosive media, rubber is used for high temperature, weak acid and weak alkaline fluorine rubber. (2) Mechanical seal leakage caused by solid particles. If solid particles enter the sealing surface, they can scratch or accelerate the wear of the sealing end face, while the scale and oil contamination are on the shaft. Because the friction pair wears faster than the surface accumulates, the wear of the ring is difficult to compensate, and the hard friction pair operates longer than the hard life of the graphite friction pair because the solid particles are inlaid with graphite seal rings. Countermeasure: In the place where solid particles are easy to enter, the mechanical seal of the tungsten carbide and cemented carbide friction pair should be selected. 3. Other problems caused by mechanical seal leakage. Mechanical seals have unreasonable places such as design, selection, and installation. (1) The compression amount of the spring must be carried out in accordance with regulations, not too large or too small, with an error of plus or minus 2 mm, increasing the compression amount with a large end pressure ratio, excessive frictional heat, resulting in accelerated thermal deformation and wear of the end sealing surface, and the pressure is The ring end is under pressure and cannot be sealed. (2) Install the shaft end or sleeve end face of the movable ring seal ring, the seal gland or the end face of the housing of the static ring seal ring, and trim it to avoid touching the ring seal ring during the assembly process. 4. Pipeline centrifugal pumps often leak. Mechanical seal leakage accounts for more than 50% of the entire maintenance pump, and the operation of the mechanical seal directly affects the normal operation of the pump. The summary analysis is as follows. 1. Periodic water leakage (1) Pump rotor shaft has large momentum, and the secondary seal and shaft are too large. The moving ring cannot move flexibly on the shaft. After the pump rotates, the motion and static ring wear out, compensation is not compensated. Countermeasure: When the mechanical seal is assembled, the axial momentum of the shaft should be less than 0.1 mm, and the interference between the auxiliary seal and the shaft should be moderate. While ensuring the radial seal, the shaft on the ring must be flexibly moved. Free bounce. (2) Insufficient lubricating oil on the sealing surface, resulting in dry friction or brushing the sealing end surface. Countermeasure: The oil level of the oil tank should be higher than the dynamic and static ring sealing surfaces. (3) Periodic vibration of the rotor. The reason is the imbalance between the stator and the upper and lower covers and the middle or the impeller and the main shaft, cavitation or bearing damage, which shortens the seal life and causes leakage. Countermeasure: The above problems can be corrected according to the maintenance standards.