There are two main reasons for the leakage of the RY vertical heat transfer oil pump: First, there is a gap on the sealing surface. Second, there is a pressure difference on both sides of the sealing part. Eliminating or reducing any one factor can prevent or reduce the leakage and achieve the purpose of sealing. Seal classification of RY vertical heat transfer oil pump and analysis of causes of seal failure RY vertical heat transfer oil pump causes leakage mainly in two aspects: First, there is a gap on the sealing surface. Second, there is a pressure difference on both sides of the sealing part. Eliminating or reducing any one factor can prevent or reduce the leakage and achieve the purpose of sealing. The design pressure and the use pressure of the pump are objectively and cannot be reduced, so the sealing of the pump solves the problem of eliminating or reducing the gap between the sealing faces. Such gaps include gaps between the sealing faces and gaps within the body of the seal.
There are two main types of sealing devices for RY vertical heat transfer oil pumps: one is static seal and the other is dynamic seal. Static seals are usually typed with gasket seals, O-ring seals, etc. Dynamic seals mainly include soft packing seals, oil seal seals and mechanical seals.
Gasket Seals Gaskets are the basic components of static seals and are used in a wide range of applications. The selection of gaskets is mainly determined by factors such as pump delivery medium, temperature, pressure and corrosivity. When the temperature and pressure are not high, non-metallic sealing gaskets are generally used; when medium-pressure high temperature is used, Botaibang uses non-metal and metal combination gaskets. Non-metallic gaskets are most commonly used on pumps, and are typically made of paper, rubber and Teflon. When the medium is conveyed at -50 to 200 ° C, it is more suitable to use fluororubber. Because it is resistant to oil and heat, its mechanical strength is also its main feature. In the chemical pump, because the medium to be transported is corrosive, PTFE is generally used as the gasket material. As the field of pump use is more and more extensive, and the types of media to be transported are more and more, when selecting the gasket material, you should consult the relevant materials or make the correct choice after experimenting.
There are several reasons for the failure of the gasket:
1. The pressure acting on the gasket is insufficient. Due to the microscopic irregularities on the sealing surface, a number of annular grooves are sometimes machined on the sealing surface. If sealing is ensured, the RY vertical heat transfer oil pump must apply sufficient pressure to the sealing gasket to cause it to occur. Elastic or plastic deformation to fill these gaps. The pressing force of various gasket materials is usually given in the gasket manufacturer's sample or product manual, and can also be determined experimentally. Since the pressing force required for the gasket is not achieved during assembly or the compression bolt is loosened due to the vibration during the normal operation, the pressing force is lowered and the original elasticity is lost due to the aging deformation of the gasket material. The film fails and a leak occurs.
2, the internal material or thickness of the gasket material is uneven, RY vertical heat transfer oil pump and the use of cardboard with cracks or wrinkles, so that the gasket itself forms a gap, when the force acting on the gasket makes the gasket When the elastic deformation is insufficient to completely fill the gaps, the leakage is inevitable.
3. The material of the gasket is not compatible with the medium to be transported. Due to the versatility of the chemical properties of the chemical products transported by the pump, and the addition of some small amounts of additives to the fuel to increase the combustion value of the fuel or to change its combustion products, certain properties of the fuel change. It is not easy to select a gasket material suitable for the medium to be transported. Therefore, it is often the case that the gasket is corroded and leaks due to incompatibility.
O-ring seals Rubber O-rings are commonly used in pumps. Because of its simple shape, it is easy to manufacture and low in cost. No matter the overall size of the O-ring, its cross-sectional size is very small (only a few millimeters), so it is light in weight, consumes less material, is easy to use, and is easy to install and disassemble. The more prominent advantage is that the O-ring has a good sealing ability and a wide range of use. The static sealing working pressure can reach more than 100MPa, and the dynamic sealing can reach 30Mpa. RY vertical heat transfer oil pump is suitable for temperatures from -60 to 200 °C, which can meet the requirements of various media. Therefore, it is more and more widely used in the design of pumps.
The O-ring is mounted between the groove and the surface to be sealed with a certain amount of compression, and the resulting repulsive force imparts initial compressive stress to the smooth surface of the seal and the bottom surface of the groove. Thereby functioning as a seal. As the pressure of the sealed liquid increases, the deformation of the O-ring also increases, so that the pressure transmitted to the sealing surface also increases, and the effect of the seal also increases. This is why the O-ring seal has a good sealing ability.
O-ring seals are reliable, but leaks can occur if you do not pay attention to the conditions of use. There are usually the following situations:
1. The groove size of the O-ring is out of tolerance, especially when the depth dimension is too large, so that the amount of compression deformation after the O-ring is installed is insufficient to affect the sealing ability. Generally, the compression deformation amount of the O-ring after installation should be between 18% and 22%. When the cross-sectional size is large, the compression relative deformation is small, and when the cross-sectional size is small, the compression relative deformation is large.
2. The nominal size of the O-ring seal is too different from the actual installation size, and the O-ring is formed to work under the condition that the cross-sectional size is reduced after stretching, resulting in insufficient compression deformation and leakage.
3. When the O-ring is installed, the O-ring is scratched due to the smooth chamfering or rounding of the inlet of the sealing surface.
4. The material of the O-ring is not suitable for the sealing medium and is eroded and then fails. 5. O-ring seals will deteriorate after aging for a long time, and the elasticity will decrease and then fail. Therefore, the O-rings are generally replaced when the equipment is overhauled.
In addition, the hardness of the O-ring, the roughness of the groove and the sealing surface also affect the sealing effect of the O-ring. Phenomena also occur in pumps used in the chemical industry, so the choice of filler is also one of the factors considered for sealing.
Packing seal Put the compressive and resilient packing into the stuffing box and convert it into a radial sealing force by means of the axial pressing force of the gland to seal. This method of sealing is called a packing seal and this packing is called a packing. Because the packing sealing structure is simple in form, convenient to replace, low in price, suitable for rotation speed, pressure, and wide medium, it is widely used in pump design. When conveying medium temperature medium, the packing seal is generally provided with a packing ring, which is connected with the high pressure chamber of the pump or externally connected with a liquid medium with a certain pressure. The RY vertical heat transfer oil pump can cool, lubricate, seal or rinse. Since the packing seal is a contact seal, there is bound to be friction and wear problems. The size of friction and wear is mainly determined by the pressing force of the packing gland. The high pressure can improve the sealing effect, but it will increase the power consumption and wear of the bushing, and vice versa. Therefore, the pressing force of the gland should be adjusted according to the amount of leakage and the temperature of the leaking medium, and the packing should be replaced or replenished if necessary. A reasonable leak of the packing seal is typically 10-20 ml/min. When introducing liquid from the outside, it should be ensured that the liquid has good chemical stability, neither contaminating the medium transported by the pump, nor reacting with the medium to produce precipitates and solid particles, and also having good impregnation with the filler. And long-lasting retention, which provides a good and long-lasting seal.
Oil seal seal oil seal is a self-tightening lip seal. It has simple structure, small size, low cost, convenient maintenance, low resistance torque, and can prevent medium leakage. RY vertical heat transfer oil pump can also prevent external dust and other. Harmful substances invade, and have a certain ability to compensate for wear, but not high pressure, so generally used in low pressure applications. The oil seal should be mounted on a shaft with a manufacturing accuracy of h8 to h9 and a surface roughness of 1.6 to 0.8 μm and surface hardened. The sealing medium should not contain solid particles and impurities, which would cause rapid wear of the oil seal and shaft and void the seal. Botou Taibang Pump & Valve Manufacturing Co., Ltd. Mechanical seal mechanical seal is the main method of modern pump shaft seal. Although it is not easy to use it to achieve complete leakage, it is possible to achieve a small, fully acceptable leakage. of. However, there are often embarrassing situations in the operation of the pump. What is the cause of the mechanical seal failure?
1. The material selection of the mechanical seal is not suitable. The material of the mechanical seal does not match the medium being conveyed. At work, the sealing element is quickly corroded, dissolved or worn, thus losing the ability to seal. Therefore, the choice of the material of the mechanical seal according to the nature of the transport medium is a prerequisite for ensuring its sealing function and normal life.
2. The flushing condition of the mechanical seal does not meet the design requirements. RY vertical heat transfer oil pump must be flushed with a certain pressure and a certain flow of flushing liquid when transporting media that is easy to crystallize or have fine particles. Otherwise, the crystal or particles will accelerate the wear of the seal pair and affect the automatic wear of the seal pair. A leak occurs due to compensation. Therefore, according to the nature of the transport medium, it is necessary to configure not only the corresponding flushing pipeline, but also the instrument and device with monitoring and regulating functions to ensure that the pressure and flow of the flushing fluid meet the design requirements, in order to maintain the normal operation of the machine seal, which is often Neglected by the user.
3. The pressure that each mechanical seal can withstand is limited. Because the pressure in the sealed chamber is not accurate, the pressure in the sealed chamber exceeds the pressure that the mechanical seal can withstand, resulting in leakage. It is also a common seal. One of the reasons for failure.
4. The working temperature of the mechanical seal cannot exceed its specified value. In the design of the cooling pipeline, the cooling effect is often reduced due to insufficient flow of the cooling medium; in the design of the RY vertical heat transfer oil pump without the cooling pipeline, the mechanical seal is often dry due to the air in the sealed chamber. Friction state. In both cases, the mechanical seal's motion seal pair operates too hot and accelerates wear, resulting in seal failure.
5. When using a single spring mechanical seal, the correct combination of the direction of rotation of the spring and the direction of rotation of the pump rotor also occurs. RY vertical heat transfer oil pump is not specified in the design, or negligence in assembly, the spring force of the mechanical seal is increased due to the rotation of the rotor, but the result is insufficient pressure of the moving ring and the static ring friction pair. Form a leak.
6, the bearing's severe wear or damage, the pump shaft produces serious axial turbulence, RY vertical heat transfer oil pump is also one of the reasons for mechanical seal leakage. With the development of scientific technology, new sealing forms and sealing materials have emerged, which will inevitably have a direct impact on the pump sealing technology. Long-life, zero-leakage pump products will be promoted and applied in more and more places.
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