2016年12月28日星期三
Install the mechanical seal of the pipeline sewage pump
First, GW pipe sewage pump to ensure quality parts of the sewage pump mechanical seal in the factory to be done sealing performance test, and a certificate. Mechanical seal after a long run, so that the ring and the static ring wear, spring and shaft corrosion wear, seal apron wear, aging, deformation, etc., can cause leakage of the seal must be repaired or replaced. The sealing surfaces of the moving ring and the stationary ring shall not have any cracks, angles, scratches, pittings, flashes and eccentric wear, scratches, and pits that can not penetrate the entire sealing face. If the use of repair movement ring, the static and dynamic ring of the convex height of not less than 3mm, and a single boss height of not less than lmm, so as not to affect the heat. After moving the ring should be installed to ensure flexibility in the axis of movement, the dynamic ring pressure spring should be able to spring back to keep the static and dynamic ring vertical and parallel. Static and dynamic ring seal apron specifications in line with the drawings, the surface shall not be damaged, uneven thickness and uneven hardness, in the overhaul to replace the sealing apron. The outer surface of the spring should be clean and free from corrosion. The length profile and pressure test shall be carried out before use. The pressure difference between each set of springs in the specified compression length shall meet the requirements. The pressure error of each set of springs shall meet the requirements. Free length tolerance does not exceed 0.5mm, the compression can not be too large too small, the required error of ± 2mm. Gland and pump shaft can not use the same material, both sides of the parallel end of the tolerance and the axis of the non-vertical tolerance does not exceed ± 0.20mm.
Second, the pipeline sewage pump to ensure adequate cooling Lubrication adjustment cooling pipe valve opening, to ensure that the mechanical seal cooling pipe patency, open the tank when the drain valve to drain the net sealed cavity gas.
Third, the installation of pipeline sewage pump to ensure the accuracy of dismantling pump mechanical seal, the static ring to clean, and friction in the Vice-surface coated with a small amount of clean oil, to take into account the high-pressure side and low pressure side, is prohibited bump. Static ring gland installation force to be uniform, to prevent bias, with a feeler check, the upper and lower left and right position of the deviation is not greater than 0.05mm; check the gland and shaft diameter with the gap around to be uniform, the points allow deviation is not Greater than 0.1ram. Install the pump mechanical seal parts of the pump shaft radial runout of not more than 0.05mm. And the pump cover and sealed end cover, to carefully review the mechanical seal installation location size, if the positioning size does not meet the requirements, can be used in the steel sleeve between the sleeve adjustment, but the steel pad to high precision, the thickness difference of not more than 0.01mm . Measure the radial runout of the mechanical seal and the face runout of the sealing surface to meet the requirements. On the operation of the mechanical seal, where there is loose gland to move the sealing surface of the case, the ring parts must be replaced, should not be re-tightened to continue to use
. Because in this loosening, the friction of the original trajectory will change, the contact surface of the sealing performance can easily be destroyed.
Fourth, the end of the sewage pipe to adjust the pressure side of the sewage pressure ratio is related to sealing performance and service life of the important parameters, it is sealed with the structure type, spring size and medium pressure. Than the pressure is too small is easy to leak, often given by the manufacturers to a suitable range, the end face than the pressure generally take 3 ~ 6kg / cm2. Adjust the specific pressure is to adjust the compression size of the spring. The free length of the spring is denoted by A, the spring load produces a unit of compression, and the required specific pressure is denoted by P, which are the parameters given by the manufacturer. The compressed size is denoted by B, then P / A-13 = k, resulting in 13 = A-e / k, which is the size of the spring after installation compression. If the spring after the installation of the size is too large, in the spring seat and spring to increase the adjustment between the pad thickness, size is too small to reduce the adjustment of the thickness, adjust the thickness of the mat with a micrometer measurement.
2016年12月27日星期二
Schematic diagram of centrifugal pump
First, an overview of centrifugal pumps
1, the pump is to transport liquid and increase the pressure of the machine.
2, the pump is divided into chemical pumps, water pumps.
3, the main differences: special materials and design, to prevent corrosion and adapt to chemical processes, including the structure, shaft seals, materials and maintenance difficult.
4, chemical pump requirements
(1) to adapt to the chemical process requirements and reliable operation.
(2) corrosion resistance, wear resistance.
(3) to meet the no leakage requirements.
(4) high temperature or low temperature and can work continuously.
The structure of centrifugal pump
Mainly include the volute-shaped pump body, pump shaft, impeller, mechanical seals, bearings and gland and other major accessories, in addition to some other accessories did not figure out the figure, such as suction pipe, water pipe, valve, control valves, irrigation Funnel and pump seat and so on.
In order to make the centrifugal pump to work properly, the centrifugal pump must be equipped with a certain pipeline and pipe fittings, which is equipped with a certain pipeline system, known as centrifugal pump centrifugal pump. The figure shows the general schematic diagram of the centrifugal pump, there are bottom valve, suction pipe, outlet valve, outlet pipelines and so on.
Performance characteristics of centrifugal pumps
In explaining the performance characteristics of centrifugal pump before the industry to see what is centrifugal pump, centrifugal pump is the use of impeller rotation leaving the water centrifugal movement to work. Pump before starting, must pump shell and suction tube filled with water, and then start the motor, so that the impeller and water pump shaft to do high-speed rotary motion, the water centrifugal movement, was thrown to the outer edge of the impeller, Road into the pump pressure water pipes. Centrifugal pump performance characteristics are the following six major features.
1, energy efficient: CFD computational fluid dynamics, analysis and calculation of the pump pressure distribution and velocity distribution, and optimize the pump flow channel design to ensure that the pump has an efficient hydraulic lines, improve the efficiency of the pump.
2, easy installation and maintenance: vertical pipeline structure, the pump can be the same as the import and export of valves installed in any position in the pipeline and in any direction, installation and maintenance is very convenient.
3, smooth, safe and reliable: the motor shaft and water pump shaft for the coaxial straight, concentric high, smooth operation, safe and reliable.
4, stainless steel sleeve: shaft seal position is relatively easy to be corrosion of the Department, once the direct-type pump shaft is rusted, easily lead to mechanical seal failure. STG pump here with mosaic stainless steel sleeve, to avoid corrosion, improve shaft life, reduce operation and maintenance costs.
5, bearings: pump with the motor, Y [Y2] 280 the following shaft end bearings [including Y180 following fan end bearing] closed bearings, normal use, maintenance-free motor bearings.
6, mechanical seal: mechanical seal base pieces of rubber bellows general use of the structure, the traditional mechanical seal on the shaft seal from the O-ring line seal to rubber pieces of the two-way seal in the water when the media to improve the sealing effect.
What is the cavitation of a centrifugal pump?
What is the cavitation of the centrifugal pump? Liquid at the impeller inlet flow rate increases, the pressure is lower than the working temperature of the corresponding saturation pressure, will cause a part of the liquid evaporation (ie vaporization). Evaporation of the bubble into the higher pressure areas, the pressure suddenly condensed, so the liquid around to add here, resulting in hydraulic shock. This phenomenon is called cavitation.
The so-called cavitation refers to: centrifugal pump starts, if the pump in the presence of air, because the density of air is very low, the centrifugal force generated after rotation is very small, so the impeller center area formed by low pressure is not enough to level below the pump inlet Of the liquid suction pump, can not transport the phenomenon of fluid.
Due to continuous local impact, the surface of the material will gradually fatigue damage, causing the metal surface erosion, and then the size of the cellular cavities, in addition to damage caused by metal parts, but also produce chemical corrosion phenomena, oxidation equipment. Cavitation process is unstable, the pump will produce vibration and noise, while the bubble will block the impeller channel, resulting in head, flow rate decreased efficiency. Before the start of the centrifugal pump must be filled with liquid after the pump shell, before starting, otherwise it will cause the pump heat, vibration, a liquid reduction, damage to the pump (referred to as "cavitation") caused by equipment accidents!
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