Thread Content
Centrifugal pumps are divided into single-stage centrifugal pumps and multi-stage centrifugal pumps. The most obvious difference between single-stage and multi-stage centrifugal pumps lies in their impellers. Single-stage centrifugal pumps are divided into self-priming centrifugal pumps and non-self-priming centrifugal pumps. It is applied in fields such as mining, power, steel, metallurgy, municipal services, chemicals, textiles, papermaking, oil, petrochemicals, and food and pharmaceuticals. Working principle of single-stage centrifugal pump: The key component in a centrifugal pump is the impeller; the blades in this impeller force the liquid inside the pump to rotate. Under the effect of centrifugal force, the liquid is thrown outward, and the pump casing collects this liquid before discharging it at the outlet ； After the liquid inside the pump is thrown out, new liquid enters the pump under atmospheric pressure, thus continuously transporting the liquid. Product performance of single-stage single-suction centrifugal pumps: 1. The pump features a structure in which the inlet and outlet diameters are identical and lie on the same center line; it can be installed in pipelines just like a valve. It has a compact and attractive design, occupies little space, and requires low construction costs. If equipped with a protective cover, it can be used outdoors. 2. The impeller is directly mounted on the extended shaft of the motor, resulting in a short axial dimension and a compact structure. The bearings of the pump and the motor are arranged appropriately, which enables effective balancing of the radial and axial loads generated during pump operation; this ensures smooth operation of the pump with low vibration and noise levels. 3. The shaft seal uses a mechanical seal or a combination of mechanical seals; it features imported titanium alloy seal rings, medium-sized high-temperature resistant mechanical seals, as well as wear-resistant seals made of cemented carbide, all of which help to effectively extend the service life of the mechanical seal. 4. It is easy to install and maintain; there is no need to disassemble the piping system – simply remove the nut on the pump coupling seat to extract all the rotor components. 5. The pumps can be operated in series or parallel according to the usage requirements, namely the needs for flow rate and head. 6. The pump can be installed vertically or horizontally, depending on the requirements of the pipeline layout. Most common faults and analysis of single-stage centrifugal pumps: Common faults, Causes of faults, Solutions: ① No liquid discharge – The impeller or inlet valve is blocked by foreign objects ； The liquid absorption height is too high ； Air leaking into the suction line ； The pump is not filled with liquid ； The temperature of the liquid being transported is too high ； The outlet valve or inlet valve will not open due to damage; remove foreign objects ； Reduce the liquid absorption height ； Tighten loose bolts or replace the gasket ； Stop the pump and fill with liquid ； Lower the liquid temperature or reduce the installation height ； Replace or repair the valve. ② Insufficient flow rate; impeller rotating in reverse direction ； The impeller or inlet valve is blocked ； The impeller is corroded and severely worn ； The inlet seal ring is excessively worn ； The liquid level in the reservoir has dropped too much, resulting in an excessive suction height ； Air enters the pump body or suction pipeline, changing the direction of flow ； Remove the blockage ； Replace or repair the impeller ； Replace the population seal ring ； Increase the liquid level in the reservoir ； Tighten to improve sealing. ③ Abnormal noise: Foreign objects have entered the pump body ； The impeller back cap has fallen off ； Friction between the impeller and the pump casing ； Damage to rolling bearings ； Remove foreign objects caused by friction between the filler gland and the pump shaft or sleeve ； Retighten or replace the impeller back cap ； Adjust the thickness of the pump cover gasket or the thickness of the shimming material for bearing gland, and replace the rolling bearings ； Tighten the packing gland symmetrically and evenly. ④ Bearing overheating, centerline deviation ； Lack of oil or excessive impurities in the oil ； Bearing damage ； The bearing hole in the pump body is worn, causing the outer ring of the bearing to rotate and generating frictional heat ； The bearing cover is tightened too much; there is no clearance inside the bearing. Align the axis ； Clean the bearings, lubricate or change the oil ； Replace the bearing ； Replace the pump body or repair the bearing hole ； Increase the thickness of the gland gasket. ⑤ Frequent leakage from the packing seal – not enough rings of packing have been installed ； The method of filling the filler is incorrect ； The type or specification of filler used is inappropriate ； The filler gland is not tightened properly ； The radial clearance between the inner hole of the pump body and the pump shaft is too large, resulting in damage to the sealing packing; additional packing should be installed ； Refill material ； Replace the packing and reinstall it ； Tighten the gland nut properly ； Reduce the radial clearance. Single-stage centrifugal pumps have a relatively simple structure; be sure to pay attention to operational safety in case of failures.