The damage of chemical equipment is caused by corrosion in metropolis, and many acid, alkaline and other media in industrial production are corrosive to a certain extent. Corrosive media have an impact on the corrosion effect of chemical equipment. A little carelessness may damage the equipment, or even cause accidents or even disasters. Therefore, the selection of acid and alkali resistant vacuum pump is one of the most headache problems for chemical practitioners. When selecting the acid and alkali resistant vacuum pump, we must pay attention to the selection of materials.
Acid and alkali resistant vacuum pump material selection:
The material of anti-corrosion pump is naturally anti-corrosion material. In long-term corrosive environment, it is recommended to use fluoroplastics or polypropylene plastic material, while stainless steel alloy material will cause corrosion, so it is not recommended to use. The main reason why most acid and alkali resistant pumps can be acid resistant is the material of the pump. Generally, non-metallic materials are used as the flow passage parts of the pump for acid and alkali resistant vacuum pumps, such as “polyethylene, polypropylene, polyperfluoroethylene propylene, etc.” among them, polyperfluoroethylene propylene is one of the best acid resistant materials, which can basically resist the corrosion of any acid medium, known as the king of plastics. To transport aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid of various concentrations and various organic acids, strong acids, strong oxidants, or strong alkali organic solvents of various concentrations, as well as other corrosive gas and liquid medium pipelines, polypropylene (PP) anti-corrosion pump is generally used for acid and alkali, if strong acid and alkali, PVDF anti-corrosion pump is suitable.
PVDF is widely used in petrochemical industry, electronic and electrical industry and fluorocarbon coatings. Due to its good chemical resistance, processability, anti fatigue and creep resistance, PVDF is most commonly used in chemical pumps and is one of the best materials for lined pumps, valves, pipes, pipeline fittings, storage tanks and heat exchangers. Long term use is – 40 ~ 150 ℃. The commonly used temperature is 90 ℃ and the maximum working temperature is 110 ℃. It has good chemical corrosion resistance, high temperature resistance, oxidation resistance and radiation resistance.
Acid and alkali resistant vacuum pump selection factors:
Then we should pay attention to the rationality in the usual selection process. The so-called rational selection of acid and alkali resistant pump is to comprehensively consider the comprehensive technical and economic indicators such as the investment and operation cost of acid and alkali resistant pump unit and acid and alkali resistant pump station, so as to make them conform to the principles of economy, safety and applicability. Specifically, there are the following aspects:
1. It must meet the technical parameter requirements of the anti-corrosion pump, such as flow, Yangcheng, medium, power, temperature, etc., that is to say, the operation time point of the acid and alkali resistant pump (the intersection point of the device characteristic curve and the acid and alkali resistant pump performance curve) is often kept in the high-efficiency section, which saves power and is not easy to damage the parts. It is also necessary to know the site installation mode, production process requirements, etc., and finally select the anti-corrosion pump that meets your actual working conditions.
2. The selected water acid and alkali resistant pump should not only have small volume, light weight, low cost, but also have good characteristics and high efficiency.
3. It has good anti cavitation performance, which can not only reduce the excavation depth of the acid and alkali resistant pump room, but also prevent the water acid and alkali resistant pump from cavitation, so that the operation is stable and the service life is long.
4. According to the selected water acid and alkali resistant pump, acid and alkali resistant pump station is built, with less project investment and low operation cost.
Acid and alkali resistant vacuum pump model:
There are many kinds of acid and alkali resistant vacuum pumps according to their functions, such as: self-priming acid and alkali resistant pump, magnetic acid and alkali resistant pump, vertical acid and alkali resistant pump, acid and alkali resistant centrifugal pump. Different types of pumps have different performances, functions and places of use, which also affect the purchase cost, pump operating conditions and subsequent series of problems. If the specific gravity of acid and alkali is not large, the leakage free magnetic pump can be used, but the ratio of acid and alkali is large, so the motor is generally needed to be replaced, so the economical and applicable centrifugal pump for fluoroplastics chemical industry is more appropriate.
Corrosion resistant fluoroplastics chemical acid and alkali resistant pump has excellent corrosion resistance, wear resistance and sealing performance. The acid and alkali resistant centrifugal pump is characterized by stable operation, advanced and reasonable structure, strict and reliable sealing performance, long-term transportation of strong alkali, strong oxidant, organic solvent, reducing agent and other strong corrosive media under the temperature of – 85 ℃ ~ 200 ℃. The pump body is lined with Fluoroplastic (F46) in the metal shell, and the impeller and pump cover and other overflow parts are all molded by one-time high-temperature molding with fluoroplastic alloy wrapped in metal inserts, When the pump is installed in the state of low tank without bottom valve and siphon bucket, the pump is installed in the upper part of the storage tank, and then the diameter and height of siphon bucket are determined according to the calculated volume and the size of existing materials.
At present, the most advanced external Teflon bellows mechanical seal is adopted for acid and alkali resistant chemical pump, which is characterized by compensating the radial runout of pump shaft, single face external seal, easy loading and unloading, intuitive working state, good corrosion resistance and wear-resistant sealing performance, multi-layer protection, and prolonging the service life of mechanical seal; when transporting the medium containing impurities, it can be matched with single face hard to hard without cooling water (silicon carbide to silicon carbide) mechanical seal, special corrosive media such as strong alkali and hydrofluoric acid are equipped with pressureless sintered silicon carbide seal, so the solid content in the media shall be taken into account when selecting the user.
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