Problems that should be paid attention to when selecting chemical pumps
Pay attention to the selection of chemical pumps
Corrosion resistance problem
Corrosion has always been one of the most headache hazards of chemical equipment. A little carelessness can damage the equipment, or cause an accident or even a disaster. According to relevant statistics, about 60% of the damage of chemical equipment is caused by corrosion. Therefore, when selecting a chemical pump, it is necessary to pay attention to the scientific nature of material selection. There is usually a misunderstanding that stainless steel is a "universal material". It is very dangerous to use stainless steel regardless of the medium and environmental conditions. Here are some key points of material selection for some common chemical media:
1. Sulfuric acid
As one of the strong corrosive media, sulfuric acid is an important industrial raw material with a wide range of uses.
2. Hydrochloric acid
Most metal materials are not resistant to hydrochloric acid corrosion (including various stainless steel materials), and high-silicon ferro-molybdenum can only be used in hydrochloric acid below 50°C and 30%. Contrary to metal materials, most non-metal materials have good corrosion resistance to hydrochloric acid, so rubber pumps and plastic pumps (such as polypropylene, fluoroplastics, etc.) are the best choice for transporting hydrochloric acid. The company's applicable products include: IHF lined fluorine pump, PF (FS) strong corrosion-resistant centrifugal pump, CQ polypropylene magnetic pump (or fluorine plastic magnetic pump), etc.
3. Nitric acid
Most metals are quickly corroded and destroyed in nitric acid. Stainless steel is the most widely used nitric acid resistant material. It has good corrosion resistance to all concentrations of nitric acid at room temperature. It is worth mentioning that stainless steels containing molybdenum (such as 316, 316L) ) The corrosion resistance to nitric acid is not better than ordinary stainless steel.
4. Acetic acid
It is one of the most corrosive substances in organic acids. Ordinary steel will be severely corroded in acetic acid at all concentrations and temperatures. Stainless steel is an excellent acetic acid resistant material. 316 stainless steel containing molybdenum is also suitable for high temperature and dilute acetic acid vapor. . For harsh requirements such as high temperature and high concentration of acetic acid or containing other corrosive media, high alloy stainless steel or fluoroplastic pumps can be used.
5. Alkali (sodium hydroxide)
Steel is widely used in sodium hydroxide solution with a concentration of 30% below 80℃, and many factories still use ordinary steel at 100℃ below 75%. Although corrosion increases, it is economical. The corrosion resistance of ordinary stainless steel to lye has no obvious advantages compared with cast iron. As long as a small amount of iron is allowed to be mixed in the medium, stainless steel is not recommended. For high-temperature lye, titanium and titanium alloy or high-alloy stainless steel are mostly used. The company's general cast iron pumps can be used for low-concentration lye at room temperature, and various stainless steel pumps or fluoroplastic pumps can be used for special requirements.
6. Ammonia (Ammonia Hydroxide)
Most metals and non-metals have slight corrosion in liquid ammonia and ammonia (ammonia hydroxide). Only copper and copper alloys are not suitable for use. Most of the company's products are suitable for the transportation of ammonia and ammonia.
7. Salt water (sea water)
Ordinary steel has a low corrosion rate in sodium chloride solution, seawater and salt water, and generally must be protected by paint; all kinds of stainless steel also have a very low uniform corrosion rate, but may cause local corrosion due to chloride ions, usually 316 stainless steel better. All kinds of chemical pumps of the company have 316 material configuration.
8. Alcohols, ketones, esters, ethers
Common alcohol media include methanol, ethanol, ethylene glycol, propanol, etc., ketone media include acetone, butanone, etc., ester media include various methyl and ethyl esters, and ether media include methyl ether, ethyl ether, Butyl ether, etc., they are basically non-corrosive, and common materials can be applied. When selecting, a reasonable choice should be made according to the properties of the medium and related requirements. It is also worth noting that ketones, esters, and ethers are soluble in a variety of rubbers, so errors should be avoided when selecting sealing materials.
