Chemical pump delivery of acid and alkali how to determine the material

Chemical pump in many run under complex working environment, the most prominent problem is the chemical pump corrosion resistance, in the face of all kinds of complicated conditions, using the chemical pump must communicate with manufacturers make timely and comprehensive, for some commonly used chemical medium, material selection of chemical pump do some simple introduction, convenient for user selection:

1. Sulfuric acid is one of the highly corrosive media, and sulfuric acid is an important industrial raw material with a wide range of USES.

Corrosion of different concentration and temperature of sulfuric acid on the material difference is bigger, the concentration is above 80%, the temperature is less than 80 ℃ concentrated sulfuric acid, carbon steel and cast iron has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, is not used as a pump valve materials;

Ordinary stainless steels such as 304 (0Cr18Ni9) and 316 (0Cr18Ni12Mo2Ti) have limited use for sulfuric acid medium.

Therefore, the pump valve for conveying sulfuric acid is usually made of high-silicon cast iron (difficult to cast and process) and high-alloy stainless steel (no. 20 alloy).

Fluorine plastics have better resistance to sulfuric acid and the use of fluorine pump (F46) is a more economical choice.

2, hydrochloric acid, most don't hydrochloric acid corrosion resistant metal materials (including all kinds of stainless steel materials), also can only be used for high silicon molybdenum 50 ℃ and below 30% hydrochloric acid.

In contrast to metallic materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so lining rubber pumps and plastic pumps (such as polypropylene, fluoroplast, etc.) is the best choice for conveying hydrochloric acid.

3, nitric acid general metal corrosion and damage, mostly in nitric acid was quickly is the most widely used nitric acid resistant stainless steel material, all on room temperature the concentration of nitric acid have good corrosion resistance, it is important to note that the molybdenum stainless steel (e.g., 316, 316 l) of nitric acid corrosion resistance not only no better than ordinary stainless steel (e.g., 304, 321), sometimes even less.

For high temperature nitric acid, usually titanium and titanium alloy materials are used.

4. Acetic acid is one of the most corrosive substances in organic acids. Ordinary steel will be severely corroded in acetic acid of all concentrations and temperatures.

For high temperature and high concentration acetic acid or other corrosive medium, high alloy stainless steel pump or fluorine plastic pump can be used.

5, alkali (sodium hydroxide) steel is widely used in under 80 ℃, 30% concentration of sodium hydroxide solution, there are also many factory under 100 ℃, 75% still USES the ordinary steel, while the corrosion increases, but the economy better.

The corrosion resistance of ordinary stainless steel to alkali liquor has no obvious advantage compared with that of cast iron. It is not recommended to use stainless steel as long as a small amount of iron is allowed in medium.

For high-temperature alkali liquor, titanium and titanium alloy or high alloy stainless steel are mostly used.

Ammonia (ammonia hydroxide) most metals and nonmetals corrode very slightly in liquid ammonia and ammonia water (ammonia hydroxide), and only copper and copper alloys are not suitable for use.

7. The corrosion rate of ordinary steel in salt water (seawater) is not too high in sodium chloride solution, seawater and salt water. Generally, it shall be protected by coating.

All kinds of stainless steels also have very low uniform corrosion rate, but may cause local corrosion because of chloride ion, 316 stainless steels are usually better.

8, alcohols, esters, ketones, ethers, common alcohol medium such as methanol, ethanol, ethylene glycol, propylene glycol, ketone medium such as acetone, butanone, there are all kinds of methyl esters medium, ethyl ester, ethers media such as methyl ether, ethyl ether, butyl ether, their basic no corrosive, commonly used materials are applicable, the specific selection should also according to the requirements of the dielectric properties and related make reasonable choice.

It is also worth noting that ketones, esters and ethers are soluble to a variety of rubber, and errors are avoided when choosing sealing materials.

Yamei group has made some simple summaries, complicated working conditions are countless. For users, the best selection method is to hand over to the manufacturer for selection. If users have any doubts about the selection of chemical pump, please feel free to communicate with us and we will give you the most professional solutions.