What are the characteristics of ammonia valves?

The main ones are as follows:； 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Chemical formula: NH3. 1. Physical properties: Relative molecular mass is 17.031. Ammonia has a density of 0.7081 g/L under standard conditions. It is highly soluble in water, with a solubility ratio of 1:700. Ammonia has an irritating odor. 2. Chemical properties: (1) Reaction with water: When ammonia dissolves in water, its molecules combine with water molecules through hydrogen bonds to form ammonium hydroxide (NH3•H2O). Ammonium hydroxide can partially ionize into ammonium ions and hydroxide ions; therefore, ammonia solution is weakly basic and can turn phenolphthalein solution red. The reaction of ammonia in water can be expressed as follows: Ammonium monohydrate is unstable and decomposes upon heating to produce ammonia and water. In ammonium hydroxide, there exist three species, three ions, and three equilibria: NH3, NH3•H2O, and H2O ； Ions: NH4+, OH-, H+ ； Three equilibria: NH3+H2O ⇌ NH3•H2O, NH4++OH- ⇌ H2O, H++OH-. Three applications of ammonia water in middle school chemistry experiments: ① Using a glass rod dipped in concentrated ammonia water to detect the presence of gases such as HCl ； ②In the laboratory, it is used to react with aluminum salt solutions to produce aluminum hydroxide ； ③Prepare a silver ammonia solution to detect the presence of aldehyde groups in organic molecules. (2) Reaction with acids: 2NH3 + H2SO4 ===(NH4)2SO4; 3NH3 + H3PO4 ===(NH4)3PO4; NH3 + CO2 + H2O === NH4HCO3. The essence of these reactions is that the lone pair of electrons on the nitrogen atom in ammonia bonds with hydrogen ions in the solution, which have empty orbitals, through coordinate bonds to form ionic crystals. If the reaction takes place in an aqueous solution, the ionic equation is: 8NH3 + 3Cl2 === N2 + 6NH4Cl (the yellow-green color disappears, and white smoke is produced). The actual reaction mechanism is: 2NH3 + 3Cl2 === N2 + 6HCl; NH3 + HCl === NH4Cl. The overall reaction equation is: 8NH3 + 3Cl2 === N2 + 6NH4Cl. Ammonia can be easily compressed into a colorless liquid at room temperature, and it also readily solidifies into a snow-like solid. It is highly soluble in water; under standard conditions, 1 volume of water can dissolve 1200 volumes of ammonia, while at 20°C, 1 volume of water can dissolve 700 volumes of ammonia. The solution is alkaline. Soluble in ethanol and ether. Liquid ammonia is a good polar solvent. Liquid ammonia has a slight ionization effect. Liquid ammonia can dissolve alkali metals to form a dark blue solution; very concentrated alkali metal amine solutions are strong reducing agents. Ammonia is usually very stable. It can decompose into hydrogen and nitrogen at high temperatures. It is reducible; it burns with a yellow flame in pure oxygen, producing nitrogen and water. Under platinum catalysis, it is oxidized to form nitric oxide when heated. Oxygen can be removed from heated copper oxide. At room temperature, ammonia in aqueous solution can be oxidized by many strong oxidizing agents (such as Cl2, H2O2, KMnO4, NaClO, etc.). For example: 3Cl2 + 3NH3 = N2 + 6NH4Cl. Ammonia molecules can undergo substitution reactions; the hydrogen atoms in ammonia molecules can be replaced by other atoms or atomic groups, resulting in a series of ammonia derivatives such as amino group –NH2, imino group =NH, and N≡N. Another form of substitution reaction is the replacement of atoms or groups in other compounds by ammonia, either as an amino group or an imino group; for example: HgCl2 + 2NH3 = Hg(NH2)Cl (mercuric ammonium chloride) + NH4Cl

Our factory generally uses stainless steel valves, mainly because ammonia causes severe corrosion; when selecting such valves, it is important to pay attention to the material and its corrosion resistance.

An important point is to ban copper. This is mainly reflected in the fact that the air connection pipes for the valves should be made of stainless steel, rather than copper pipes. For the internal structure of valves, components such as shaft sleeves should not be made of copper alloys like 17-4PH.

We use SUS304 valves imported from Japan, and the mechanical seals are also entirely imported.

The valve body can be CS, and the internal components can be SS; actually 13Cr% is also acceptable, as long as it does not contain copper

Valves must be copper-free; if it is a globe valve, J41B can also be used. The sealing surface should be made of beryllium copper, but stainless steel is the better choice. Our company has experienced shutdown incidents due to the use of carbon steel valves

Well, the explanations and analyses above are quite reasonable; thank you all.