Leak testing of HEPA filters

Formaldehyde (Class VI Hazardous Chemicals)
Chemical formula HCHO, formula 30.03, also known as ant aldehyde. Colorless gas, with a special odor, irritating to the eyes, nose, etc., gas relative density 1.067 (air = 1), liquid density 0.815g/cm3 (-20 ℃). Melting point -92℃, boiling point -19.5℃. Soluble in water and ethanol. The concentration of the aqueous solution can reach up to 55%, usually 40%, called as formaldehyde water, commonly known as formalin (formalin), is a colorless liquid with a pungent odor.

It has a strong reducing effect, especially in alkaline solutions. Can burn, vapor and air to form explosive mixtures, the explosion limit of 7% -73% (volume). The ignition temperature is about 300℃. The product is a strong reducing agent, more reducing in trace alkaline. It can be slowly oxidized to formic acid in air.
Formaldehyde can be produced by dehydrogenation or oxidation of methanol catalyzed by silver, copper and other metals, and can also be separated from hydrocarbon oxidation products. Used as pesticide and disinfectant, raw material for phenolic resin, urea-formaldehyde resin, vinylon, urotropin, pentaerythritol and dyes.
Soluble in water and ether. The concentration of water solution can be up to 55%. It is freely miscible with water, ethanol and acetone. It can be gradually oxidized to formic acid in air and is a strong reducing agent. Its vapor and air to form explosive mixtures, meet open flame, high heat can cause combustion and explosion.
Industrial formaldehyde solution generally contains 37% formaldehyde and 15% methanol, as a polymerization inhibitor, boiling point 101 ℃.
Acetaldehyde (Class VI Dangerous Goods)
(acetaldehyde) is a kind of aldehyde, also known as acetaldehyde, colorless and easy to flow liquid, with irritating odor. Melting point-121℃, boiling point 20.8℃, relative density less than 1.
Mutually soluble with water and ethanol and other organic substances.
Flammable and volatile, vapor and air can form explosive mixtures, explosion limit 4.0% to 57.0% (volume).

Mutually soluble with water, ethanol, ether, chloroform and so on.
Propionaldehyde (Class VI Dangerous Goods)
Normally colorless flammable liquid. It is irritating. Soluble in water, miscible with ethanol and ether. Used to make synthetic resin, rubber accelerator and antioxidant. Also used as antifreeze, lubricant and dehydrating agent. Mainly synthesized from ethylene by carbonyl synthesis, can also be oxidized with dichromate of n-propanol or n-propanol vapors at high temperature through a copper catalyst and produced. Flammable, its vapor and air can form explosive mixtures, when exposed to open flame, high heat is very easy to burn and explode. It reacts violently with oxidizer. If it meets high heat, polymerization reaction can occur, releasing a large amount of heat and causing the container.

Dimethyl ether (methyl ether) (Class II hazardous chemicals)
It is a colorless gas with a slight ether aroma.
Methyl ether is dissolved in heavy oil inert, non-carcinogenic but neurotoxic. Also has excellent miscibility, can be miscible with most polar and non-polar organic solvents. In 100 ml of water can dissolve 3.700 ml of dimethyl ether gas, and dimethyl ether is soluble in gasoline, carbon tetrachloride, acetone, chlorobenzene and methyl acetate and other organic solvents, adding a small amount of additives can be soluble with water at any ratio. The flame is slightly bright when it burns.
Molecular formula C2H6O Molecular weight 46.07 Molar mass 46.07 Vapor pressure (20℃) 0.51Mpa
Melting point -138.5℃ Heat of combustion of gas 28.8MJ/Kg
Boiling point -24.9℃ Heat of vaporization (-20℃) 410KJ/Kg
Critical temperature 127℃ Auto-ignition temperature 235℃ Liquid density (20℃) 0.67Kg/L Explosion limit, air 3~17vol%
Vapor Density 1.61Kg/m3 Flash Point -41℃ (Air Density 1.2936Kg/m3)[1]
DME is a colorless, tasteless, odorless gas at room temperature and pressure, and a liquid under pressure, with properties similar to liquefied petroleum gas (LPG).