How to Define the Medium in the Process Parameters of the Pressure Vessel?

The medium refers to the material contained in the pressure vessel, in liquid, gaseous or gas-liquid mixed state. The safety of pressure vessels is closely related to the media contained in them. The nature of the media is different, and the requirements for the material, manufacture and use of the container are also different. The media have flammable, explosive, corrosive and toxic containers, which should be paid attention to when in use and maintainance.

(1) Toxic media.
Refer to GBZ230 "Classification of Hazard Degree of Occupational Exposure to Toxic Substances" to classify toxic media into four levels, specifically:
LevelⅠ: Extremely hazardous, Allowable concentration <0.1mg/m3;
Level Ⅱ: Highly hazardous, Allowable concentration 0.1~<1.0mg/m3 ;
Level Ⅲ: Moderate hazardous, Allowable concentration 1.0~<10mg/m3.
Level Ⅳ: Mild Hazardous, Allowable concentration ≥10mg/m3.
 
(2) Flammable media.
Refers to gas mixed with air with a lower explosion limit of less than 10%, or a difference between the upper and lower explosion limits of more than 20%.

(3) Mixed media.
When the medium in the pressure vessel is a mixed substance, the composition of the medium and the principle of division of toxicity and flammable medium should be determined by the process design of the design unit or the production technology department of the user unit to determine whether the medium is toxic or belongs to a flammable medium. 

(4) Corrosive media.
Such as nitric acid, sulfuric acid, hydrochloric acid, naphthenic acid, strong alkali, etc. are highly corrosive. The media is very corrosive, the types and properties of the media are different, and the process conditions are different, so as the media corrosive property.