Liquid chlorine plant

Basic principles of explosion protection. The concept of explosion: An explosion occurs when a substance, through physical or chemical changes, suddenly changes from one state to another, releasing enormous amounts of energy. The energy released from such rapid speed will cause intense impact and damage to the objects around it. Three conditions that must be present for an explosion: 1) Explosive material: a substance that can react with oxygen (air), including gases, liquids, and solids. (Gases: hydrogen, acetylene, methane, etc.) ； Liquids: alcohol, gasoline ； Solids: dust, fibrous dust, etc. ) 2 ) Oxygen: Air. 3) Ignition sources: include open flames, electrical sparks, mechanical sparks, static electricity sparks, high temperatures, chemical reactions, light energy, etc. Why is explosion protection needed? Flammable substances: Many production sites generate certain flammable materials. About two-thirds of coal mine sites have explosive materials present ； In the chemical industry, explosive substances are present in over 80% of the production facility areas. Oxygen: Oxygen is present everywhere in the air. Ignition sources: During the production process, electrical instruments are used in large quantities, and electrical sparks from various types of friction, sparks resulting from mechanical wear, static electricity sparks, and high temperatures are inevitable, especially when the instruments or electrical equipment malfunction. Objectively, many industrial sites meet the conditions for explosions. When the concentration mixture of explosive substances and oxygen is within the explosive range, an explosion will occur if there is an ignition source. Therefore, it is necessary to adopt explosion protection. Principle of instrument explosion protection. Classification of hazard levels in hazardous areas: Explosive substances. Definition of zones. Chinese standards. North American standards. Zone 0: Div.1 Gases (CLASS I) – Areas where explosive gas mixtures are present continuously or for extended periods under normal conditions. Zone 1: Areas where explosive gas mixtures may occur under normal conditions. Zone 2: Div.2 – Areas where explosive gas mixtures cannot occur under normal conditions, but may appear occasionally or for short periods only under abnormal conditions. Zone 10: Div.1 – Dusts or fibers (CLASS II/III) – Areas where explosive dusts or combustible fibers mixed with air may be present continuously, frequently for short periods, or for extended periods under normal conditions. Zone 11: Div.2 – Areas where explosive dusts or combustible fibers mixed with air cannot occur under normal conditions, but may appear occasionally or for short periods only under abnormal conditions. Applicability of explosion protection methods to hazardous areas: Serial number. Explosion protection type. Code. Standard. Explosion protection measures. Applicable zones. 1. Flameproof type. d. GB3836.2 – Isolating ignition sources. Zones 1 and 2. 2. Increased safety type. e. GB3836.3 – Preventing the generation of ignition sources. 3. Intrinsic safety type. ia. GB3836.4 – Limiting the energy of ignition sources. Intrinsic safety type ib. GB3836.4 – Limiting the energy of ignition sources. 4. Positive pressure type. p. GB3836.5 – Separating hazardous substances from ignition sources. Zones 1 and 2. 5. Immersed oil type. o. GB3836.6 – Separating hazardous substances from ignition sources. 6. Sand-filled type. q. GB3836.7 – Separating hazardous substances from ignition sources. Zones 1 and 2. 7. Spark-free type. n. GB3836.8 – Preventing the generation of ignition sources. Zone 2. 8. Sealed type. m. GB3836.9 – Preventing the generation of ignition sources. 9. Hermetically sealed type. h. GB3836.10 – Preventing the generation of ignition sources. Zones 1 and 2. Classification of explosive gases: Based on the minimum spark energy required to initiate an explosion, China, Europe, and most other countries and regions classify explosive gases into four hazard levels, as shown in the table below: Operating condition category. Gas classification. Representative gases. Minimum ignition spark energy. Underground mines: Class I – Methane, 0.280 mJ. Factories outside mines: Class IIA – Propane, 0.180 mJ. Class IIB – Ethylene, 0.060 mJ. Class IIC – Hydrogen, 0.019 mJ. The United States and Canada first classified explosive substances dispersed in air into three classes: CLASS I gases and vapors; CLASS II dusts; CLASS III fibers. Gases and dusts were then further divided into groups: Group name. Representative gases or dusts. A – Acetylene. B – Hydrogen. C – Ethylene. D – Propane. E – Metal dusts. F – Coal dusts. Grain dusts. Classification of gas temperature groups: Temperature group. Safe surface temperature of objects. Common explosive gases: T1 ≤ 450°C – Hydrogen, acrylonitrile, etc., 46 types. T2 ≤ 300°C – Acetylene, ethylene, etc., 47 types. T3 ≤ 200°C – Gasoline, butyraldehyde, etc., 36 types. T4 ≤ 135°C – Acetaldehyde, tetrafluoroethylene, etc., 6 types. Temperature group T6 – Instrument surface temperature not exceeding 85°C. Meaning of Ex(ia)IIC: Marking content. Symbol. Meaning. Explosion protection declaration. Ex – Complies with European explosion protection standards. Explosion protection method. ia – Uses ia-level intrinsic safety protection method; can be installed in Zone 0. Gas category. IIIC – Permitted to operate in environments with IIIC-class explosive gases. Note: The absence of a temperature group item in this marking indicates that the instrument does not come into direct contact with explosive gases. Explosion protection terms: Maximum allowable voltage of the safety barrier: Um – The highest voltage that can be applied to the intrinsically safe side of the safety barrier while maintaining its intrinsically safe properties. Last edited by minous on 2009-3-13 at 11:14

If there is only liquid chlorine in this factory, liquid chlorine itself poses little risk of explosion, so there is no need for explosion-proof measures; however, it is still necessary to install fire alarm systems.

The electrical system in the liquid chlorine plant is primarily designed to prevent corrosive gases from entering the electrical components. Airtightness is required.

In my opinion, it is not explosion-proof; there’s no way to specify an explosion protection rating either, as such information cannot be found