【Test Center 4】Management of major hazard sources of hazardous chemicals
1. Unit
(1) Production unit: the equipment and facilities for the production, processing and use of hazardous chemicals, when there is a shut-off valve between the device and the facility, the shut-off valve is used as the separation boundary and divided into independent units.
(2) Storage unit: a relatively independent area composed of tanks or warehouses used to store hazardous chemicals, the storage tank area is divided into independent units by the tank farm fire embankment, and the warehouse is divided into independent units by the boundary of independent warehouses (independent buildings).
2. Critical quantity
The name of the hazardous chemical and its critical scale
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When there are many kinds of hazardous chemicals in the production unit and storage unit, the following formula is calculated, and if the formula is satisfied, it is designated as a major hazard source:
式中 q1，q2，… qn—每种危险化学品实际存在量，t；
Q1，Q2，… Qn—与每种危险化学品相对应的临界量，t
Classification criteria for major hazards
Based on the calculated R-values, the following table determines the level of significant hazard sources for hazardous chemicals.
Correspondence between the level of a significant hazard and the R-value
α—the correction coefficient of the personnel exposed outside the plant area of the major hazard source of the hazardous chemical β1,β2,...,βn—the correction factor corresponding to each hazardous chemical;
Q1, Q2,...,QN - the actual amount of each hazardous chemical, in tons (t);
Q1, Q2,...,Qn—The critical amount corresponding to each hazardous chemical, in tons (t).
Q1, Q2,...,Qn—The critical amount corresponding to each hazardous chemical, in tons (t).
【Test Center 5】Safety production inspection
1. Types of security checks
Periodic, recurrent, seasonal, before and after holidays, comprehensive, special, and employee representatives are irregular
2. The content of the security check
Ideology, system management, hidden dangers, accident handling, rectification, equipment and facilities (production, auxiliary), safety facilities, and operating environment
3. Method
Routine inspection, safety checklist method, instrument inspection and data analysis method
【Test Center 6】Fire and explosion prevention safety technical measures
1. The process of dissipating heat, corrosiveness, dust toxicity and the use of flammable and explosive materials or gases, electromagnetic ionizing radiation is serious, arranged in the downwind direction of the external wall and the plant, separated from other production processes, and the production processes with different hazards should also be isolated from each other. The production processes with the same hazards should be arranged in a centralized (or adjacent) manner. For the local section with serious impact, the smoke exhaust hood can be used for mechanical air supply and exhaust, or airtight measures can be taken.
Casting operation: The molding and core-making section should be arranged on the downwind side of the minimum frequency wind direction in the non-heating season in the centralized heating area, and should be located on the downwind side of the minimum frequency wind direction in the non-centralized heating area.
The casting workshop should be arranged in the building complex of the high-temperature workshop and the power workshop, and built on the downwind side of other production buildings in the factory area that do not release harmful substances.
2. Type of explosion-proof electrical equipment
(1) Class I electrical equipment, used in the gas environment of coal mines.
(2) Class II electrical equipment for use in explosive atmospheres.
(3) Class III electrical equipment. For use in explosive dust atmospheres.
I., II.A, II.B, II.C (minimum ignition current ratio, maximum test safety clearance)
Class III.A: flammable flocculents.
Class III.B: Non-conductive dust.
Class III: Conductive dust.
The EPL of Class I equipment used in explosive atmospheres where methane is present in coal mines is divided into two levels: Ma and Mb. The EPL of Class II equipment used in explosive atmospheres is classified as Ga, Gb and Gc. The EPL of Class III equipment used in explosive dust atmospheres is divided into three levels: Da, Db, and Dc.
Ma、Ga、Da 为很高,Mb、Gb、Db 为高,Gc、Dc 为加强。
Type of explosion-proof electrical equipment for use in explosive atmospheres
（1）Ex d IIB T3 Gb
Indicates that the equipment is an explosion-proof type with a protection class of "D" Gb and is an explosion-proof electrical equipment for use in explosive atmospheres of Group IIB T3.
（2）Ex p ⅢC T120℃ Db IP65
Indicates that the device is a positive pressure type "P" protection class Db, explosion-proof electrical equipment for explosive dust atmospheres with III.C conductive dust, with a maximum surface temperature of less than 120°C and an enclosure protection rating of IP65.
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3. The division of the explosion area should be adjusted according to the ventilation conditions:
(1) When the ventilation is good, the explosion hazard area level can be reduced, but when the ventilation is poor, the explosion hazard area level should be increased.
(2) When local mechanical ventilation is more effective than natural ventilation and general mechanical ventilation in reducing the concentration of explosive gas mixtures, local mechanical ventilation can be used to reduce the level of explosion hazard areas.
(3) In obstacles, pits and dead corners, the level of explosion hazard area should be partially raised.
(4) The use of obstacles such as embankments or walls to limit the diffusion of explosive gas mixtures heavier than air can reduce the scope of the explosion hazard area.