The necessary conditions for explosion and fire caused […]
The necessary conditions for explosion and fire caused by static electricity are: the existence of static electricity; the static electricity has reached the level of discharge; the existence of hazardous locations; the ignition energy of flammable substances is large or the concentration has reached the limit of explosion. The necessary conditions for electrostatic shock to occur are: the presence of static electricity; a state of discharge has been reached.
The necessary condition for preventing production from static electricity is that the amount of static electricity reaches a certain level. The basic conditions for causing electrostatic hazards are: the generation and existence of static electricity; the charging and discharging of objects; the existence of dangerous mixtures of combustible substances. Therefore, effective measures such as reducing the generation of static electricity, guiding and dissipating the existence of static electricity, preventing electrostatic discharge, and controlling the concentration of dangerous mixtures of combustible substances must be taken in accordance with the above basic conditions to prevent the occurrence of static electricity hazards.
Measures for electrostatic hazards include grounding method, leakage method, neutralization method, and process control method. 1. Grounding Grounding is the simplest way to eliminate static hazards. Grounding is mainly used to eliminate static electricity on conductors, and should not be used to eliminate static electricity on insulators. If there is static electricity on the insulator, directly grounding the insulator will easily cause spark discharge. In places where there is a danger of fire and explosion, in order to avoid accidents caused by static sparks, the following grounding measures should be taken: (1) all equipment, storage tanks, storages used to process, store, and transport various flammable liquids, gases and powders The tanks as well as the product conveying equipment, closed transport devices, drainage equipment, mixers, filters, dryers, sublimators, adsorbers, etc. must be grounded. If the bag filter is made of a textile-like article, it can be sewn with wire and grounded. (2) Oxygen, acetylene and other pipelines in the plant area and workshop must be connected into a continuous whole and grounded. All other pipes and equipment that can generate static electricity, such as air compressors, ventilators and air pipes, especially air pipes for local exhaust, must be connected as a continuous unit and grounded. If the pipe is made of non-conductive material, wire should be wound outside or inside the pipe, and the wire should be grounded. Metal joints on non-conductive pipes must also be grounded. (3) Auxiliary equipment or tools such as oil-filling funnel, floating cylinder top, and workbench should be grounded. (4) The oil tank of the automobile shall be provided with a metal chain. The upper end of the chain is connected to the chassis of the oil tanker, and the other end is in contact with the ground. (5) In some dangerous places, in order to reliably ground the rotating shaft, a conductive lubricating oil or a slip ring or carbon brush grounding method can be used. The electrostatic grounding device should be firmly connected and have sufficient mechanical strength, and a grounding device can be used for grounding with other purposes.