How should the explosion protection rating of electrical equipment be chosen?
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How should the explosion protection rating of electrical equipment be chosen? Normally, Exd II B T4 is the choice. So in what situations is it necessary to opt for a higher level of explosion protection, such as Exd II C T6?
It is determined based on combustible gases; it is explained in GB50058 – take a look and you’ll understand
It depends on what the material is; the specific criteria need to be checked
Everything said above is correct; when the materials are more hazardous, a higher explosion-proof rating is required. For substances such as hydrogen, acetylene, and carbon disulfide, which are commonly used, an IIC rating is necessary
The design institute will select the appropriate explosion protection rating based on the type of gases present at the site to meet the requirements
Definition of explosion-proof rating: Explosion-proof equipment refers to electrical devices that will not cause ignition in the surrounding explosive environment under specified conditions. It is divided into three categories. Category I: Electrical equipment used in coal mines ； Class II: All electrical equipment for explosive gas environments other than coal mines and underground areas. Category II can be further divided into IIA, IIB, and IIC; devices designated as IIB can be used under the same conditions as IIA devices ； ⅡC can be applied under the same conditions as ⅡA and ⅡB. Class III: Electrical equipment for explosive dust environments other than coal mines. Class IIIA: Flammable fluff ； Class IIIB: Non-conductive dust ； Class IIIC: Conductive dust. Maximum surface temperature: The highest temperature reached by any component of an electrical equipment that could cause ignition in an explosive environment surrounding it, when the equipment is operating under the most unfavorable conditions within its specified range. The maximum surface temperature should be below the flammability temperature. For example: if the ignition temperature of the explosive gases in the environment surrounding the explosion-proof sensor is 100°C, then under the most severe operating conditions, the highest surface temperature of any component of the sensor should be below 100°C. Temperature categories: Electrical equipment for explosive environments is classified into groups T1–T6 based on its maximum surface temperature. T1 T2 T3 T4 T5 T6 450 ℃ 300 ℃ 200℃ 135 ℃ 100 ℃ 85℃
First, it is necessary to define the conditions of the emission source through process design; thereafter, the appropriate classification level is selected based on the physical properties of the medium from which the emissions originate. For details, refer to GB50058
#Here’s a quick reply: #It depends on what material it is; the specific criteria need to be checked
The explosion protection rating is determined based on the hazardous substances that may be present in the process flow at the site. If the hazardous gas present is of type II B T4, then there is no difference between choosing Exd II B T4 or Exd II C T6 equipment; choosing the latter at a higher cost would simply represent a waste of resources. If the hazardous gas at the site is II C T6, only the latter can be chosen. The on-site explosion protection level is determined by the design institute based on the potential sources of release in the process; the gas classification data provided in Appendix A of GB3836.11-2017 can be used as a reference (the domestic design standard GB50058-2014 can also be consulted). The explosion protection level at the site has been determined, and equipment selection can also be carried out in accordance with GB3836.15.