Classification of explosion-proof grade and introduction of relevant parameters


Release time:

2022-02-14

Definition of Intrinsically Safe Equipment Marking Ex-Explosion-proof mark ia-explosion-proof class Ga-Equipment protection class Ⅱ C- gas group a Ga]Ⅱ C. The company's products explosion-proof level:[Ex ia Ga]Ⅱ C. Explosion-proof grade ia: The explosive gas mixture cannot be ignited under normal operation, one count failure and two count failures. The intrinsically safe end of the safety barrier of this level can be connected to the intrinsically safe equipment in the hazardous areas of Zone 0, Zone 1 and Zone 2. Class "ia" electrical equipment must adopt a "triple" design for components that are susceptible to interference. ib: The explosive gas mixture cannot be ignited under normal operation and one count failure. The intrinsically safe end of the safety barrier can be connected to the intrinsically safe equipment in Zone 1 and Zone 2 hazardous locations. Class "ib" electrical equipment must be dually designed for components susceptible to interference. IC: under normal working conditions can not ignite explosive gas mixture. The intrinsically safe end of the safety barrier of this rating can be connected to the intrinsically safe equipment in the hazardous area of Zone 2. Gas Group Group I electrical equipment: used in coal mine environments susceptible to methane. Group II electrical equipment: can be used in explosive hazardous environments except coal mines. Group II electrical equipment can be further subdivided according to the different ignition energy of flammable substances. Each subgroup is distinguished by capital English letters. As can be seen from the following table, group ⅡC requires the least ignition energy, that is, in this group of electrical equipment, group ⅡC equipment has versatility for groups ⅡA and ⅡB. Temperature Class The equipment temperature class specifies the maximum allowable temperature value of the equipment surface. The temperature level of the equipment must be less than the ignition temperature of the combustible material used in the dangerous place environment, otherwise it will cause combustion and explosion. As can be seen from the above table, the vast majority of common explosive gases belong to the temperature group above T4. Zone division of explosive hazardous locations In the design of safety explosion-proof system and the selection of explosion-proof products, in addition to the need to classify and group the gases existing in the explosive environment, the area division of explosive gas dangerous places should be carried out according to the frequency and duration of explosive gas occurrence: The company's ia class II C gas group products are suitable for zone 0, zone 1 and zone 2 at the same time. Safety barrier intrinsically safe performance certification parameters Maximum voltage (Um) The highest voltage (AC effective value or DC voltage value) that can be applied to the non-energy-limiting connection device of the associated equipment without invalidating the explosion-proof type. Maximum input voltage (Ui) The highest voltage (AC peak or DC) applied to an intrinsically safe circuit connection without invalidating the intrinsically safe performance. Maximum output voltage (Uo) The highest output voltage (AC peak or DC) of an intrinsically safe circuit that may occur under open circuit conditions when the maximum voltage (including Um and Ui) is applied to the equipment connection device. Maximum input current (Ii) The maximum current (AC peak or DC) applied to the intrinsically safe circuit connection device without disabling the intrinsically safe performance. Maximum output current (Io) The maximum current (AC peak or DC) from the intrinsically safe circuit of the electrical equipment connection device. Maximum input power (Pi) The maximum input power of an intrinsically safe circuit that may be consumed inside an electrical device when the connection of the electrical device to an external power source does not disable the intrinsically safe performance. Maximum output power (Po) The maximum output power of an intrinsically safe circuit that can be obtained from electrical equipment. Maximum internal capacitance (Ci) The total equivalent internal capacitance of the electrical equipment that occurs through the electrical equipment connection device. Maximum external capacitance (Co) The maximum capacitance of an intrinsically safe circuit that can be connected to an electrical equipment connection device without disabling the intrinsically safe performance. Maximum internal inductance (Li) The total equivalent internal inductance of the electrical equipment through the electrical equipment connection device. Maximum external inductance (Lo) The maximum inductance of an intrinsically safe circuit that can be connected to an electrical equipment connection device without disabling the intrinsically safe performance. Maximum allowable distributed capacitance of cable The difference between the maximum external capacitance (Co) allowed by the associated device and the maximum internal capacitance (Ci) of the intrinsically safe device. Maximum allowable distributed inductance of cable (Lc) The difference between the maximum allowable external inductance (Lo) of the associated equipment and the maximum internal inductance (Li) of the intrinsic safety equipment. Maximum external inductor-resistance ratio (Lo/Ro) The ratio of the inductance to the resistance of the external circuit that can be connected to the electrical equipment connection device without causing the intrinsic safety performance to fail. Most of the industrial developed countries in the world adopt the way of "parameter authentication", that is, a set of safety parameters are given to the associated equipment and field equipment, and the user can freely combine the electrical equipment of different manufacturers, from the perspective of safety, only need to meet the following relationship: Selection principle of safety barrier a) Determine the explosion-proof level of the required safety barrier according to the type of hazardous site and the explosion-proof requirements on site. The explosion-proof level of the safety barrier must not be lower than the explosion-proof mark level of the intrinsically safe field equipment; B) Provide corresponding safety barriers according to the type of equipment on site; c) Determine the maximum voltage of the safety barrier according to the maximum voltage that may exist or be generated by the instrument in the control room; d) Determine the polarity of the safety barrier according to the signal of the field device and the polarity of the power supply to the ground; the safety barrier shall be matched with the safety polarity and signal transmission mode of the on-site instrument. e) Considering the influence of the resistance voltage drop at the end of the safety barrier, determine the maximum short-circuit current of the safety barrier and whether the system can work normally; f) Whether the allowable distribution parameters of the safety barrier meet the requirements.

Definition of Intrinsically Safe Equipment Marking

Ex-Explosion-proof mark

ia-explosion-proof class

Ga-Equipment protection class

Ⅱ C- gas group a Ga]Ⅱ C.

 

 

The company's products explosion-proof level:[Ex ia Ga]Ⅱ C.

 

 

Explosion-proof grade

ia: The explosive gas mixture cannot be ignited under normal operation, one count failure and two count failures. The intrinsically safe end of the safety barrier of this level can be connected to the intrinsically safe equipment in the hazardous areas of Zone 0, Zone 1 and Zone 2. Class "ia" electrical equipment must adopt a "triple" design for components that are susceptible to interference.

 

ib: The explosive gas mixture cannot be ignited under normal operation and one count failure. The intrinsically safe end of the safety barrier can be connected to the intrinsically safe equipment in Zone 1 and Zone 2 hazardous locations. Class "ib" electrical equipment must be dually designed for components susceptible to interference.

ic: Can not ignite explosive gas mixture under normal working conditions. The intrinsically safe end of this level of barrier can be connected to intrinsically safe equipment in a Zone 2 hazardous location.

 

Gas Group

Group I electrical equipment: used in coal mine environments susceptible to methane.

Group II electrical equipment: can be used in explosive hazardous environments other than coal mines.

Group II electrical equipment can be further subdivided according to the different ignition energy of flammable substances. Each subgroup is distinguished by capital English letters. As can be seen from the following table, group ⅡC requires the least ignition energy, that is, in this group of electrical equipment, group ⅡC equipment has versatility for groups ⅡA and ⅡB.

南京帕罗肯科技有限公司

Temperature Class

The equipment temperature class specifies the maximum allowable temperature value of the equipment surface. The temperature level of the equipment must be less than the ignition temperature of the combustible material used in the dangerous place environment, otherwise it will cause combustion and explosion.

南京帕罗肯科技有限公司

As can be seen from the above table, the vast majority of common explosive gases belong to the temperature group above T4.

 

Zone division of explosive hazardous locations

In the design of safety explosion-proof system and the selection of explosion-proof products, in addition to the need to classify and group the gases existing in the explosive environment, the area division of explosive gas dangerous places should be carried out according to the frequency and duration of explosive gas occurrence:

南京帕罗肯科技有限公司

 

The company's ia class II C gas group products are suitable for zone 0, zone 1 and zone 2 at the same time.

 

Safety barrier intrinsically safe performance certification parameters

Maximum voltage (Um)

The highest voltage (AC effective value or DC voltage value) that can be applied to the non-energy-limiting connection device of the associated equipment without invalidating the explosion-proof type.

Maximum input voltage (Ui)

The highest voltage (AC peak or DC) applied to an intrinsically safe circuit connection without invalidating the intrinsically safe performance.

Maximum output voltage (Uo)

The highest output voltage (AC peak or DC) of an intrinsically safe circuit that may occur under open circuit conditions when the maximum voltage (including Um and Ui) is applied to the equipment connection device.

Maximum input current (Ii)

The maximum current (AC peak or DC) applied to the intrinsically safe circuit connection device without disabling the intrinsically safe performance.

Maximum output current (Io)

The maximum current (AC peak or DC) from the intrinsically safe circuit of the electrical equipment connection device.

Maximum input power (Pi)

The maximum input power of an intrinsically safe circuit that may be consumed inside an electrical device when the connection of the electrical device to an external power source does not disable the intrinsically safe performance.

Maximum output power (Po)

The maximum output power of an intrinsically safe circuit that can be obtained from electrical equipment.

 

Maximum internal capacitance (Ci)

The total equivalent internal capacitance of the electrical equipment that occurs through the electrical equipment connection device.

Maximum external capacitance (Co)

The maximum capacitance of an intrinsically safe circuit that can be connected to an electrical equipment connection device without disabling the intrinsically safe performance.

Maximum internal inductance (Li)

The total equivalent internal inductance of the electrical equipment through the electrical equipment connection device.

Maximum external inductance (Lo)

The maximum inductance of an intrinsically safe circuit that can be connected to an electrical equipment connection device without disabling the intrinsically safe performance.

Maximum allowable distributed capacitance of cable

The difference between the maximum external capacitance (Co) allowed by the associated device and the maximum internal capacitance (Ci) of the intrinsically safe device.

Maximum allowable distributed inductance of cable (Lc)

The difference between the maximum allowable external inductance (Lo) of the associated equipment and the maximum internal inductance (Li) of the intrinsic safety equipment.

Maximum external inductor-resistance ratio (Lo/Ro)

The ratio of the inductance to the resistance of the external circuit that can be connected to the electrical equipment connection device without causing the intrinsic safety performance to fail.

 

 

Most of the industrial developed countries in the world adopt the way of "parameter authentication", that is, a set of safety parameters are given to the associated equipment and field equipment, and the user can freely combine the electrical equipment of different manufacturers, from the perspective of safety, only need to meet the following relationship:

南京帕罗肯科技有限公司

Selection principle of safety barrier

a) Determine the explosion-proof level of the required safety barrier according to the type of hazardous site and the explosion-proof requirements on site. The explosion-proof level of the safety barrier must not be lower than the explosion-proof mark level of the intrinsically safe field equipment;

 

B) Provide corresponding safety barriers according to the type of equipment on site;

 

c) Determine the maximum voltage of the safety barrier according to the maximum voltage that may exist or be generated by the instrument in the control room;

 

d) Determine the polarity of the safety barrier according to the signal of the field device and the polarity of the power supply to the ground; the safety barrier shall be matched with the safety polarity and signal transmission mode of the on-site instrument.

 

e) Considering the influence of the resistance voltage drop at the end of the safety barrier, determine the maximum short-circuit current of the safety barrier and whether the system can work normally;

 

f) Whether the allowable distribution parameters of the safety barrier meet the requirements.