Requirements to electric equipment of fire-dangerous and explosive rooms
The most probable source of ignition are elekyotrichesky sparks. Therefore electric equipment for fire-dangerous and explosive rooms is chosen special type and the ispolyoneniye, depending on the room class.
For fire-dangerous rooms of all classes from P-I to P-II, the III electric motors and the figurative electrified tool are chosen in the closed or protected execution, elektricheyosky lamps (both stationary, and figurative) - in pyleyonepronitsayemy.
More strict requirements, than for pozhayoroopasny rooms are imposed to electric equipment and lamps of explosive pomeyoshcheniye. They are carried out explosion-proof the following types of execution -
- Blast-tight execution (V) - the cover of the elektrodvigayotel or the lamp is strong and expected pressure, explosion pressure, prevyshayoyushchy by 2-3 times, in it. From junctions of covers the flame should not get into the surrounding vzryvoopasyony environment. For this purpose between flanges do zayozor 0,5, 0,3, 0,2 mm high at explosive mixes sootvetyostvenno of the 1, 2, 3 categories. At the exit from these slots combustible gases are so cooled that cannot ignite the okruzhayoyushchy explosive environment.
- Oil-filled execution (M) - current carrying parts of the elekyotrooborudovaniye (except isolated) are submerged in oil and the possibility of contact between these parts and the explosive environment is excluded.
- Special execution (C) - current carrying parts are placed on Wednesday inert gases, in quartz sand, filling pitches. It is applied in explosive rooms of all classes.
In electric equipment blown under excessive davleyoniy (П) current carrying parts are placed in the closed covers. For their purge use the pure air or inert gases.
Intrinsically safe (And) - such execution when energy of the sparks arising in the electric circuit is less than energy, neobkhodiyomy for mix ignition (energy of ignition). Sparks cannot ignite the explosive environment. Energy of the spark depends on parameters of the electric circuit (current, tension, the soprotivleyoniya, tanks, inductance). In order that energy of the spark did not exceed energy of ignition, select parameters of the electric circuit for the corresponding tables. The largest dopustiyomy capacities of chains at application of the intrinsically safe elektroyooborudovaniye are 2-60 W. These are chains of the alarm system, communication, distance control.
Legends of the explosion-proof equipment of the ustayonovlena Rules of production of the explosion-proof elektroyooborudovaniye: in the beginning put the letter meaning execution type, then the digit meaning category of explosive mix, and, nayokonets, the letter meaning groups of explosive mix. Napriyomer, I2A — the equipment in intrinsically safe execution for Wednesday in which explosive mixes of category 2, groups A are possible.
For explosive rooms of the classes B-I and B-II almost all electric equipment and lamps, including figurative, vybiyoratsya in blast-tight execution, in some sluyochayakh - intrinsically safe or special, for other classes - explosion-proof, corresponding to group and category of vzryvoyoopasny mix.
Irrespective of execution type removable parts of the elektrooborudoyovaniye seal up. The covers and other parts protecting tokoyovedushchy parts open the special key or supply with blocking.
Isolation of current carrying parts is chosen with the raised stoyyokost against dampness and chemical influences. The rotating parts able to cause sparking at accidental graze for other parts, produce from non-ferrous metal or protect the blast-tight cover.
Electric equipment, switches which are normally sparking under the terms works delete from places of accumulation of combustible materials or take out out of borders of the room. Power electric equipment, devices, devices and conductings protect from mechanical and chemical influences and also from dampness. Connection and dividing boxes choose in the dustproof ispolyoneniye. The electrical wiring are carried out by the protected wire like VRG or SRG in pipes. Contact connections cook or molded.Top