What is Explosion?
The precondition causing explosion is that explosive material must mix with oxygen in some proportion and cause a chemical reaction under proper ignition conditions. It will be defined Explosion if reaction speed exceed sound velocity.
When explosive mixture run up to a certain extent. it will explode suddenly and cause destructive effects in the form of explosive wave.
What is Anti-Explosion?
Explosion can be prevented if anyone condition of three conditions above-mentioned is restricted to happen. In many working sites, explosive material and oxygen are difficult to avoid, so the ignition source should be restricted.
The electric equipment is a potential ignition source, this result in a elevatory surface temperature, ESD or a electric spark caused by transient current, etc. when the machine is turning.
The anti-explosion electric equipment doesn’t become potential ignition source. because it avoids elevatory surface temperature and electric spark caused by the current in the process in the design.
Classification by potential explosive environment
Electric equipment used in explosive gas atmosphere is usually divided into two categories:
I. electric equipment designed for colliery;
II. electric equipment designed for other explosive gas atmospheres except for colliery.
For electric equipment II, it can be divided into three magnitudes of explosion of II A, II B, II C according to MESG (Exd) and minimum experimental ignition current (intrinsic safety type) of detonating gas. and the equipment II B is suitable for service conditions of equipment II A, the equipment II C is suitable for service conditions of equipment II A and II B
For electric equipment ll, it can be divided into six temperature groups of T1 (450°C) , T2 (300°C) , T3 (200°C) , T4 (135°C) , T5 (100°C) , T6 (85°C) according to allowable maximum surface temperature, and the equipment of higher temperature group is suitable for service conditions of lower temperature group.
More than 90% explosive gas are included in magnitudes of explosion of II A, II B and temperature groups of T1-T4.
Magnitude of explosive
How to perform Anti-explosion?
There are different ways to make electric equipment suitable for an explosive environment, there are detailed descriptions of these ways in standards GB3836, IEC60079, EN50014, etc.
DCL anti-explosion series electric actuator is manufactured as a type of Exd and matches up to requirements of standards-GB3836.1-2010, GB3836.2-2010.
Exd actuator allows interior explosion, the flameproof joint of the casing is designed to prevent the contact of interior sparks or explosive carrier with the outside. Appropriate flameproof joint gap and adequate flameproof joint width can assure this. At the same time, a hard casing can withstand high pressure caused by interior explosion without being damaged.
The following components of DCL anti-explosion series actuator are designed and manufactured by the standard of Exd.
u Electric Motor Cavity
u Electronic Component Cavity
u Connection Cavity
The anti-explosion grade of DCL anti-explosion series electric actuator is: Exd II BT4Gb
D—anti-explosion type stands for explosion-proof type;
II—equipment type stands for the electric equipment designed for other explosive gas atmosphere except for colliery; B-magnitude of explosion, it determines the size (width and gap) of each flameproof joint of the actuator;
T 4—temperature group stands for the highest surface temperature allowed of actuator is 135°C.
Gb—Standards for protection grade.
How to use and maintain the equipment of Anti-Explosion?
Operation such as installation, adjustment, maintenance, repair and replacement must be performed by trained and qualified explosion-proof professional technicians and must be strictly performed according to [Operation Manual] of electric equipment.
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