Ex-pert Electrical Technologies

Dynamic elaboration on the Art & Science of Hazardous Area Protection

4. Protection Techniques

Types of Protection (from Ignition) Techniques for Electrical Equipment

Ex protection symbols 1

Ex protection symbols 2

Only certified explosion-protected electrical equipment should be used in the hazardous areas.

In order to facilitate the process of selection of appropriate electrical equipments , once the area has been classified into zones, standardized & certified electrical equipment ,incorporating standardized protection techniques may be used.

Each technique is based upon engineering and safety principles . The philosophy is continuously being evolved and monitored. The protection techniques are globally recognized and specified.

Specifications for each protection technique is well documented and supervised by international specification/standards bodies, which include:

  • IEC
  • NEC
  • CSA

Hazardous Area Electrical Equipment manufacturers may incorporate one or a combination of following standard techniques, as per requirement of the manufactured product.

The most common techniques used globally are as follows:

Flameproof (d )

symbol_dEx d JB

Intrinsic Safety ( i)

IS_symbolIS isolator Intrinsically safe Isolator

Increased Safety ( e)

symbol_eIncreased Safety Panel Increased Safety Control Panel (Ex ed , to be exact)

Pressurized Encasement ( p)

symbol_pPressurised Panel
Oil Immersion ( o)

symbol_o
Encapsulation ( m)

symbol_q_q
Powder Filled ( q )

ex symbol powder filling
Protection for Zone 2

ex protection symbol n_

It is obvious that electrical equipments certified for ZONE1 can be used in ZONE2 & ZONE21 in ZONE22 but not vise versa

Interesting protection techniques for NON-ELECTRICAL Apparatus in Explosive Gas Atmosphere and Combustible Dust

Ignition Source Monitoring                                                          Ignition Source Monitoring :   Reference  EN 13463-6  & R.Stahl

Sensors are integrated in the equipment to detect hazardous conditions to come , and to take steps against them before potential ignition sources become effective.The measures can be initiated automatically by means of a direct connection between the sensors and the ignition protection system or manually by issuing a warning message intended for the operator of the equipment.

Application

Pumps

Belt Conveyors

Liquid Immersion       Liquid Immersion    k                 Reference : EN13463-8     &    R.Stahl

Ignition Sources are rendered inactive by immersion in a protective liquid or by constant moistening using a liquid film.

Application

Submerged pumps

Gears