Encapsulation

Name of the Safety Technique: Encapsulation

Symbol : m

Guidelines : IEC 60079-18

Type of protection whereby parts that are capable of igniting an explosive atmosphere by either:-

1. Sparking
2. Heating

Are fully enclosed in a compound or other non-metallic enclosure with adhesion (Adhesion : moisture, gas and dust tight permanent bonding of a compound to a surface) in such a way as to avoid ignition of a dust layer or explosive atmosphere under operating or installation conditions.

The most important parameter of the compound is the Temperature Range within which the properties of the compound, during storage or operation, remain in compliance with the requirements of IEC 60079-18

The compounds (used for encapsulation) are expected to retain their protective properties all throughout the , storage ,working life and operating temperature .

The compounds to be used in this type of protection technique are required to have special properties and are thoroughly tested for Temperature Endurance ,Water Absorption and Dielectric Strength , along other parameters.

The specifications of the compound are outlined in IEC 60079-18

Protection provided by ENCAPSULATION has following three levels :-

Equipment Protection Level=Ma , Ga, Da (alternate marking =  ma)

(Important requirement for ma : The working voltage at any point in the circuit shall not exceed 1 kV )

 EPL=Mb , Gb, Db  (alternate marking =mb)

 EPL=Gc , Dc  (alternate marking =mc)            (This level of EPL is not used in MINES )

Equipment having a higher EPL can be installed in less hazardous areas but the solution may not be economical .

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