sealed fitting question

[gareth0127]

It appears to me that a sealed fitting is required on explosionproof equipment to prevent the explosion leaving the equipment through conduits, cables etc. Ive also read that these sealed fittings cannot be relied on to prevent gas entering the explosionproof fitting.

It also seems that sealed fittings are used at the boundary between to different area classifications to prevent the transfer of gas between these 2 different areas.

Am I reading into this correctly as the two points contradict each other? Either a sealed fitting can prevent the transfer of gas or not.....can somebody clarify this for me?

Thanks

 

[rbalex]

See Section 501.15 FPNs. Boundary seals are to minimize, not eliminate the passage of gases.

 

[gareth0127]

thank you, its all in the details!