What is Molecular seal in flare system?

[kjt8710]

I am working about FPSO detail engineering now.
I would like to get information about molecular seal and velocity seal for flare system.

Please advise it.

 

[DuhonGATE]

"molecular seal" is an unfortunate name given to a flow restriction installed in a flare stack to minimize the amount of purge gas required. Purge flow is required to prevent air ingress into the flare stack. The flare vendor will have to provide details on design options and required purge flow.

 

[MortenA]

As far as i understand its a fancy name for a venturi in a vent - it needs a purge stream to be effective - but the purge stream can be lower with a molecular seal

 

[swm2]

check out api rp521 for further info