FRP verticle tank relief vent sizing

[Nerm]

I have an FRP seal pot used for an enclosed flare. The vessel is pressure rated to 4psi. I have a 16" vent line feeding into the tank through a dip tube which is submerged 6" below the water line. Then a 16" vent line feeding the flare. I am trying to size a emergency relief vent based on a flash back from the flare. Not sure on how to go about quantifying the pressure front generated from the flashback. The vent stream contains c3's to c5's in very low concentrations.

Anyone know where to look for estimating flame front pressures?

I am going to do more searching but came across this site and thought I would picks some brains.

Thanks

 

[roker]

hello,

why the material of construction chosen is FRP?

Try literature for flame arrestors.

regards,
roker

 

[Nerm]

This seal pot comes off our caustic scrubber (scrubbing SO2 gas). The FRP is for corrosion resistance. I would love nothing better than to put in a detonation arrestor but the history with this service has shown that the detonation arrestors sulfate up and the management is dead set against using them.

Another option would be to use a Fike valve but that is cost prohibitive at this point as the previous engineer who I am taking this project over from already ordered an O2 analyzer ... 2 years ago! I'm stuck with O2 analyzer and nitrogen dump for maintaining O2 levels below 4%.

So the worst case senario is that the O2 analyzer fails and I get a flashback in the line. Need to protect the FRP tank from this pressure wave, just not sure how to quantify it.

Thanks for the reply.

 

[Latexman]

Nerm,

Hmmmm. Do you know if the piping to the FRP tank is long enough to cause the deflagration in the pipe to accelerate to a detonation? I know it only takes 30-40 feet of 2-4" pipe to do that. How long is the 16" pipe feeding the tank?

Good luck,
Latexman

 

[EGT01]

Nerm,

I have no experience with explosion vents but you mentioned Fike. Have you talked with them about explosion vents? You may want to check their website for info.

http://www.fike.com/explosion_venting_products.html

They have an on-line calculator that might be of use. I notice their calculator references NFPA 68 Guide for Venting of Deflagrations and VDI 3673 Pressure Release of Dust Explosions so you may want to look into those as well.