Venting Backwards through a Steam Jet

[Chance17]

I am evaluating a small styrene/water seperator drum mounted at grade. The vessel MAWP=30-psig.
External Fire is the only significant contingency.
The drum has no individual safety valve. There is a small 3/4" vapor balance line.

There is an alignment from the drum to a nearby safety valve with 28-psig set pressure.
The alignment is backwards through a steam jet.
The client argues the steam jet represents minimal restriction. I really wonder ??

Question: Is the relief path "from drum - backwards through jet -- to safety valve" endorseable as good engineering practice ??
Any comments are appreciated.

 

[zdas04]

As long as you can get adequate flow through the nozzle (it most likely will not be choked flow) and the pipe is big enough and there are no intervening check valves, block valves, or control valves then having multiple vessels protected by a single PSV is reasonable.

You need to do the flow calcs in the 3/4 inch line and the nozzle. Then you need to get your required flow right (in the calcs for the fire case, one of the inputs is the wetted area, you have to add the wetted area of both vessels together to calculate the required PSV flow).

David