Evaporator in a Compressed Liquified Gas Line

I've an evaporator in a compressed liquefied gas line... i know that evaporator building up pressure, my question is which area should be most critical up stream the line where the evaporator is,or back the line to the CLG stored?

and if it is down stram how i'll ensure i'dont have vapor downstream?

Some basic data required:

Is it LPG?

What is the flow rate?

What is the pressure in the (1) storage vessel (2) pipe line, downstream of the vapouriser?

Do you require liquid or vapour at the usage point?

What is the appliance?

thanks for your time

Is it LPG? it is chlorine gas not LPG

What is the flow rate? flow rate at application point is around 3000 lbs/day

What is the pressure in the (1) storage vessel (2) pipe line, downstream of the vapouriser? 1-around 100 PSI (2) almost the same

Do you require liquid or vapour at the usage point? Vapour is required

What is the appliance? water disinfiction