Dear Mr. Rajendrakannan,

I will suggest the following options:

Typically, if there is liquid specified in the vessel, the static head of that liquid should be considered when designing nozzles. So, if you do not specify any liquid, the static head will be 0 and all nozzles will be designed per design pressure.

Other option would be put the nozzle at the top of the vessel, in that case even if you specified the liquid, static head acting on the nozzles at the top will be zero.

You could also analyze this nozzle separately in the Component Analysis Module of PVElite (CodeCalc). There you can specify the pressure yourself.

Hope it helps.