Sampling and Gauging System for IFR Tank

This is with reference to one Internal Floating Roof ( API 650) Diesel Tank in a Refinery which have been provided with a weld neck flanged Manual dip gauge nozzle( 8" Size) . This tank is also provided with nitrogen blanketing.

However , with this arrangement we are facing a problem that whenever we have to do gauging and sampling of the tank contents , we have to depressurise the tank. Frequent depressurising the tank leads to loss of nitrogen from the tank and also leads to safety and health issues for operation personnel.

Can somebody suggest a suitable arrangement for sampling and gauging of tank in pressurised condition . OR suggest some reputed vendor address and phone no. who can provide us suitable system for the same.