The flushing ring and remote seals are there to prevent loss or degradation of the signal, ether through a leak or condensation.

There is no debate. The manufacturer will spell out quite clearly where and when they are to be used. If you follow the manufacturer specs., you wont have any problems.

Dear

in the connection between the remote seal flange and the piping flange, the flushing ring is used to clean and drain the remote seals when it is required.

Normally the remote seals is used when you dont want to transfer the process fluid into the measurment instrument. or when you want to install the measurment instruemnt far from the process connection/the process fluid.