Im and current looking at the installation of 3 pressure transmitters on a steam condenser. Currently they are installed using a ring type siphon tube (like a gauge pressure situation on a vertical pipe). 2 of the transmitter are reading the same, and one is reading 100mbar more negative. If I introduce a leak to the 2 high pressure transmitters enabling the condensate leg to be sucked into the condenser, the pressure equals the 3rd transmitter but slowly increase when sealed (condensate build up). The 3rd transmitter seems to be reading correctly by looking the the temperature environment in the condenser. Due to the vacuum which causes lack of stability in the condensate head, is the best practice to use an oil filled transmitted (protect against possible high temps) and mount it above the tapping point so the condensate drains?

Thanks in advance

 

100 milbars ~ 1 meter of water, do you have a condition where condensate is forming between the syphon and transmitter creating a negative offset?

If so raise the syphon to the same elevation as transmitter diaphragm.