The ABB HART 266 Digital Diaphragm Seal (DDS) pressure transmitters have been designed to address issues that conventional remote seal system already address, plus many of the problems that traditionally require high costs or performance compromises.

This is especially valid when devices are to be installed on tall vessels or distillation towers. DDS are based on the reliable ABB sensing technologies and deliver a differential pressure (DP) measure through a digital approach to its calculation.

DDS is indeed a system, designed as the combination of two direct mount gauge sensors connected with a nonproprietary electrical wire.

The sensor to be installed on the high side of the DP measure, is defined as “Primary device” and embeds all the functions necessary to calculate the DP. It’s the “brain” of the system which transmits signals back to the DCS/control room leveraging a standard two-wires 4–20 mA HART signal.

The other sensor, defined as “Secondary” has the function to collect independently the pressure on the low side and transmits it to the Primary for elaboration. Such digital architecture has multiple advantages if compared against a traditional oil-based capillary system.