Remote seal process pressure measuring system

摘要

A process pressure measuring system includes a transmitter having a first sealed system in which a first outlet couples to a pressure sensor, a first isolator diaphragm assembly, a first capillary passage, and a first isolation fluid. The first isolation fluid couples a first pressure from the first isolator diaphragm to the first outlet and the pressure sensor. A second sealed system includes a second pressure outlet that is coupled to the first isolator diaphragm assembly, a second isolator diaphragm assembly, a second capillary passage and a second isolation fluid. The second isolation fluid is adapted for use in a first temperature range and couples a pressure from the second isolator diaphragm assembly to the second pressure outlet. A third sealed system includes a third pressure outlet that is coupled to the second isolator diaphragm assembly, a third isolator diaphragm assembly, a third capillary passage and a third isolation fluid. The third isolator fluid is adapted for use in a second temperature range and couples a process pressure to the third pressure outlet.

主权项

1. A process pressure measuring system, comprising:
a first sealed system that includes a first pressure outlet, a pressure sensor, a first isolator diaphragm assembly and a first capillary passage filled with a first isolation fluid that couples a process pressure from the first isolator diaphragm assembly through the first capillary passage and the first pressure outlet to the pressure sensor; a second sealed system removably mounted to the first sealed system and that includes a second open pressure outlet, a second isolator diaphragm assembly and a second capillary passage filled with a second isolation fluid for use in a first temperature range, the second isolation fluid coupling the process pressure from the second isolator diaphragm assembly through the second capillary passage and the second open pressure outlet to the first isolator diaphragm assembly and including a first fill tube coupled to the second capillary passage, the first fill tube used to fill the second capillary passage with the second isolation fluid; a third sealed system removably mounted to the second sealed system and that includes a third pressure outlet, a third isolator diaphragm assembly, couplable to a source of the process pressure in a second temperature range, different than the first temperature range, and a third capillary passage filled with a second isolation fluid, different than the first isolation fluid, that couples the process pressure from the third isolator diaphragm assembly through the third capillary passage and the third pressure outlet to the second isolator diaphragm assembly and including a second fill tube coupled to the third capillary passage, the second fill tube used to fill the third capillary passage with the third isolation fluid; and the process pressure coupling through the third, second and first sealed systems to the sensor, and the use of isolation fluids with different temperature ranges reducing inaccuracies in a sensed pressure at the pressure sensor.