Abstract: A redundant level measuring system comprises a chamber for fluidic coupling to a process vessel whereby material level in the vessel equalizes with material level in the chamber. A float including a magnet in the chamber rises and falls with material level in the chamber. A magnet actuated visual indicator is mounted to the chamber for indicating level of the magnet in the chamber. A measurement instrument includes an antenna and a measurement circuit. The instrument is mounted atop the chamber with the antenna extending downwardly into the chamber. The measurement circuit measures time of flight of a through air signal representing level of the material in the chamber. A shield in the chamber isolates the float from the antenna.

Abstract: A redundant level measuring system comprises a chamber for fluidic coupling to a process vessel whereby material level in the vessel equalizes with material level in the chamber. A float including a magnet in the chamber rises and falls with material level in the chamber. A magnet actuated visual indicator is mounted to the chamber for indicating level of the magnet in the chamber. A measurement instrument includes an antenna and a measurement circuit. The instrument is mounted atop the chamber with the antenna extending downwardly into the chamber. The measurement circuit measures time of flight of a through air signal representing level of the material in the chamber. A shield in the chamber isolates the float from the antenna.

Abstract: A redundant level measuring system comprises a chamber for fluidic coupling to a process vessel whereby material level in the vessel equalizes with material level in the chamber. A float including a magnet in the chamber rises and falls with material level in the chamber. A magnet actuated visual indicator is mounted to the chamber for indicating level of the magnet in the chamber. A measurement instrument includes a probe and a measurement circuit. The instrument is mounted atop the chamber with the probe extending downwardly into the chamber. The measurement circuit measures a characteristic of the probe representing level of the material in the chamber. A shield in the chamber isolate the float from the probe.

Abstract: A redundant level measuring system comprises a chamber for fluidic coupling to a process vessel whereby material level in the vessel equalizes with material level in the chamber. A float including a magnet in the chamber rises and falls with material level in the chamber. A magnet actuated visual indicator is mounted to the chamber for indicating level of the magnet in the chamber. A measurement instrument includes a probe and a measurement circuit. The instrument is mounted atop the chamber with the probe extending downwardly into the chamber. The measurement circuit measures a characteristic of the probe representing level of the material in the chamber. A shield in the chamber isolate the float from the probe.

Abstract: A dual compartment housing has a wiring compartment containing customer accessible wiring board and openings for a conduit connection. The wiring compartment is separated from an electronics compartment by a tunnel. The tunnel, which can be potted with a sealing compound, provides environmental and explosion proof protection for the electronics. An intrinsically safe barrier can be housed in the explosion proof wiring compartment, and the electronics compartment is then intrinsically safe. This relieves any constraint on separating the intrinsically safe electronics exposed to the process by an explosion proof boundary, and the process seal can be a "soft" seal. The housing is designed so that both compartments face the same direction.

Abstract: An improved housing assembly is used for a microwave level sensing instrument for sensing level of a process fluid in a vessel. The process vessel includes a vessel flange defining an opening into a storage space in the vessel. The housing assembly includes a flange assembly including a housing flange having a distal gasket face sealingly mateable with the vessel flange in use. The housing flange is connected to a window housing for housing a window spaced from the gasket face and providing a process seal. An electronics housing is mounted to the window housing. The electronics housing supports a microwave antenna proximate the window for focusing energy through the window to the process fluid.

Abstract: An improved mounting arrangement is shown for a magnetostrictive level sensing instrument for sensing level of a process fluid in a process vessel. The process vessel includes an opening into a storage space in the vessel. The improvement includes an elongate tube having a closed end and an opposite open end. A process fitting receives the open end of the outer tube, the process fitting being adapted to be received in the vessel opening, in use, whereby the process fitting and the elongate tube seal the vessel opening. A magnetostrictive wire assembly is removably received in the elongate tube through the open end for operatively sensing position of a magnetic float captured on the elongate tube and floating atop the fluid in the vessel. A housing is mounted to the adaptor fitting and supports the wire assembly when the wire assembly is received in the tube.