Baker Hughes Masoneilan 12400 Series Instruction Manual & Safety Manual Download

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Masoneilan 12400 Series Transmitter/Controller Instruction Manual | 15

5. Case description

The purpose of this section is to describe the various instrument sub-assemblies to facilitate their use and maintenance.

See figures 8 to 13.

5.1. ELECTRONIC COMPARTMENT

The electronics compartment, located at the front of the instrument, can be accessed by removing the main cover (281). This

main cover is equipped with a glass (251) and three explosion proof pushbuttons (260).
The cover (281) is fully screwed on to the case (2) and sealed with an O-ring (109). It may be necessary to unscrew the cover by

less than a turn to align the window and LCD display and to install the safety screw (110). The cover (255) protects the

pushbuttons.

The sensor S/A (40) and its seal (111) are secured by two screws (112), located in the upper part of the electronics compartment.

The microprocessor, the display and the three pushbuttons are mounted on the resin potted electronic board which makes the

main electronic module (200). This subassembly is inserted into the case with the display facing the top of the case. It is

assembled by four screws (201).

5.2. MECHANISM COMPARTMENT

The mechanism compartment (Figures 12 & 13) on the back of the case has an opening on the right side (operator facing

instrument), which is closed by a threaded cover (107) and a gasket (108). A second opening at the bottom, closed by a special

3/4” NPT plug (190),

allows access to the mechanical flexure (59), which is part of the beam.

The mechanism (50) is completely factory assembled and calibrated before being installed into the mechanism compartment.

The pivot (51) is positioned toward the back of the case through two pins (52-53) and fastened by two screws (113).
Two set screws (114) are located in tapped holes in the side of the case. The holes are covered by two plugs (115).

5.3. MTBF

The MTBF (Mean Time Between Failure) of 12400 Series instrument is 55.7 years, according to MIL-STD-HDBK-217F

Specification.

5.4. CONNECTION COMPARTMENT

Located on the left side, the connection compartment is closed by a threaded cover (104) with O-ring gasket (105) and locked

by a safety screw (106). It is equipped with a terminal board (90) mounted with a screw (92).
To mount the safety screw (106), the cover must be fully screwed on the case and then unscrewed by less than a turn.

5.4.1. E

LECTRIC CIRCUIT

Both the terminal strip and the ground terminal are located in connection compartment (Figures 8 and 9). Connections are done
with four flat handle terminal blocks (90) or a terminal board connector (90A) (Japan) and included ground connection (96). Follow
strip rules to prevent from any short circuit and comply with local and national standards for hazardous area installations.

A 1/2” NPT (or M20) conduit connection is p

rovided in the lower part of the junction box for connecting the supply leads via a

supplied stuffing box with an integrated cable clamp device or any cable gland with cable clamp device suitable for the
considered hazardous area.

DANGER:

FOR ANY ACTION ON 12400 SERIES INSTRUMENT, DO NOT REMOVE EITHER COVER PRIOR TO READING
GEA19100 (400152322) ATEX INSTRUCTION MANUAL.