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Section 4 Model 199 Differential Pressure Unit (DPU)
Section 4—Maintenance, Adjustment, & Calibration
Tools Required for Maintenance and Calibration
Cameron's calibration tool kit (Part No. 9A-0202-1005B) contains the tools
necessary for calibrating the Model 199 DPU. The tools listed in Table 4.1 are
also recommended for performing general maintenance.
Table 4.1—Tools
Description Purpose
7/16" Hex wrench Housing bolts
5/8" Hex wrench Housing bolts
1/8" Allen wrench Dampener Adjustment
1/2" Open ended wrench Push rod - bellows cup connection
Modied box/open-ended wrench (7/16") Kickoff spring lock nut
100 ft-lb Torque wrench Housing bolts
DPU Inspection and Cleaning
Instruments used in services where solids or semi-solids may accumulate
inside the pressure housings require periodic inspection and cleaning. Always
check for internal pressure using the procedure below before removing the
DPU housing bolts.
Pressure Check procedure
WARNING: Failure to perform this procedure can result in severe injury,
death or substantial property damage due to the release of internal
pressure. If the DPU has been installed in gas applications with working
pressures greater than 200 psig, PERFORM THIS PROCEDURE BEFORE
REMOVING THE DPU HOUSING BOLTS.
1. Back off all housing bolts 4 turns.
2. Check for internal pressure by attempting to move the housing in and out
along the bolts.
a. If the housing moves freely, no pressure is present and servicing or
repair may continue.
b. If the housing does not move freely, the bellows may be pressurized
and is potentially hazardous if further disassembled. Tighten the
bolts and return the unit to the factory or authorized Barton service
center for repair. Tag the unit and specify "Gas in Bellows".
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