A-14
Appendix A Model 224 Differential Pressure Unit
Table A.2—Bolt Torque Ratings
HOUSING BOLT
LUBE
(Note 1)
TORQUE
LB-FT
(Note 2)
ROTATION
(Degrees)
(Note 3)
SWP MATL. MATL. SIZE
500 SST SST 1/4-28 x 2.5 YES 12-14 180
500 CuNi Monel 1/4-28 x 2.5 YES 9-11 180
1,000 Cu-Ni Monel 1/4-28 x 2.5 YES 9-11 180
1,500 SST SST 1/4-28 x 2.5 YES 12-14 180
3,000 SST SST 3/8-24 x 2.5 YES 35 90
6,000 SST SST 3/8-24 x 2.5 YES 40 135
Notes: (1) Lubricant: Molykote G paste, graphite-base grease, or similar lubricants. Lube fi rst
thread only. (2) Torque on bolts is accomplished in 3 or 4 steps. Tighten uniformly. (3) Cameron
recommends using a torque wrench whenever installing housing bolts. Rotation of bolt
head is measured after bolt is "snug" (approx. 1/16 turn past head contact) with approximately 2
ft-lb torque. Do not exceed this rotation. To tighten bolts without torque wrench, use the following
values: 1/4 turn = 90º, 1/2 turn = 180º
Changing the DPU Range
To change the range of the DPU, replace the BUA with a unit of the desired
range.
Replacing the Bellows Unit Assembly (BUA)
WARNING: Review the warning under DPU Maintenance, page A-12,
before performing this procedure.
IMPORTANT: Do not loosen the drive arm hole plug located on the top of the BUA
center block when removing the mounting bracket. If the plug is loos-
ened, the fi ll fl uid in the bellows will be lost and the unit will be inoper-
able.
1. Disconnect the DPU piping, remove the process monitoring instrument
from service, and remove the mounting bracket from the DPU.
IMPORTANT: See the manual for the process monitoring instrument for particular
components that must be removed to gain access to the DPU mounting
fasteners.
2. Loosen the drive arm from the process monitoring instrument and
separate it from the torque tube shaft. Do not disconnect the instrument
linkage.
3. Perform a pressure check of the DPU as follows:
a. Back off all housing bolts 4 turns.
b. Attempt to move the housing in and out along the bolts
If the housing moves freely, no pressure is present. Servicing or
repair may continue.
If the housing does not move freely, the bellows may be pressurized.
To Next Page
Loading...