DH Instruments GFS2102, Руководство по эксплуатации и обслуживанию, Страница: 52 / 206

GFS2102™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company Page 36
which slips over the Swage nuts on each stem of
the loop and should have little clearance between
the hex shoulders of the two quick connect stems
when they are connected.
If you connect the loop to check this distance, be
sure to consider that gas will begin to flow from a
pressurized cylinder if the cylinder side of the
quick-connect is connected first. It is possible to
check this distance without connecting the loop by
resting the loop in the alignment tool upside down
and making sure the outlside surface of the hex
shoulders on each quick connect stem fit between
the quick connect bodies with little clearance.
Measure the distance between the ceiling of the
draft enclosure and the quick connect fitting on
the reference gas cylinder assembly. This
distance should match the distance from the
bulkhead quick connect fitting on the draft
enclosure sidewall column to the ceiling. If it is
not the same, adjust the height of the quick
connect on the sidewall column so that the flow
conveyance loop will sit level.
Measure the distance from the back wall of the
enclosure to both quick connectors. Reposition
the balance if necessary to ensure that the flow
path will be parallel to the back wall.
B. Quick check using loop
alignment tool.
C. Checking loop connector height.
Figure 22.
Checking height and
level of gas conveyance loop
connections
using loop alignment tool
3.3.12 AMH POSITION FINE ADJUSTMENT
Proper position of the AMH-GFS2102 assembly relative to the GFS balance is critical to
making accurate mass and flow measurements under flowing conditions. When the
reference gas cylinder is placed on the balance mass tray, the legs of the cylinder support
must pass through the AMH plates without contacting the plates, so that the cylinder mass
can be measured with the required sensitivity. This step must be performed AFTER section
3.3.11. Until the operator is fully accustomed to the setup, the steps in this section may have
to be repeated several times for proper alignment.
During setup, it is necessary to have access to “live” balance output and control of the
AMH platform movement, so communication should first be established between a PC
running GFS Tools software, the LCM which controls the drivers for the AMH-GFS2102,
and the GFS balance. See section 4.2.1. Continue setup with the AMH state set to have
the cylinder lowered.
After the proper balance location has been established (see Section 3.3.11), install the
AMH top plate onto the AMH base. The AMH top plate has a bubble level on the top
surface, but no reference mass hanging from it. The top plate should be oriented so that
the narrow holes for the reference gas cylinder support are aligned with the balance
mass tray; two holes on the left and one on the right. Lower the top plate over the two
steel posts on the front and rear of the AMH base. A tight tolerance is used for the fit of
the plates over the two posts so that the plates stay well-aligned while moving vertically.
Therefore, special care and some practice is required to slide the plates over the posts
without binding. Holding the plates at the area of the holes, ensuring that the plate is
held level and rocking slightly allows the plates to slide down into place. A light coating
of a clean lubricant like Krytox® can be used on the posts if needed. A small tube of
Krytox® is included with each new GFS system. When the top plate is fully in place, the
three rollers under the plate can be seen resting directly on the camshafts in the AMH
base.