4
2. Mechanical Installation
2.1
General Installation Guidelines for Tank Mounts
1.
The mounting surface for base and top plate must be level. After installation, the top
and bottom plates must be level within
±
0.5
°
. If the mounting surfaces are not level,
then shims and or grout may be used to level the mount.
If possible, check that the mount is level when the vessel is fully loaded because
excessive deflections in legs and supporting structures may cause additional side
forces which greatly affect accuracy. Deflection of the mount’s top or base plate due
to loading should not exceed
±
0.5
°
. Reinforcement of legs or other support
structures may be necessary to correct this. Vessels with long legs should have cross
bracing applied between adjacent legs to keep them from spreading under load.
2.
Compression mounting systems use three, four, or more mounts. More than eight-
mount systems should be avoided as even weight distribution becomes extremely
difficult to achieve. The load on each mount assembly should vary by no more than
20%. Add shims where necessary to achieve correct load distribution.
3.
If the actual load cells are used during installation, take extreme care to prevent
overload damage. A tank or hopper can exert huge forces when dropped only a
fraction of an inch. Dummy load cells can be used during installation.
4.
It is crucial that all piping or conduit be horizon-
tal and flexible. If flexible piping is not used,
make sure distance from vessel to the first pipe
support is 20-30 times pipe diameter. For details,
see the “Technical Information” section of the
RLWS Load Cell Product Selection Guide. In
smaller, lower capacity tanks and hoppers, iso-
lating resultant forces becomes extremely criti-
cal.
5.
Load cells should not be installed in mounts until all welding is completed. The heat
generated from welding current passing through a load cell can damage the adhesive
holding the strain gauge to the body. If possible, use a dummy load cell when
welding to maintain finished height. If welding is unavoidable after load cell
installation, connect the ground in such a way that the current does not flow through
the load cell. For example, if welding on the mount top plate, the ground must be
connected to the vessel, not to the mount base or support structure. Also, protect the
load cell and cable from weld splatter.
6.
Use only “hermetically sealed” RL71000HE load cells in washdown applications.
“Environmentally protected” load cells are not suitable for such applications and
will be damaged. If tanks and surrounding equipment are frequently steam cleaned
or if the load cell is subjected to direct washdown, a protective shroud for the
weighing assembly is recommended. Proper drainage is necessary so the weighing
assembly is not standing in water.
7.
All support points should be equally stiff so that they deflect by the same amount
as the vessel is loaded.
LEVEL
±
0.5
°
FLEXIBLE PIPING
J-BOX
