Rice Lake Z6 Single-Ended Beam, SS Welded-seal, IP67, OIML C3 - Manual (Page 5)

Load Cell Types 1
1.0 Load Cell Types
Load cells are built in various sizes and types for various
applications. We will look at the different type of load cells.
1.1 Canister
The canister cell is the earliest load cell design. It is either
hermetically sealed or welded to protect the gauges.
See Figure 1-1 Canister Load Cell.
Canister cell popularity is waning as their cost is 2 or 3 times
that of a bending beam cell. There are two types of canister
c o n s t r u c t i o n , s i n g l e c o l u m n a n d m u l t i p l e c o l u m n .
Single-column canisters cannot normally withstand a side
load of over 15%. Multiple column canister cells withstand
more side load than the single-column variety. The canister
cell ranges in size from 100lbs up to 500,000lbs. The normal
safe overload is 150% of full scale (F.S.) but some models are
able to withstand a 300% F.S. overload. There is no means
through visual inspection or labeling to identify which cells are
singular or multiple column. Refer to original manufacturer’s
specifications or Rice Lake Weighing Systems’ Load Cell
Guide to determine your cell’s specifications.
Canister cells are made of high alloy tool steel with an epoxy
finish, or stainless steel. Their rated excitation ranges from
10VDC to 20VAC/DC. Common bridge resistances are 350Ω
and 480Ω.
Figure 1-1. Canister Load Cell
1.2 Single-Ended Beam
The single-ended shear beam cell is designed for low-profile
scale and process applications. The shear-beam cell strain
gauge cavity contains a thin metal diaphragm onto which the
strain gauges are mounted. Typical shear beam capacities
range from 1,000lbs through 20,000lbs, although some
manufacturers offer shear beams up to 40,000lbs. One end of
the shear-beam contains the mounting holes while the
opposite end is where the cell is loaded. The cell should be
mounted on a flat, smooth surface with high strength
hardened bolts. The larger shear beam cells have more than
two mounting holes to accommodate extra bolts and keep
the hardware from stretching under stress load. See
Figure 1-2 Single-Ended Shear Beam.
Shear beams operate best in a temperature range of +15°F to
115°F. Their maximum safe operating range with minimum
performance change is from 0°F to 150°F. Shear-beam zero
outputs should be frequently checked when operating at high
temperatures. These cells may be overloaded statically up to
150% of rated load without damage. Overloads in excess of
the safe overload rating may permanently affect the accuracy
and performance of the cell. Shock loads having peak values
in excess of 120% of rated cell capacity may also affect the
calibration and should be avoided.
Shear beams may be constructed of tool steel, or stainless steel
for use in harsh environments. Just because a cell is made of
stainless steel does not mean it can be used in washdown
environments. Appropriate sealing is also important.
Figure 1-2. Single-Ended Shear Beam
1.3 Double-Ended Beam
The double ended shear beam characteristics are similar to
those of the single-ended shear beam. The most common
bridge resistance for this load cell is 700Ω. It is most
commonly used in truck scales and tank and hopper
applications. Instead of being secured at one end with the
load applied to the other end as in the single-ended shear
beam, the double-ended shear beam is secured at both ends
with the load applied to the center of the load cell. As in all
shear beam designs the strain gauges are mounted on a thin
web in the center of the cell’s machined cavity. See Figure 1-3
Double Ended Shear Beam.
1.4 Cantilever Beam
Cantilever beams are similar to shear beams. However, the
cantilever beam does not have a thin web located in the strain
gauge cavity. The cantilever beam is machined all the way
through. The strain gauges are mounted along the inner
edges of the cavity. Most cantilever beams have a bridge
resistance of 350Ω and either 3mV/V or 2mV/V full scale
outputs. They range from capacities of 25lb up to 10,000lbs.
However, there may be a few larger cantilever beams being
u s e d . T h e y c a n b e u s e d i n t e n s i o n o r c o m p re s s i o n
applications.
Can
Heliarc Weld
Column
Axial Strain
Gauge
Transverse Strain
Gauge Electical
Compensation
Components
Diaphrams
Load Receiving
Element
Shear Strain Gages
Stable Foundation
Mounting Bolts Load