It is a commonly asked question: Is it better to use three or four load points on a scale? In theory, you can use any number of load points (load cells) to support a vessel. The actual number used is dependent upon these factors:
- The vessel’s geometry (shape and number of supports).
- The vessel’s gross weight (both live and dead weight).
- The vessel’s structural strength.
- The environment in which the vessel is located.
- What is available structurally to provide a stable, load-bearing support.
- The characteristics of the material being weighed.
Three Load Points
For short, upright cylindrical vessels in a compression installation, three load points spaced at 120° intervals provide the most convenient support. Three-leg weighing systems balance like a tripod, with load distribution being virtually automatic, and they only require minor balancing at installation. You must install all of the load cells in the same plane within 3° of each other.
Cylindrical vessels suspended symmetrically in tension with three load points provide the advantage of equally distributing the load among the load cells. What is available structurally is important in this situation.
A vessel in tension can be hung in a corner where there are two supporting structures at right angles. All it requires is a 45° cross brace to provide support for the third load point. Of course, the support beams must be sufficiently strong and stiff to support not only the fully loaded vessel, but also other vessels that may be supported from the same structure, and any changes in the structural load, such as an accumulation of snow, water or ice.