How do I determine the accuracy of my Hardy floor scale?

There is a simple and a complex answer to this question of floor scale accuracy. The answer is different for floor scales than using load cells under vessels, hoppers, etc. Please review additional web tech answers for load cell accuracy. Check out the link for the answers other found helpful below.

The other helpful file linked below speaks of how different applications affect your weighing accuracy.  With floor scale's the load sensor capacity is twice the rated load.   Which indicates you would have a more accurate weighing system if you used individual load cells and loaded from the top.  An application specifications state the expected accuracy and how a system is loaded as part of that application requirement.  If accuracy is of the utmost, consider modifying the application to use an individual load point scale system with top loading and discharging characteristics.  A floor scale is a simple device that provides a mobile and easy to setup scale system.

The simple answer is a rule of thumb that states the accuracy of your floor scale is 0.03% of the rated scale capacity posted on the scale.  Not the total of the load cell capacity.  A floor scale has a load cell capacity total of twice the rated capacity.  This is to insure you do not overload the scale by placing the rated load over one set of load cells.

The complex answer comes from Handbook 44 that you can download at:

http://www.nist.gov/manuscript-publication-search.cfm?pub_id=906701

If you review section 2.20 you can better understand the complexities of determining floor scale accuracy.

Before designing a system, an engineer should consider carefully the expected accuracy and then relate this to the component capacities making up the system. No physical measuring system can be completely accurate. An error band must be defined for a system which gives an indication of expected deviations from true value. The parameters under which this applies must also be clear and concise. Floor scale accuracy terms such as "1 part in 3000" are commonly used.