Maximum safe load ($\mathrm{Lim}$)

The maximum safe load of a weighing scale, denoted $\mathrm{Lim}$, is the greatest static load it can carry without permanently changing its metrological qualities. This is the terminology of OIML R76-1:2006(E).^[ref] The definition concerns preservation of measurement behaviour, rather than merely whether the instrument remains visibly intact.

The maximum weighing capacity $\mathrm{Max}$ specifies a different property: the upper weighing capacity, excluding additive tare capacity. For an illustrative instrument marked $\mathrm{Max}=10\mathrm{kg}$ and $\mathrm{Lim}=15\mathrm{kg}$, a $12\mathrm{kg}$ static load is above the declared weighing capacity even though it is below the stated maximum safe load. The larger number does not extend the measurement range specified by $\mathrm{Max}$.^[ref]

A simple model shows why metrological integrity is a stronger requirement than absence of breakage. Suppose a load permanently changes a mass indication from $r(m)=m$ toThe mechanism may still carry loads and return to an indicated zero, but a reference mass of $5\mathrm{kg}$ now indicates $5.01\mathrm{kg}$. In this invented example, the response has changed by $0.2\%$ without a zero offset. A calibration at nonzero loads would reveal that change; resetting a zero-setting device would not remove it.

The static qualification also matters. A falling object can impose a transient force different from its supported gravitational weight. A rating expressed through a static load therefore does not, by itself, specify response to an impact or a crash pulse.