Material Unaccounted For (MUF)
Material Unaccounted For (MUF) refers to the difference between the book inventory of material and the physical inventory of material for an MBA over a material balance period. The following equation is used to calculate MUF:
MUF = (PB + X - Y) - PE
Where, PB is the beginning physical inventory, X is the sum of increases to inventory, Y is the sum of decreases from inventory, and PE is the ending physical inventory.
The book inventory is the algebraic sum of PB, X and Y, which implies that:
MUF = BI - PE
For item MBAs, MUF should be zero, and a non-zero MUF is an indication of a problem (e.g. accounting mistakes). For bulk handling MBAs, a non-zero MUF is expected for three main reasons: 1) the measurement uncertainty; 2) the nature of processing; and 3) operator's measurement uncertainties associated with PB, X, Y, and PE. These quantities are combined to determine the uncertainty of the material balance σMUF.
|MUF| < 3σMUF
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