# Calculation Methods - Abrupt Size Change

For all phase states, the pressure loss across an abrupt size change due to sudden enlargements is calculated from the expression: K1 = (1 - β2) 2 and for sudden contractions, the pressure loss across is calculated from the expression: K1 = 0.5 (1 - β2) where: β = the ratio of small to large pipe diameter. Note, subscripts 1 & 2 denote the internal diameter of the small and large pipes respectively. For a more detailed discussion and explanation refer to Crane [13].