# Calculation Methods - Expansion Joint/Stuffing Box

For pipe expansion joints the calculation of pressure loss is explained below: 1. For Lyre Bends, a pressure loss coefficient, K is determined by pipe outside diameter, according to the formula: K = 1.6 + 2 Doutside The calculated K value is then used in the expression K = 2 ΔP / (ρv2) 2. For II shaped expansion bends the pressure loss coefficient is calculated according to the formula: K = 1.9 + 2 Doutside The calculated K value is then used in the expression K = 2 ΔP / (ρv2) 3. For stuffing boxes FluidFlow uses a K value of 0.2. Idelchik [5]