How do I calculate the cross-sectional (c/s) size and the quantity of Compression Packing rings?

To calculate the required number of packing rings you will need the stuffing box depth divide by the packing C/S and round to the nearest whole number. You will also need to know the shaft diameter or sleeve diameter (I.D.), the box diameter (O.D.), and the stuffing box depth: (c/s) = (O.D - I.D.)/ 2.