Selection Criteria for Choosing the right packing

To avoid extrusion, the gap between shaft and housing, or between shaft and packing gland, should not exceed 2 % of the packing size for higher pressure valve applications and 5 % of packing size for lower pressure pump applications

Standard Construction:

d = Pump shaft / Valve stem size
D = Stuffing box bore
T = Stuffing box depth
Sp = Gap width
Rz = Surface roughness Shaft 1 to 5 µm
Housing 6-16 µm