Emerson Rosemount 228 Reference Manual page 24

Install
19.
20.
21.
18
For mechanical retraction assemblies, lock the retraction stop collar into position.
See Figure 2-8 or previously marked position for proper location.
Place the union nut O-ring at the bottom of the bushing housing. Insert the sensor
assembly into the retraction chamber and tighten the 3 in. hex union nut.
For mechanical retraction assemblies, install the nut housing cap.
See Figure 2-8 or previously marked position for proper location.
Reference Manual