ARB RD197 - Manual (Page 26)

3 Installing the Air Locker
24
 While holding the seal housing tube into the bulkhead fitting, insert
the small drilled end of the center compression nut over the
extended tube as shown in the assembly diagram (Fig.19.), and
screw it into the bulkhead body, and lightly tighten.
Figure 19.
NOTE : Excessive tightening of the center compression nut is
not necessary to form a good seal around the tube
and may damage the O-ring, the seal housing tube, or
the threads of the compression nut.
NOTE : Make sure the seal housing tube is all of the way into
the center compression nut while you are tightening
it.