ADS Environmental Services Model 4000 530017 A0 - Manual (Page 42)

Monitor and Sensor Installation 3-19
If necessary, temporarily clear away silt to install the ring.
Make sure the ring is flat (flush) against the inside wall of
the pipe to avoid obstructing the flow or catching debris.
4. Expand the ring by turning the spreader mechanism nut
counter-clockwise with the crank handle or socket. However,
do not tighten the ring against the pipe completely at this
point.
5. Level the ultrasonic depth sensor at the top of the pipe so that
the sensor face is parallel and level (from side to side) with the
flow surface and pipe crown.
Leveling the ultrasonic depth sensor
If necessary, adjust the level in the following way:
Remove the ultrasonic depth sensor from the mount.
Loosen the ring slightly to allow the plate to move on the
ring.