ADS Environmental Services FlowAlert QR 775011 A2 - Manual (Page 42)

Pressure Depth Sensor and Float Switch Installation 3-19
3. Place the ring in the input pipe at least 12 inches upstream from
the manhole or edge of the pipe with the sensors facing
upstream toward the oncoming flow. It should be located far
enough upstream from the manhole to minimize the effect of
the draw-down caused by a possible drop in the manhole invert.
Installing the ring at least 12 inches upstream from the manhole invert
Keep the following in mind:
 Make sure the spreader mechanism is at the top (crown) of
the pipe and the pressure depth sensor is at or near the
bottom of the pipe, above any silt present and below the
flow surface (during minimum flows).
Proper orientation of the ring with the sensors in the pipe with and without
silt present