Parts of pressurized and non-pressurized RoR intake

Main parts of a non-pressurized RoR intake

1. Approach channel / river training with guide wall.
2. Intake sill (about 1.0-1.5 m above the undersluice or river bed) to stop bed load.
3. Trash rack (inclined at 70-80°) with a trash boom in front.
4. Gate (regulating gate) with a stop-log slot and hoist deck.
5. Transition / bell-mouth to the gravel trap and the approach canal / settling basin.
6. Flushing (undersluice) gate and flood wall.

NON-PRESSURIZED INTAKE (section)
 pond ~~~~~~~~~~~~~~~~~~~~~~~
      boom  | hoist deck
   --o--    |  |gate
 trash  |##\ |  |
 rack   |##  \|  |_______ free flow --> canal
 sill   |_______|
 ///////////////////////////// river bed

Main parts of a pressurized intake

1. Approach and trash rack (inclined or vertical, large area, with rake).
2. Bell-mouthed entrance (to reduce entry loss).
3. Minimum submergence below the lowest operating level, with an anti-vortex device.
4. Emergency gate and service gate in a gate shaft, with an air vent behind the gate.
5. Transition from rectangular to the circular pressure tunnel/penstock.

PRESSURIZED INTAKE (section)
 min WL ~~~~~~~~~~~~~~~~~~~~~~~~
        |  air vent
 rack   |##  |gate|
 S      |##  |    |
 _______|bell-|____> pressure tunnel (full)
        mouth

Proportions: rack velocity 0.8-1.0 m/s; the bell-mouth length is about 1.5-2 times the conduit height; the submergence is chosen by the vortex criterion $S\ge C\,V\sqrt D$.