SOP-HYD-006
REV 1.9
DRAFT TUBE & TAILRACE
Energy Recovery & Hydraulic Backpressure Management
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THE HIDDEN ENERGY THEFT
The Draft Tube recovers 30-40% of the turbine's power by creating suction. Every centimeter of "Backpressure" in the tailrace is a direct subtraction from the Net Head ($H_{net}$).
SILT IN ELBOW
In horizontal units, the 90° elbow is a sediment trap. Flow velocity drops here, allowing sand and rocks to settle.
ACTION:
Enter via manhole (LOTO 01). Clear bottom sand bars. Turbulence here
destroys suction efficiency.
LINER INTEGRITY
Inspect the upper 1m of the liner (closest to runner) for pitting or sponge-texture cavitation.
REPAIR:
If pitting > 3mm, use Underwater Grade Concrete Repair Mortar or weld
overlay.
TAILRACE CHANNEL PATROL
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VEGETATION: Clear overgrown bushes from banks to reduce friction.
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ROCKFALLS: Check tunnel exit for fallen boulders blocking outflow.
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VIBRATION LIMIT: Structural vibration on DFT door must be < 2.5 mm/s RMS (ISO 10816).