Forces on Bends and Surge Control Flashcards
What is thrust?
A change in direction or shape of flow.
How is thrust mitigated?
- Concrete anchorages for bends
- Welded anchorages for forward movement and on slopes.
What is surge?
Caused when water flow stops abbruptly.
What are the main causes of surge in a pipeline?
- When a valve is closed to quickly.
- When a pump cuts out suddenly.
How can you mitigate surge times?
- By calulating the pipe period for valves and ensuring that the closing time does not exceed it.
- Ensuring the flywheel in a pump is sufficient to overcome surge due to cut outs.
- Ensure current fittings stay below the Jakowski head.
What is the minimum reccomended pipe period for general installations?
2.5 seconds
What is the calulation for thrust forces in a bend?
What is the calulation for thrust forces in a ‘T’ piece?
What is the calulation for thrust forces in a restriction?
How can you calulate the mass/ volume required in a thrust block?
If flow is stopped instantaneously, what is the calulation for change in pressure and change in head?
Where ‘c’ is the velocity of pressure wave propogation.
What is the equation to calulate surge when fluid is in a pipe that is in an anchorage?
What is the equation to find the velocity of pressure wave propogation?
What is the calulation for the pipe period and the calulations when combined with the Jakowski Head equations?
