Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion
Discussion Forum : Hydraulics and Fluid Mechanics - Section 2 (Q.No. 14)
14.
The hydraulic gradient line may be above or below the centre line of the pipe.
Discussion:
27 comments Page 1 of 3.
Sawan gupta said:
6 years ago
The HGL should always lie above the profile. If it does not, the water may still flow but in sections where the profile lies above the gradient, a negative pressure ensues that can cause air or contaminants to enter the pipeline. Sections of the pipeline where negative pressures occur should be redesigned.
ZXC said:
1 decade ago
At points where the HGL passes through the center line of the pipe, the pressure is zero. If the pipe lies above the HGL, there is a vacuum in the pipe, a condition that is often avoided, if possible, in the design of piping systems; an exception would be in the design of a siphon.
ZXC said:
1 decade ago
In general, if the HGL is above the crown of the pipe, pressure flow hydraulic calculations are appropriate. Conversely, if the HGL is below the crown of the pipe, open channel flow calculations are appropriate.
Nisad said:
8 years ago
The central line of the pipe will give only static head but hydraulic gradient line will give static head+pressure head so I think hydraulic gradient line must above the pipe central line. Am I right?
Bhargavi said:
1 decade ago
For positive pressure in the pipe, the H.G.L. is above the centre line of pipe and for negative pressure in the pipe, H.G.L. is below the centre line of the pipe. So I think True is correct answer.
Pavankale said:
7 years ago
What if I select datum line such that it is half above the centre line and half belelow the centre line and pipe is inclined then HGL line may come below centre line?
Chandrootam said:
7 years ago
It may be vacuum pressure at a point inside the pipe, example -in case of flow through internal or external mouthpiece when flow head is more than 7.5m.
S Rama Rao said:
7 years ago
Hydraulic gradient line is always above the centre line of the pipe. It will never below the centre line of the pipe. So the answer is false.
SHIBU.S said:
1 decade ago
Pipeline system is materialized by the energy grade line. The hydraulic grade line is lower than the energy line by the velocity head.
Aniket said:
8 years ago
Hgl is above the center line because it is the addition of pressure head & static head.
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