# Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

14.

The hydraulic gradient line may be above or below the centre line of the pipe.

 [A]. True [B]. False

Answer: Option B

Explanation:

No answer description available for this question.

 Neel said: (Oct 20, 2013) Why the answer is false please give some explanation?

 Shibu.S said: (May 24, 2014) Pipeline system is materialized by the energy grade line. The hydraulic grade line is lower than the energy line by the velocity head.

 Bhargavi said: (Oct 14, 2014) 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.

 Zxc said: (Apr 18, 2015) 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.

 Zxc said: (Apr 18, 2015) 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.

 Rahul said: (Nov 9, 2015) Also in case of pump.

 Rajat Ojha said: (Nov 8, 2016) As per my knowledge, True is the correct answer.

 Dhaval said: (Dec 30, 2016) I think, true is the correct answer.

 Tatarao said: (Feb 4, 2017) True is the correct answer. I too agree.

 Nisad said: (Jun 13, 2017) 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?

 Aniket said: (Jul 5, 2017) It should be above or below HGL.

 Aman Patel said: (Nov 29, 2017) According to me, True is the right answer.

 Anil Khalate said: (Dec 19, 2017) False, because HGL Is always Above the Mean line By Velocity Head V2/2g.

 Aniket said: (Dec 24, 2017) Hgl is above the center line because it is the addition of pressure head & static head.

 Bhanu Yadav said: (Jan 21, 2018) True is the correct answer.

 Ganesh Rawal said: (Feb 10, 2018) Yes, true is the correct answer.

 S Rama Rao said: (Apr 10, 2018) 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.

 Pavankale said: (Jun 1, 2018) 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?

 Vernon Pe said: (Aug 19, 2018) It is True, due to existence of positive and negative pressure.

 Chandrootam said: (Jan 23, 2019) 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.

 Pratik said: (Sep 14, 2019) Well HGL is static head + pressure head, so it can be below the center line of pipe, right?

 Vishal said: (Nov 18, 2019) HGL always above the centre line of pipe.

 Sawan Gupta said: (Dec 9, 2019) 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.

 Vinay Bel said: (Oct 20, 2020) Yes, true is the correct answer.

 Joy said: (Oct 31, 2020) True is the right answer.

 Jivan said: (Jan 23, 2021) In case of open channel, HGL coincides with water surface.

 Kartik said: (Feb 18, 2021) True is the correct answer.

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