Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

20. 

The liquid used in manometers should have

[A]. low density
[B]. high density
[C]. low surface tension
[D]. high surface tension

Answer: Option D

Explanation:

No answer description available for this question.

Venkat said: (Jul 2, 2015)  
Should have high density to decrease the column height and due to which we can measure more range of pressure.

Kaushal said: (Aug 9, 2015)  
It should be of high density.

Nadim said: (Oct 3, 2015)  
Should have liquid surface tension so that unnecessary rise can be avoided. Am I correct please comment.

Aakash Gupta said: (Jan 14, 2016)  
Should have high density so that the height of column can be reduced. Because the manometers are used for high pressure measurement so it is important to make the column height in practical limit.

Ahmed said: (Mar 24, 2016)  
Characteristics of liquid used in U-tube Manometer:

1. Low viscosity.
2. Low surface tension.
3. Liquid should have a high boiling point and should not get vaporized.
4. The liquid should stick to the walls of the tube.

Wiki said: (Oct 9, 2016)  
Should have low surface tension. But density should be high in order to decrease column length.

Apcivilian said: (Dec 6, 2016)  
It should be low surface tension.

Pvdatt said: (Feb 8, 2017)  
Density of fluid selection depends upon the pressure of the liquid system. If we choose low-density fluid we can measure small changes in pressure. If we choose high density we can measure larger pressure difference.

Although the increase in density leads to the reduction in accuracy of the manometer.

Low surface tension is a desirable property.

Muhammad Waqas said: (Feb 25, 2017)  
Yes, 100 % correct @Pvdatt.

One thing, I would like to add is if the manometer liquid has high surface tension then the liquid surface in a tube will be in a shape of the dome it wouldn't be flat so we can't measure a correct reading that's why liquid should have low surface tension.

@Nadim.

The diameter of the tube is large enough to avoid the capillary effect. The Surface tension of the liquid in large diameter tube has nothing to do with the capillary effect.

Vinit said: (Jun 13, 2017)  
Desirable properties of good manometric liquid should have;

-> Low-freezing point.
-> High boiling point.
-> Non wetting characteristics.
-> Low surface tension.
-> Chemically inert.
-> Clear visible interface.
-> Ability to maintain density at various temperatures.

Ritwick said: (Jul 7, 2017)  
You are right, Thanks @Vinit.

Yogendra said: (Aug 16, 2017)  
Why high surface tension required?

Pascal said: (Sep 16, 2017)  
@Vinit.

Non-wetting and low surface tension are contradictory.

Rajasekhar said: (Nov 24, 2017)  
Higher surface tension enables less wetting of the tube and so these type of liquids are desirable in manimeters.

C.R.Meena said: (Nov 30, 2017)  
High density is the correct answer.

Durugappa said: (Dec 5, 2017)  
It should low surface tension.

Nitin Dhasmana said: (Jan 11, 2018)  
Then why we use mercury as a manometric fluid?

I think the given answer is correct.

Rinku Meena said: (Jan 19, 2018)  
High density is correct.

Vijay Rajput said: (Mar 25, 2018)  
High density is the correct.

Rishu said: (Jun 7, 2018)  
Manometer liquid should have high density and low vapour pressure.

Khushal said: (Jun 26, 2018)  
Why low surface tension is required? Please explain in detail.

Mukesh Piploda said: (Jul 20, 2018)  
Surface tension should be high because higher surface tension gives low vapor pressure (i.e. No vapor formation takes place of manometric fluid) and also high surface tension prevents the unnecessary rise of fluid in Fluid column due to adhesion during pressure measurement.

Ganesh.M said: (Jul 28, 2018)  
@Ahmed.

The Liquid should Stick the walls of tube-- represents high surface tension.

Asad Hayat said: (Sep 24, 2019)  
Manometric fluids should have the following properties

* High density (for high-pressure measurement the rise of liquid will be within reasonable limits)
* Low Surface tension.
* Low Viscosity (As high viscosity will slow down the sensitivity or responsiveness of fluid movement).
* Low Vapour Pressure (Because, if Vapour pressure is greater than the fluid pressure to be measured then the problem of cavitation will arise.).
* High Boiling point.
* Low Freezing Point.
* Chemically Inert.
* Distinct Interface.

Pravin Manohar said: (Jan 8, 2020)  
Low surface tension and high density.

Prem said: (Aug 25, 2020)  
Desirable properties of good manometric liquid should have;
-> Low-freezing point.
-> High boiling point.
-> Non-wetting characteristics.
-> Low surface tension.
-> Chemically inert.
-> Clear visible interface.
-> Ability to maintain density at various temperatures.

Pallab Dey said: (Sep 5, 2020)  
Manometric fluids should have the following properties:

* High density ( for high-pressure measurement the rise of liquid will be within reasonable limits).
* Low Viscosity (As high viscosity will slow down the sensitivity or responsiveness of fluid movement).
* Low Vapour Pressure (Because, if Vapour pressure is greater than the fluid pressure to be measured then the problem of cavitation will arise).
* High Boiling point.
* Low Freezing Point.
* Low Surface tension.
* Chemically Inert.
* Distinct Interface.

Vinay Bel said: (Oct 21, 2020)  
Low surface tension and high density.

Vinay Bel said: (Oct 24, 2020)  
Low density is the right option.

Vinay Bel said: (Oct 24, 2020)  
Low surface tension and high density.

Tushar said: (Dec 12, 2020)  
Only two property high,

1. High density.
2. High boiling point.

Other than all property should low.

Kisshor said: (Dec 17, 2020)  
It should be low surface tension due to surface there will be rise or fall of liquid depending upon the contact angle and reading may be less accurate.

Sooraj said: (Dec 24, 2020)  
The diameter of manometer will be such that capillarity will not be seen. So what is the point in discussing about surface tension?

Suhail Rehman said: (Feb 7, 2021)  
The right answer is High surface tension.

Inder said: (Jun 11, 2021)  
It should be high density and low vapour pressure.

Bhatu Arjun said: (Jun 17, 2021)  
Mercury used in manometer and it has high sufrace tention property.

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