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Where is the right place to put the pressure gauge to measure the pressure of a tank?
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Studying the basic concepts of Fluid Mechanics, applied to pressure gauges, and looking at schematics in many places, a question came into my mind: Where is the right place to put the pressure gauge to measure the pressure of a tank?
                          
The first case would be if the tank contains a gas. In this situation, Çengel's Fluid Mechanics book clarified it to me:
Since the gravitational effects of gases are negligible, the pressure anywhere in the tank and at position 1 has the same value.
                                           Â
Thus, I can put it anywhere in the tank if it contains a gas.
The second case would be if the tank contains a liquid, especially when the tank is large. In this situation, the decision that seems more logical to me is to put the pressure gauge in the bottom of the tank. However, in all the places that I looked, the point "A" was the chosen one to measure pressure (as shown in the images below in points M, N, A and B), which I believe that gives the average pressure of the tank because the point is located at height of its geometric center:
$$p_average=frac1H cdotint_0^Hgamma h ,dh=fracgamma H2=p_A$$
    Images sources: MATHalino/PennState College of Engineering (MNE)/The SensorsGuide/University of Sydney (MDP)/ScienceStruck/Chegg
So, where is the right place to put it to measure pressure of a tank? Why the points M/N/A/B were chosen instead of the botton of their tanks to calculate the pressure in the images above?
pressure fluid-statics
asked 1 hour ago
Vinicius ACP
336
add a comment |Â
up vote
2
down vote
favorite
Studying the basic concepts of Fluid Mechanics, applied to pressure gauges, and looking at schematics in many places, a question came into my mind: Where is the right place to put the pressure gauge to measure the pressure of a tank?
                         Â
The first case would be if the tank contains a gas. In this situation, Çengel's Fluid Mechanics book clarified it to me:
Since the gravitational effects of gases are negligible, the pressure anywhere in the tank and at position 1 has the same value.
                                           Â
Thus, I can put it anywhere in the tank if it contains a gas.
The second case would be if the tank contains a liquid, especially when the tank is large. In this situation, the decision that seems more logical to me is to put the pressure gauge in the bottom of the tank. However, in all the places that I looked, the point "A" was the chosen one to measure pressure (as shown in the images below in points M, N, A and B), which I believe that gives the average pressure of the tank because the point is located at height of its geometric center:
$$p_average=frac1H cdotint_0^Hgamma h ,dh=fracgamma H2=p_A$$
    Images sources: MATHalino/PennState College of Engineering (MNE)/The SensorsGuide/University of Sydney (MDP)/ScienceStruck/Chegg
So, where is the right place to put it to measure pressure of a tank? Why the points M/N/A/B were chosen instead of the botton of their tanks to calculate the pressure in the images above?
pressure fluid-statics
asked 1 hour ago
Vinicius ACP
336
2
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
– David White
1 hour ago
@DavidWhite Please consider converting that to an answer.
– rob♦
16 mins ago
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
Studying the basic concepts of Fluid Mechanics, applied to pressure gauges, and looking at schematics in many places, a question came into my mind: Where is the right place to put the pressure gauge to measure the pressure of a tank?
                         Â
The first case would be if the tank contains a gas. In this situation, Çengel's Fluid Mechanics book clarified it to me:
Since the gravitational effects of gases are negligible, the pressure anywhere in the tank and at position 1 has the same value.
                                           Â
Thus, I can put it anywhere in the tank if it contains a gas.
The second case would be if the tank contains a liquid, especially when the tank is large. In this situation, the decision that seems more logical to me is to put the pressure gauge in the bottom of the tank. However, in all the places that I looked, the point "A" was the chosen one to measure pressure (as shown in the images below in points M, N, A and B), which I believe that gives the average pressure of the tank because the point is located at height of its geometric center:
$$p_average=frac1H cdotint_0^Hgamma h ,dh=fracgamma H2=p_A$$
    Images sources: MATHalino/PennState College of Engineering (MNE)/The SensorsGuide/University of Sydney (MDP)/ScienceStruck/Chegg
So, where is the right place to put it to measure pressure of a tank? Why the points M/N/A/B were chosen instead of the botton of their tanks to calculate the pressure in the images above?
pressure fluid-statics
asked 1 hour ago
Vinicius ACP
336
Studying the basic concepts of Fluid Mechanics, applied to pressure gauges, and looking at schematics in many places, a question came into my mind: Where is the right place to put the pressure gauge to measure the pressure of a tank?
                         Â
The first case would be if the tank contains a gas. In this situation, Çengel's Fluid Mechanics book clarified it to me:
Since the gravitational effects of gases are negligible, the pressure anywhere in the tank and at position 1 has the same value.
                                           Â
Thus, I can put it anywhere in the tank if it contains a gas.
The second case would be if the tank contains a liquid, especially when the tank is large. In this situation, the decision that seems more logical to me is to put the pressure gauge in the bottom of the tank. However, in all the places that I looked, the point "A" was the chosen one to measure pressure (as shown in the images below in points M, N, A and B), which I believe that gives the average pressure of the tank because the point is located at height of its geometric center:
$$p_average=frac1H cdotint_0^Hgamma h ,dh=fracgamma H2=p_A$$
    Images sources: MATHalino/PennState College of Engineering (MNE)/The SensorsGuide/University of Sydney (MDP)/ScienceStruck/Chegg
So, where is the right place to put it to measure pressure of a tank? Why the points M/N/A/B were chosen instead of the botton of their tanks to calculate the pressure in the images above?
pressure fluid-statics
pressure fluid-statics
asked 1 hour ago
Vinicius ACP
336
asked 1 hour ago
Vinicius ACP
336
asked 1 hour ago
Vinicius ACP
336
asked 1 hour ago
Vinicius ACP
336
asked 1 hour ago
Vinicius ACP
336
336
2
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
– David White
1 hour ago
@DavidWhite Please consider converting that to an answer.
– rob♦
16 mins ago
add a comment |Â
2
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
– David White
1 hour ago
@DavidWhite Please consider converting that to an answer.
– rob♦
16 mins ago
2
2
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
– David White
1 hour ago
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
– David White
1 hour ago
@DavidWhite Please consider converting that to an answer.
– rob♦
16 mins ago
@DavidWhite Please consider converting that to an answer.
– rob♦
16 mins ago
add a comment |Â
3 Answers
3
active
oldest
votes
up vote
3
down vote
In general, there is no "pressure" to measure, because pressure is a field with one pressure at each place. You can measure the pressure anywhere you like, and that will be a correct measurement of the pressure at that location. Often there is only one system variable (head if the tank is open to the atmosphere, system pressure if it is compressed), which means that given one pressure measurement the pressure anywhere else can be solved for. Of course there are some engineering motivations for choosing some spots over others.
If you don't put it at the bottom, your gauge will quit working whenever the tank level drops below wherever you mounted it. In real engineering situations, when the bottom of the tank has a complicated shape (due to submerged equipment for example) it can simplify things to put the gauge above the "complicated" volume so that the fluid above the gauge always has a simple shape.
answered 1 hour ago
Display Name
1557
+1 But I think you might clarify the first sentence to say that in general there is not just one single pressure; the pressure varies from point to point. This is implied by calling it a "field" but that usage might be unfamiliar to someone asking this kind of question.
– Mike
1 hour ago
That's a good point. I edited the comment.
– Display Name
1 hour ago
add a comment |Â
up vote
1
down vote
Unlike a sensor, a gauge has to be where you can see it. Often you dont want the process liquid to get in the gauge, so the gauge is on top of the liquid level.
answered 56 mins ago
Manu de Hanoi
1879
add a comment |Â
up vote
1
down vote
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
answered 10 mins ago
David White
3,5171517
add a comment |Â
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
In general, there is no "pressure" to measure, because pressure is a field with one pressure at each place. You can measure the pressure anywhere you like, and that will be a correct measurement of the pressure at that location. Often there is only one system variable (head if the tank is open to the atmosphere, system pressure if it is compressed), which means that given one pressure measurement the pressure anywhere else can be solved for. Of course there are some engineering motivations for choosing some spots over others.
If you don't put it at the bottom, your gauge will quit working whenever the tank level drops below wherever you mounted it. In real engineering situations, when the bottom of the tank has a complicated shape (due to submerged equipment for example) it can simplify things to put the gauge above the "complicated" volume so that the fluid above the gauge always has a simple shape.
answered 1 hour ago
Display Name
1557
+1 But I think you might clarify the first sentence to say that in general there is not just one single pressure; the pressure varies from point to point. This is implied by calling it a "field" but that usage might be unfamiliar to someone asking this kind of question.
– Mike
1 hour ago
That's a good point. I edited the comment.
– Display Name
1 hour ago
add a comment |Â
up vote
3
down vote
In general, there is no "pressure" to measure, because pressure is a field with one pressure at each place. You can measure the pressure anywhere you like, and that will be a correct measurement of the pressure at that location. Often there is only one system variable (head if the tank is open to the atmosphere, system pressure if it is compressed), which means that given one pressure measurement the pressure anywhere else can be solved for. Of course there are some engineering motivations for choosing some spots over others.
If you don't put it at the bottom, your gauge will quit working whenever the tank level drops below wherever you mounted it. In real engineering situations, when the bottom of the tank has a complicated shape (due to submerged equipment for example) it can simplify things to put the gauge above the "complicated" volume so that the fluid above the gauge always has a simple shape.
answered 1 hour ago
Display Name
1557
+1 But I think you might clarify the first sentence to say that in general there is not just one single pressure; the pressure varies from point to point. This is implied by calling it a "field" but that usage might be unfamiliar to someone asking this kind of question.
– Mike
1 hour ago
That's a good point. I edited the comment.
– Display Name
1 hour ago
add a comment |Â
up vote
3
down vote
up vote
3
down vote
In general, there is no "pressure" to measure, because pressure is a field with one pressure at each place. You can measure the pressure anywhere you like, and that will be a correct measurement of the pressure at that location. Often there is only one system variable (head if the tank is open to the atmosphere, system pressure if it is compressed), which means that given one pressure measurement the pressure anywhere else can be solved for. Of course there are some engineering motivations for choosing some spots over others.
If you don't put it at the bottom, your gauge will quit working whenever the tank level drops below wherever you mounted it. In real engineering situations, when the bottom of the tank has a complicated shape (due to submerged equipment for example) it can simplify things to put the gauge above the "complicated" volume so that the fluid above the gauge always has a simple shape.
answered 1 hour ago
Display Name
1557
In general, there is no "pressure" to measure, because pressure is a field with one pressure at each place. You can measure the pressure anywhere you like, and that will be a correct measurement of the pressure at that location. Often there is only one system variable (head if the tank is open to the atmosphere, system pressure if it is compressed), which means that given one pressure measurement the pressure anywhere else can be solved for. Of course there are some engineering motivations for choosing some spots over others.
If you don't put it at the bottom, your gauge will quit working whenever the tank level drops below wherever you mounted it. In real engineering situations, when the bottom of the tank has a complicated shape (due to submerged equipment for example) it can simplify things to put the gauge above the "complicated" volume so that the fluid above the gauge always has a simple shape.
answered 1 hour ago
Display Name
1557
edited 1 hour ago
answered 1 hour ago
Display Name
1557
answered 1 hour ago
Display Name
1557
answered 1 hour ago
Display Name
1557
1557
+1 But I think you might clarify the first sentence to say that in general there is not just one single pressure; the pressure varies from point to point. This is implied by calling it a "field" but that usage might be unfamiliar to someone asking this kind of question.
– Mike
1 hour ago
That's a good point. I edited the comment.
– Display Name
1 hour ago
add a comment |Â
+1 But I think you might clarify the first sentence to say that in general there is not just one single pressure; the pressure varies from point to point. This is implied by calling it a "field" but that usage might be unfamiliar to someone asking this kind of question.
– Mike
1 hour ago
That's a good point. I edited the comment.
– Display Name
1 hour ago
+1 But I think you might clarify the first sentence to say that in general there is not just one single pressure; the pressure varies from point to point. This is implied by calling it a "field" but that usage might be unfamiliar to someone asking this kind of question.
– Mike
1 hour ago
+1 But I think you might clarify the first sentence to say that in general there is not just one single pressure; the pressure varies from point to point. This is implied by calling it a "field" but that usage might be unfamiliar to someone asking this kind of question.
– Mike
1 hour ago
That's a good point. I edited the comment.
– Display Name
1 hour ago
That's a good point. I edited the comment.
– Display Name
1 hour ago
add a comment |Â
up vote
1
down vote
Unlike a sensor, a gauge has to be where you can see it. Often you dont want the process liquid to get in the gauge, so the gauge is on top of the liquid level.
answered 56 mins ago
Manu de Hanoi
1879
add a comment |Â
up vote
1
down vote
Unlike a sensor, a gauge has to be where you can see it. Often you dont want the process liquid to get in the gauge, so the gauge is on top of the liquid level.
answered 56 mins ago
Manu de Hanoi
1879
add a comment |Â
up vote
1
down vote
up vote
1
down vote
Unlike a sensor, a gauge has to be where you can see it. Often you dont want the process liquid to get in the gauge, so the gauge is on top of the liquid level.
answered 56 mins ago
Manu de Hanoi
1879
Unlike a sensor, a gauge has to be where you can see it. Often you dont want the process liquid to get in the gauge, so the gauge is on top of the liquid level.
answered 56 mins ago
Manu de Hanoi
1879
answered 56 mins ago
Manu de Hanoi
1879
answered 56 mins ago
Manu de Hanoi
1879
answered 56 mins ago
Manu de Hanoi
1879
1879
add a comment |Â
add a comment |Â
up vote
1
down vote
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
answered 10 mins ago
David White
3,5171517
add a comment |Â
up vote
1
down vote
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
answered 10 mins ago
David White
3,5171517
add a comment |Â
up vote
1
down vote
up vote
1
down vote
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
answered 10 mins ago
David White
3,5171517
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
answered 10 mins ago
David White
3,5171517
answered 10 mins ago
David White
3,5171517
answered 10 mins ago
David White
3,5171517
answered 10 mins ago
David White
3,5171517
3,5171517
add a comment |Â
add a comment |Â
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2
The location depends on why you are measuring the pressure. There will be a process reason for the pressure measurement, and that will determine the location of the pressure measuring device. Ex: it's possible to infer tank level from pressure. In that case, you probably want the pressure measurement at the bottom of the tank. On the other hand, if you are worried about something in the vapor space of the tank, you want the pressure measurement on the top of the tank.
– David White
1 hour ago
@DavidWhite Please consider converting that to an answer.
– rob♦
16 mins ago