blacknet
Contributor
Hello,
Anyone know the formula to convert cubic feet to liters for tanks?
Ed
Anyone know the formula to convert cubic feet to liters for tanks?
Ed
Cuft to liter conversion
- Thread starter blacknet
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It's sort of an apples & oranges comparison.
Liter ratings are for unpressurized volume, while CF ratings are for how much gas a cylinder holds when pressurized.
For example, a LP steel 11 liter tank is a 72 CF tank, while a standard AL 11 liter tank is an 80 CF tank, and a HP steel 11 liter tank is a 95 CF tank (approx).
Add to that that the CF rating on a tank isn't necessarily exactly at its working pressure (for example, a standard AL 80 has a working pressure of 3000 psi, but to get 80 CF in there you have to pump it to 3100)(holds 77.4 CF at 3000).
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On the one hand, the liter rating is a more accurate measurement of the actual inner volume of the tank - but as we breathe air, the CF rating is more useful in expressing how much gas the tank holds when it's full.
Rick
Liter ratings are for unpressurized volume, while CF ratings are for how much gas a cylinder holds when pressurized.
For example, a LP steel 11 liter tank is a 72 CF tank, while a standard AL 11 liter tank is an 80 CF tank, and a HP steel 11 liter tank is a 95 CF tank (approx).
Add to that that the CF rating on a tank isn't necessarily exactly at its working pressure (for example, a standard AL 80 has a working pressure of 3000 psi, but to get 80 CF in there you have to pump it to 3100)(holds 77.4 CF at 3000).
-----------
On the one hand, the liter rating is a more accurate measurement of the actual inner volume of the tank - but as we breathe air, the CF rating is more useful in expressing how much gas the tank holds when it's full.
Rick
I know Rick knows this,
And Ed I wonder if you were sleeping in your basic scuba classes.
The internal volume of a tank is usually expressed in liters. The internal volume of a tank will not change with pressure. So the ft^3 rating you see is the amount of free air delivered at 1 atmosphere. e.g. A Luxfer Al80 has an internal volume of 11.11 liters. When filled to 3000 psig it will deliver 77.4 cubic feet of air at one atmosphere. The volume of the tank is 11.11 L at 14.7 psia and is 11.11 at 3000 psig (neglecting the deformation of the metal under stress). You can determine this with the appropriate gas law relationships. For a straight conversion of metric units to imperial units the liter is 0.03531467 ft^3.
And Ed I wonder if you were sleeping in your basic scuba classes.
The internal volume of a tank is usually expressed in liters. The internal volume of a tank will not change with pressure. So the ft^3 rating you see is the amount of free air delivered at 1 atmosphere. e.g. A Luxfer Al80 has an internal volume of 11.11 liters. When filled to 3000 psig it will deliver 77.4 cubic feet of air at one atmosphere. The volume of the tank is 11.11 L at 14.7 psia and is 11.11 at 3000 psig (neglecting the deformation of the metal under stress). You can determine this with the appropriate gas law relationships. For a straight conversion of metric units to imperial units the liter is 0.03531467 ft^3.
OP
blacknet
Contributor
Hello,
No I wasn't asleep durring my "ow" class. I don't know where your at but here we don't use liters
Also don't assume that i'm refering to al80 tanks either.
Also thanks for the insight.
Ed
No I wasn't asleep durring my "ow" class. I don't know where your at but here we don't use liters
Also don't assume that i'm refering to al80 tanks either.Also thanks for the insight.
Ed
e.g. is an abbreviation for 'exempli gratia' which means: for example
To but it bluntly the use of an AL80 was an example.
I am in the US ED and we do us liters, grams, cm as well as gallon, feet, pounds. I know that this stuff is taught in OW because my kids know it.
I am sorry that the backwaters of Alabama/Georgia from whence you hail is lacking in the ability to provide you a proper education.
omar
To but it bluntly the use of an AL80 was an example.
I am in the US ED and we do us liters, grams, cm as well as gallon, feet, pounds. I know that this stuff is taught in OW because my kids know it.
I am sorry that the backwaters of Alabama/Georgia from whence you hail is lacking in the ability to provide you a proper education.
omar
OP
blacknet
Contributor
Hello,
So where are you at in the us? And what ow cert agency teaches this?
Ed
So where are you at in the us? And what ow cert agency teaches this?
Ed
OP
blacknet
Contributor
Hello,
So once again, what's that formula?
Ed
So once again, what's that formula?
Ed
ED,
Air is a gas. Gases have various properties that we can observe including pressure (p), temperature (T), mass (m), and volume (V) that contains the gas. Careful, scientific observation has determined that these variables are related to one another, and the values of these properties determine the state of the gas.
If we fix any two of the properties we can determine the nature of the relationship between the other two. If the pressure and temperature are held constant, the volume of the gas depends directly on the mass, or amount of gas. This allows us to define a single additional property called the gas density (r), which is the ratio of mass to volume.
If the mass and temperature are held constant, the product of the pressure and volume are observed to be nearly constant for a real gas. (The product of pressure and volume is exactly a constant for an ideal gas.) This relationship between pressure and volume is called Boyle's Law in honor of Robert Boyle who first observed it in 1660. You will see this as (p1*V1 = p2*V2).
Finally, if the mass and pressure are held constant, the volume is directly proportional to the temperature for an ideal gas. This relationship is called Charles and Gay-Lussac's Law in honor of the two French scientists who discovered the relationship. You will see this as (p1/T1)=(p2/T2).
The gas laws of Boyle and Charles and Gay-Lussac can be combined into a single equation of state (p * V / T = n * R) where * denotes multiplication and / denotes division. To account for the effects of mass, a universal constant (R) has been defined and the mass of the gas is expressed in moles (n). Performing a little algebra, we obtain the more familiar form (p * V) = (n * R * T) or the ideal gas law.
PADI
Your really need some remedial instruction.
omar
Air is a gas. Gases have various properties that we can observe including pressure (p), temperature (T), mass (m), and volume (V) that contains the gas. Careful, scientific observation has determined that these variables are related to one another, and the values of these properties determine the state of the gas.
If we fix any two of the properties we can determine the nature of the relationship between the other two. If the pressure and temperature are held constant, the volume of the gas depends directly on the mass, or amount of gas. This allows us to define a single additional property called the gas density (r), which is the ratio of mass to volume.
If the mass and temperature are held constant, the product of the pressure and volume are observed to be nearly constant for a real gas. (The product of pressure and volume is exactly a constant for an ideal gas.) This relationship between pressure and volume is called Boyle's Law in honor of Robert Boyle who first observed it in 1660. You will see this as (p1*V1 = p2*V2).
Finally, if the mass and pressure are held constant, the volume is directly proportional to the temperature for an ideal gas. This relationship is called Charles and Gay-Lussac's Law in honor of the two French scientists who discovered the relationship. You will see this as (p1/T1)=(p2/T2).
The gas laws of Boyle and Charles and Gay-Lussac can be combined into a single equation of state (p * V / T = n * R) where * denotes multiplication and / denotes division. To account for the effects of mass, a universal constant (R) has been defined and the mass of the gas is expressed in moles (n). Performing a little algebra, we obtain the more familiar form (p * V) = (n * R * T) or the ideal gas law.
PADI
Your really need some remedial instruction.
omar
OP
blacknet
Contributor
Hello,
no no, you missed the entire point of what I was getting at. (know those gas laws and they was covered in ow) You should re-read what I wrote and quit trying to talk down to me and second guess what i'm doing.
Ed
no no, you missed the entire point of what I was getting at. (know those gas laws and they was covered in ow) You should re-read what I wrote and quit trying to talk down to me and second guess what i'm doing.
Ed
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