tank fill rate

[Tassi Devil Diver]

How do you stay within the 60psi per minute fill rate when boosting oxygen with a double action booster? the Haskel I use from time to time boosts at the rate of around 5bar (70psi) per cycle with each cycle being a couple of seconds, a small KISS booster I also use from time to time fills at around the 60psi rate.

 

[cool_hardware52]

How do you stay within the 60psi per minute fill rate when boosting oxygen with a double action booster? the Haskel I use from time to time boosts at the rate of around 5bar (70psi) per cycle with each cycle being a couple of seconds, a small KISS booster I also use from time to time fills at around the 60psi rate.

You have three ways to control speed on a haskel, the flow rate of the drive gas, the pressure of the drive gas and the flow rate of the supply gas.

My haskels all have a pressure regulator and needle valve to control the drive gas, and my inlet whips have needle valves. Most of the time the supply gas whip is WFO, and the fill rate is a function of the drive gas needle valve and pressure reg.

Small RB bottles can be a problem as the volume of a single stroke of *any* booster, single action, double action etc. may cause an instantaneous increase in the bottle being filled that exceeds 1 psi / sec

Once can still adjust the variables to *average* 1 psi / sec.

 

[bl6394]

...

Small RB bottles can be a problem as the volume of a single stroke of *any* booster, single action, double action etc. may cause an instantaneous increase in the bottle being filled that exceeds 1 psi / sec

...

The 2L and 3L bottles are tough... With my Mini Haskell - I get 20-25 psi per cycle - when boosting from a full T cylinder ( ~ 2600 psi) of O2. Not much I can do but slow the cycle time of the booster.

There isn't as much of a pucker factor when filling from a 400 - 600 psi supply bottle - I will get 1-3 psi / cycle - but then the booster works harder and burns more drive gas. Not a perfect world either way.

 

[NAM001]

Just to toss something into the discussion . When fast filling tanks the inside is hotter than the outside of the tank. Al tanks are tempered at what 200 F and steel around 600F. So if you fast fill an al tank and the outside hits 150 then the inside is exceeding temper temperature and the metel temper is affected. If this is bogus some one say so. Also isnt the 10,000 fill test by the manufacturer done with water and not air where they can get say 10+ cycles per minute????? Looking to get educated here not to argue.

 

[bl6394]

Just to toss something into the discussion . When fast filling tanks the inside is hotter than the outside of the tank. Al tanks are tempered at what 200 F and steel around 600F. So if you fast fill an al tank and the outside hits 150 then the inside is exceeding temper temperature and the metel temper is affected. If this is bogus some one say so. Also isnt the 10,000 fill test by the manufacturer done with water and not air where they can get say 10+ cycles per minute????? Looking to get educated here not to argue.

Looking at Luxfer's mfg's recommendations on p 50. with respect to heat from the previously provided link:

heat effects on aluminum cylinders: Metals (e.g., iron/steel and aluminum) change properties when exposed to high temperatures. Aluminum cylinders exposed to fire, arc welding, ovens, furnaces and other heat sources will become easier to rupture. Aluminum cylinders known to have been exposed to heat sources over 350°F (175°C) are unsafe and must be condemned and removed from service. If you suspect a cylinder has been heated to temperatures between 265°F (130°C) and 350°F (175°C) it must be hydro-statically retested before further use. At no time should a cylinder be heated in order to cure or remove paint.

With a fast fill, the temperature of the gas will approach 700 degrees F. It will be somewhat less than the theoretical limit - as some of the heat will transfer immediately to the cylinder. However, assuming a fast fill - for a period of time - the gas contained in the cylinder will exceed the 265 / 350 temperature limit Luxfer established in their guide. Not the whole cylinder mind you - just the gas it contains.

The question an engineer might have: for the duration of time the gas contained in the cylinder is considerably above 350 - what sort of temperature gradient exists as the heat is transmitted from the gas to the exterior of the cylinder (e.g. how much of the interior cylinder wall is at or above 265). And during that period - how much temper of the cylinder walls is lost. And how many times can the manufacturer permit that to happen before the cylinder must be condemned?

These are all solvable problems (but perhaps not at this time of night.)

But what is the practical benefit? Any fast fills of this sort will have a considerable drop in pressure once the gas cools - and require either topping - or create an irritated customer with the short fill.

 

[cool_hardware52]

Looking at Luxfer's mfg's recommendations on p 50. with respect to heat from the previously provided link:

heat effects on aluminum cylinders: Metals (e.g., iron/steel and aluminum) change properties when exposed to high temperatures. Aluminum cylinders exposed to fire, arc welding, ovens, furnaces and other heat sources will become easier to rupture. Aluminum cylinders known to have been exposed to heat sources over 350°F (175°C) are unsafe and must be condemned and removed from service. If you suspect a cylinder has been heated to temperatures between 265°F (130°C) and 350°F (175°C) it must be hydro-statically retested before further use. At no time should a cylinder be heated in order to cure or remove paint.

With a fast fill, the temperature of the gas will approach 700 degrees F. It will be somewhat less than the theoretical limit - as some of the heat will transfer immediately to the cylinder. However, assuming a fast fill - for a period of time - the gas contained in the cylinder will exceed the 265 / 350 temperature limit Luxfer established in their guide. Not the whole cylinder mind you - just the gas it contains.

The question an engineer might have: for the duration of time the gas contained in the cylinder is considerably above 350 - what sort of temperature gradient exists as the heat is transmitted from the gas to the exterior of the cylinder (e.g. how much of the interior cylinder wall is at or above 265). And during that period - how much temper of the cylinder walls is lost. And how many times can the manufacturer permit that to happen before the cylinder must be condemned?

These are all solvable problems (but perhaps not at this time of night.)

But what is the practical benefit? Any fast fills of this sort will have a considerable drop in pressure once the gas cools - and require either topping - or create an irritated customer with the short fill.

Ok, I'll play. Apparently you still think the heat of compression can damage tanks.

Aluminum is hugely thermally conductive. ~2000+ times that of air. (The actual rate for air is dependent on density of the air )

That means trivial amount of *heat* the compressed air spreads very quickly to the entire tank. That means your "gradient" will be essentially zero from the inside of the tank to the outside.

News flash, a fast fill does *not* equal a house fire.......


Tobin

 

[bl6394]

Ok, I'll play. Apparently you still think the heat of compression can damage tanks.

Aluminum is hugely thermally conductive. ~2000+ times that of air. (The actual rate for air is dependent on density of the air )

That means trivial amount of *heat* the compressed air spreads very quickly to the entire tank. That means your "gradient" will be essentially zero from the inside of the tank to the outside.

News flash, a fast fill does *not* equal a house fire.......


Tobin

Tobin - to avoid making this seem like an argument - I'm going to avoid using patronizing phrases like "news flash" or "I'll play"

We understand that the standards for condemning a cylinder can be strict. E.g. CONDEMN all cylinders with surface cuts, digs or gouges in the metal that are either longer than six inches (152mm), or deeper than 0.030 inch (0.76 mm).

We agree that the aluminum alloy used in luxfer cylinders has as a thermal conductivity much greater than air, but it is a mistake to believe that this means that the cylinder wall is at a uniform temperature. You know this empirically when you touch a hot steel/aluminum skillet's handle. The egg may be frying - but because of the temperature gradient in the metal - the skillet handle is at a much lower temperature. There is actually a gradient in the temperature as we go from the inner cylinder wall facing a gas of 700F to the outer wall with a temperature of say 70F. See the following experiment for an example with rods. (52.09 -- Heat conduction in various metal rods)

So - if we understand that there is a temperature gradient that exists in the cylinder wall, perhaps -dT/dx = (T2-T1)/L). Does the possibility not exist that for a period of time some metal is above the tempering limit established by Luxfer?

It's been about 30 years since I've been a physics major - and my skills are beyond rusty. But perhaps someone else with sharper skills and more recent experience will chime in.

Again - let's try to avoid having an argument. Just trying to learn something.

 

[NAM001]

I have measured tank temperature (outside) and it continues to rise after the filling stops. to a point where the (I assume) the whole tank is equalized in temp. In short the inside is hot and the out side is cool. if the tank takes 10 min to xfer the inside heat to out side there will be a lag for some period. You can prove this by filling the tank and feeling the temp, (do a quick partial fill from 500-1500 in less than a minure and stop filling. the tank outside takes some time to warm. And there is always a resultant drop in temp when it cools. The greater the delta T of inside to outside is the faster the transfer happens. for a tank to go from 70- 120F outside in a few minutes sugests the inside is considerable higher at least in the short term. Perhaps the time involved is not great enough to effect the temper as so many claims.

 

[cool_hardware52]

We agree that the aluminum alloy used in luxfer cylinders has as a thermal conductivity much greater than air, but it is a mistake to believe that this means that the cylinder wall is at a uniform temperature. You know this empirically when you touch a hot steel/aluminum skillet's handle.

Please put an all aluminum pot on the stove. Fill it with water, and raise it to a boil.

Now pick it up by the aluminum handles with your bare hands.......


I weld all the time, tig, stainless steel, mild steel, and aluminum.

With stainless, which is a very poor conductor I often don't even wear gloves. Stainless is very easy to weld because the heat applied via the tig torch does not readily flow very far outside the area of the weld. I can safely manipulate the parts with my bare hands.

Mild steel is much the same, but is a bit more thermally conductive.

Aluminum is very different. Welding aluminum requires much more power because one must very quickly heat the area of the weld in order to cause localized melting, with insufficient power all that happens is the entire part warms up, but no local melting occurs.

Better have your gloves on too. Aluminum parts will often be hot enough to burn skin many feet away from the weld.

Tobin

 

[bl6394]

Please put an all aluminum pot on the stove. Fill it with water, and raise it to a boil.

Now pick it up by the aluminum handles with your bare hands.......


I weld all the time, tig, stainless steel, mild steel, and aluminum.

With stainless, which is a very poor conductor I often don't even wear gloves. Stainless is very easy to weld because the heat applied via the tig torch does not readily flow very far outside the area of the weld. I can safely manipulate the parts with my bare hands.

Mild steel is much the same, but is a bit more thermally conductive.

Aluminum is very different. Welding aluminum requires much more power because one must very quickly heat the area of the weld in order to cause localized melting, with insufficient power all that happens is the entire part warms up, but no local melting occurs.

Better have your gloves on too. Aluminum parts will often be hot enough to burn skin many feet away from the weld.

Tobin

Tobin - consider for a moment that the melting point of aluminum is 1,221°F. When you weld - you are raising that point to 1,221°F or higher - however, you've noticed that the entire object does not reach a temperature of 1,221°F. This is because a temperature gradient exists. Similarly, in the case we are discussing - there is a temperature gradient of some sort between the interior wall which is facing a gas of 700°F and the exterior wall which is facing room temperature.

And yes - I weld too. I'm sure not as much as you though. Oxy-Acetylene and Mig. lol. But frankly - I'm baffled... You almost seem emotionally connected to your position - and there can't really be any benefit to it? What is driving this irrational belief of yours?