Where is it safe to store 1lb propane cylinders for a Magma grill?

[Henry Boyd]

+1 :smt038:smt038 The cheaper the hair spray the better!

I thought starting ether was the propellant of choice.

 

[Greg]

Ether! wow, I've always used hairspray. I did try spray deoderant once.

Here are some others you can try...

http://www.aaroncake.net/spuds/boom.asp

 

[JVM225]

Not sure off hand what the maximum pressure is but I remember reading the label at Home Depot. It is intended to be used by plumbers to test for leaks under pressure as they lay a pipe line.
View attachment 20259

Jack,

I really like that set up. Would it be possible for you to post a parts/assembly list? The Sea Ray logo is a nice touch too.

 

[MonacoMike]

Not sure off hand what the maximum pressure is but I remember reading the label at Home Depot. It is intended to be used by plumbers to test for leaks under pressure as they lay a pipe line.
View attachment 20259

What are the cubic inches and PSI of a 1lb tank? Net cubic inches of the proposed holder? The canister is far larger than the tank so PSI will be far lower. How much???

 

[Henry Boyd]

What are the cubic inches and PSI of a 1lb tank? Net cubic inches of the proposed holder? The canister is far larger than the tank so PSI will be far lower. How much???

My chemistry/physics is as good as it used to be. So if somebody has a better grasp on the science, please feel free to jump in. Propane is mostly in a liquid state in the tank. It converts to gas as the valve is opened and the pressure in the tank drops to atmospheric. As I recall at 100 degrees F propane gas compresses to liquid at slightly less than 200 PSI. So the tanks have to have a pressure rating of at least 200 PSI, if not more. The transition from liquid to gas is temperature dependent and I don't know how much the pressure would change in relation to the temperature change. Obviously as the temperature increases, so does pressure (throw a propane tank on a fire and it ruptures and explodes).

That also seems to suggest that a tank container to be effective would also have a pressure rating of 200 PSI plus at 100 degrees, because at that point the gas would begin to convert to liquid and the pressure would begin to hold steady. To figure out what the max pressure of the container would have to be we'd have to figure out the transition pressure for the normal temperature range the tank in container would see in service.

Henry

 

[Henry Boyd]

That was supposed to be not as good

 

[matthewmiller01]

My chemistry/physics is as good as it used to be. So if somebody has a better grasp on the science, please feel free to jump in. Propane is mostly in a liquid state in the tank. It converts to gas as the valve is opened and the pressure in the tank drops to atmospheric. As I recall at 100 degrees F propane gas compresses to liquid at slightly less than 200 PSI. So the tanks have to have a pressure rating of at least 200 PSI, if not more. The transition from liquid to gas is temperature dependent and I don't know how much the pressure would change in relation to the temperature change. Obviously as the temperature increases, so does pressure (throw a propane tank on a fire and it ruptures and explodes).

That also seems to suggest that a tank container to be effective would also have a pressure rating of 200 PSI plus at 100 degrees, because at that point the gas would begin to convert to liquid and the pressure would begin to hold steady. To figure out what the max pressure of the container would have to be we'd have to figure out the transition pressure for the normal temperature range the tank in container would see in service.

Henry

But the max pressure of the storage container wouldn't have to be as high as the cylinder's max pressure since, for the same amount of gas in a larger volume, the pressure would be lower. I don't know if propane follows the Ideal Gas Law or not (probably not), but I think you could get rough numbers from it. Of course, building the storage container to the same max pressure spec as the bottles would give you margin from it's actual rupture pressure.

 

[MonacoMike]

My chemistry/physics is as good as it used to be. So if somebody has a better grasp on the science, please feel free to jump in. Propane is mostly in a liquid state in the tank. It converts to gas as the valve is opened and the pressure in the tank drops to atmospheric. As I recall at 100 degrees F propane gas compresses to liquid at slightly less than 200 PSI. So the tanks have to have a pressure rating of at least 200 PSI, if not more. The transition from liquid to gas is temperature dependent and I don't know how much the pressure would change in relation to the temperature change. Obviously as the temperature increases, so does pressure (throw a propane tank on a fire and it ruptures and explodes).

That also seems to suggest that a tank container to be effective would also have a pressure rating of 200 PSI plus at 100 degrees, because at that point the gas would begin to convert to liquid and the pressure would begin to hold steady. To figure out what the max pressure of the container would have to be we'd have to figure out the transition pressure for the normal temperature range the tank in container would see in service.

Henry

But the max pressure of the storage container wouldn't have to be as high as the cylinder's max pressure since, for the same amount of gas in a larger volume, the pressure would be lower. I don't know if propane follows the Ideal Gas Law or not (probably not), but I think you could get rough numbers from it. Of course, building the storage container to the same max pressure spec as the bottles would give you margin from it's actual rupture pressure.

You guys are outta my league. :smt038 :smt100

 

[Henry Boyd]

But the max pressure of the storage container wouldn't have to be as high as the cylinder's max pressure since, for the same amount of gas in a larger volume, the pressure would be lower. I don't know if propane follows the Ideal Gas Law or not (probably not), but I think you could get rough numbers from it. Of course, building the storage container to the same max pressure spec as the bottles would give you margin from it's actual rupture pressure.

I don't think you can use the ideal gas laws, or rather apply it in a formula that doesn't involve calculus because you're not dealing with a constant gas volume. As the pressure changes (drops) more gas volume is created as more propane molecules transition from liquid to gas.

A leak in the cylinder will lead to pressure equalizing between the two. Since we are not talking about a storage container that is many times larger than the propane cylinder, and the cylinder is filled with liquid that expands into gas until it creates enough pressure in the container to cause the transition phase to stop.

This all makes me think that a sealed storage container is a very bad thing. Consider the worst case, a tank leaks propane into the storage container to the point where some of it converts to liquid in the bottom of the container. As soon someone opens the container, that is going to flash off. Even if the container is held vertically as liquid propane flashes it will expand and push itself out of the container. If you are standing on the swim platform, maybe things aren't so bad. If on the other hand you standing in the cockpit, loose propane is going drop to the lowest point it can find, e.g. cabin , engine compartment etc.

Makes me think that maybe the thing to do is make a small container that is vented over the side like the commercial propane lockers.

Henry

 

[matthewmiller01]

I don't think you can use the ideal gas laws, or rather apply it in a formula that doesn't involve calculus because you're not dealing with a constant gas volume. As the pressure changes (drops) more gas volume is created as more propane molecules transition from liquid to gas.

A leak in the cylinder will lead to pressure equalizing between the two. Since we are not talking about a storage container that is many times larger than the propane cylinder, and the cylinder is filled with liquid that expands into gas until it creates enough pressure in the container to cause the transition phase to stop.

This all makes me think that a sealed storage container is a very bad thing. Consider the worst case, a tank leaks propane into the storage container to the point where some of it converts to liquid in the bottom of the container. As soon someone opens the container, that is going to flash off. Even if the container is held vertically as liquid propane flashes it will expand and push itself out of the container. If you are standing on the swim platform, maybe things aren't so bad. If on the other hand you standing in the cockpit, loose propane is going drop to the lowest point it can find, e.g. cabin , engine compartment etc.

Makes me think that maybe the thing to do is make a small container that is vented over the side like the commercial propane lockers.

Henry

...and you said your chemistry/physics wasn't as good as it used to be. :thumbsup:

All in all. I agree with you. I think the container vented over the side should be the only way to go. For me, I am thinking about a PVC storage tube (as has been previously discussed) that is sealed with a flexible vent tube out of it. I could store it in the wet bar trash locker and run the vent tube through the back wall of the wet bar trash locker to the engine compartment vent/blower discharge/cutout areas on the side of the boat. The vent tube would remain out of sight (unless you are in the water looking up into the vents) and would still be in the open air, outside the cockpit area. The vent tube would only need to be positioned to ensure that, should it vent off propane, the vapors would be "falling down" outside the boat vice into the engine compartment. All it would take (as far as modifications to the boat) would be a small drill hole for the vent tube and this hole would be in an inconspicuous location, far above the waterline. Of course, this is still only when storing the cylinders on board while we are out. They stay in the dock box (which is vented) when we are not planning on grilling. :huh: